How to Make Compost in 18 Days Using the Berkeley Hot Composting Method

Berkeley 18 day hot compost

Regular composting, also known as cold composting, involves placing a variety of organic materials in a compost bin, enclosure, or even just in a large heap, and leaving it there until it breaks down several months later. It’s a very slow process and typically takes 6 to 12 months. It can be sped up by turning the compost, that is, moving around the material at the bottom of the heap to the top and vice versa to mix it up and get more oxygen in there, but it’s still a long wait. But there’s a better way to do composting…

The Difference Between Hot and Cold Composting

The other approach to composting is hot composting, which produces compost in a much shorter time. It will effectively destroy disease pathogens (such as powdery mildew on pumpkin leaves), weed seeds, weed roots (such as couch and kikuyu) and weeds which reproduce through root bulbs (such as oxalis). This process breaks down the material much better to produce a very fine compost.

By comparison, the slower cold composting methods will NOT kill disease pathogens or weed seeds and roots, so if this compost is put into the garden it may spread weeds and plant diseases, hence the common advice not to (cold) compost diseased plants.

The other issue with cold composting is that it produces a coarser compost, with lots of large pieces of the original materials left over in the compost when the process is completed, whereas hot compost looks like fine black humus (soil), and none of the original materials are distinguishable.

Hot composting is a fast aerobic process (uses oxygen), so given volume of compost materials produce almost the same volume of finished compost. In contrast, cold composting is slow anaerobic process (without oxygen), it’s a different chemical process, and as a result, nitrogen and carbon are lost to the atmosphere, which causes a reduction in the volume of compost to 20% of the original volume.

hot cold composting

The Berkeley Hot Composting Method

The hot composting method, known as the Berkeley method, developed by the University of California, Berkley, is a fast, efficient, high-temperature, composting technique which will produce high quality compost in only 18 days.

The requirements for hot composting using the Berkley method are as follows:

  1. Compost temperature is maintained between 55-65 °C (131-149 °F)
  2. The C:N (carbon:nitrogen) balance in the composting materials is approximately 25-30:1
  3. The compost heap needs to be 1m x 1m (3′ x 3′) wide and roughly 1.5m (5′) high
  4. If composting material is high in carbon, such as tree branches, they need to be broken up, with a mulcher for example
  5. Compost is turned from outside to inside and vice versa to mix it thoroughly

With the 18-day Berkley method, the procedure is quite straightforward and can be summarised into three basic steps:

  1. Build compost heap
  2. 4days – no turning
  3. Then turn every 2nd day for 14 days

Detailed, step -by-step instructions of the Berkeley hot composting method are provided later in this article, but before we can begin composting , we need to get the right mix of materials into our compost!

Getting the Best Composting Material Carbon-Nitrogen Balance

In all composting, including the Berkeley hot composting method, the ratio of carbon to nitrogen in the compost materials needs to be between 25 to 30 parts carbon to one-part nitrogen by weight. This is because the bacteria responsible for the composting process require these two elements in those proportions to use as nutrients to construct their bodies as they grow, reproduce and multiply.

Materials that are high in carbon are typically dry, “brown” materials, such as sawdust, cardboard, dried leaves, straw, branches and other woody or fibrous materials that rot down very slowly.

dried plant matter

Materials that are high in nitrogen are typically moist, “green” materials, such as lawn/grass clippings, fruit and vegetable scraps, animal manure and green leafy materials that rot down very quickly.

lawn clippings 02 Background of Mixed Vegetable Leftovers

Many composting ingredients don’t have the ideal carbon to nitrogen ratio of 25-30:1. To make composting work, we get around this problem by mixing high carbon materials which break down very slowly, with high nitrogen materials which decompose very quickly, in order to create the right balance.

The nitrogen content of composting materials is denoted by the carbon to nitrogen ratio (C:N ratio) assigned to them, as detailed in the tables in the next section. Before we examine those, let’s have look some quick examples to understand how C:N ratios work..

  • Materials high in nitrogen, which decompose very quickly, such as fish, which have a C:N ratio of 7:1, have a very low C:N ratio .
  • Materials low in nitrogen, which break down very slowly, and need to be broken up to be used, such as tree branches, which have a C:N ratio of of 500:1, have a very high C:N ratio

The rationale for mixing ingredients is as follows.

If the C:N ratio in our composting materials is too high, meaning we don’t have enough nitrogen and too much carbon, we can lower the C:N ratio by adding manure or grass clippings, which are high in nitrogen.

If the C:N ratio in our composting materials is too low, meaning we have too much nitrogen, we you can raise the C:N ratio by adding cardboard, dry leaves, sawdust or wood chips, which are high in carbon.

When trying to understand C:N ratios, it may helpful to point out that all plants have more carbon than nitrogen in them (remember, they get their carbon from the carbon dioxide in the air) so that’s why the C:N ratios of plant material is always greater than 20:1.

Below are the average C:N ratios for some common organic materials used for composting

Carbon-Nitrogen (C:N) Ratios of Common Composting Materials

Here is a handy list of composting materials with their respective carbon to nitrogen, or C:N ratios.

The materials at the top of the list contain higher amounts of carbon, but are low in nitrogen, and are considered ‘browns‘.

As we move down the list, the nitrogen content increases, and the materials at the bottom of the list contain higher amounts of nitrogen, and are considered ‘greens‘.

Browns = High Carbon C:N
Wood chips 400:1
Cardboard, shredded 350:1
Sawdust 325:1
Newspaper, shredded 175:1
Pine needles 80:1
Corn stalks 75:1
Straw 75:1
Leaves 60:1
Fruit waste 35:1
Peanut shells 35:1
Ashes, wood 25:1
Greens = High Nitrogen C:N
Garden waste 30:1
Weeds 30:1
Green Wood 25:1
Hay 25:1
Vegetable scraps 25:1
Clover 23:1
Coffee grounds 20:1
Food waste 20:1
Grass clippings 20:1
Seaweed 19:1
Horse Manure 18:1
Cow Manure 16:1
Alfalfa 12:1
Chicken Manure 12:1
Pigeon Manure 10:1
Fish 7:1
Urine 1:1

What Materials Can Be Composted?

Anything that was once living can be hot composted – and I really do mean anything. All manner of things, including unusual items such as wool and cotton clothing, bones, leather boots (with leather soles).

Some farmers who use the hot compost method even place a fresh animal roadkill into their hot compost heaps (they have to go in the very centre of the hot compost heap to break down properly) because they are a high nitrogen source, and they find nothing but clean bones when the compost is ready. Not a good idea for urban areas though!

It’s best to use a variety of different ingredients in the compost, as this provides an input of a wider range of nutrients, and produces a richer compost.

There are many organic materials that can be composted, and there are also certain ingredients that should never be put into a compost bin. This is subject is a whole article in itself, so if you want more information, here is a link to a list of what materials should and shouldn’t go into your compost bin.

The Easiest Way to Mix Compost Materials for the Right C:N Ratio

Some gardeners are perfectionists and try to use some very complex mathematics to calculate the exact proportions of each ingredient they’re using to arrive at the ideal C:N ration of 25-30:1 by weight. This is totally unnecessary, and there’s a very simple alternative that works great, which is a measure by volume.

The One Bucket Greens, Two Buckets Browns Method

If ratios seem too complicated or confusing (which they are), you can work with volumes of ingredients instead to simplify things.

  • Use 1/3 ‘greens’ (nitrogen containing) materials with 2/3 ‘browns’ (dry carbon materials).

Or to put it another way, which may be easier to understand:

  • Add one bucket of nitrogen-rich material to every two buckets of dry carbon-containing material.

For example, using this method we could use 1/3 Manure and 2/3 dry carbon materials to start a hot compost pile and it will work. Alternating thin layers of greens and browns are laid down until the compost heap is 1 metre (3 foot) square and a bit taller than that.

There’s no real need to get caught up in the mathematics of precise C:N ratios for succesful hot composting. It’s more a matter of trying out the process by following the instructions below, and it really is quite easy.

Hot Composting in 18 Days, Step By Step Instructions

The following instruction detail the steps required to build a Berkeley hot composting system which will produce finished compost in around 18 days.

DAY 1 – Construct Compost Pile, Let it Sit for 4 days

  1. Mix together ingredients by laying then in alternating thin layers of “greens” and “browns”.
  2. Wet the compost heap down very well so it is dripping water out of the bottom and is saturated.
  3. Let the compost pile sit for 4 days (this day and three more days), don’t turn it.
  • Tip: A compost activator such as comfrey, nettle or yarrow plants, animal or fish material, urine, or old compost, can be placed in the middle of compost heap to start off composting process.


DAY 5 – Turn Compost Pile, Let it Sit for a Day

  1. Turn the compost heap over, turning the outside to the inside, and the inside to the outside. To explain how to do this, when turning the compost, move the outside of the pile to a spot next to it, and keep moving material from the outside to the new pile. When the turning is completed, all the material that was inside the pile will be outside and vice versa.
  2. Ensure that moisture stays constant. To test, put gloves on and squeeze a handful of the compost materials, which should only release one drop of water, or almost drips a drop.
  3. On the next day, let the compost pile sit, don’t turn it.
  • TIP: If the compost pile gets too wet, spread it down, or open a hole about 7-10cm (3-4”) wide with the handle of the pitchfork, or put sticks underneath for drainage.


DAY 7 & DAY 9 – Measure Temperature, Turn Compost, Let it Sit for a Day

  1. Measure the temperature at the core of the compost heap.The compost heap should reach its maximum temperature on these days. As an simple guideline, if a person can put their arm into the compost up to the elbow, then it is not at 50 degrees Celsius, and is not hot enough. Best to use a compost thermometer or a cake thermometer for this purpose.The hot composting process needs to reach an optimum temperature of 55-65 °C (131-149 °F).At temperatures over 65 °C (149 °F), a white “mould” spreads through the compost, which is actually some kind of anaerobic thermophilic composting bacteria, often incorrectly referred to as ‘fire blight’. This bacteria appears when the compost gets too hot, over 65 °C and short of oxygen, and it disappears when the temperature drops and aerobic composting bacteria take over once again.Temperature peaks at 6-8 days and gradually cools down by day 18.
  2. Turn the compost heap over every second day (on day 7 and again on day 9).
  3. Allow the compost to rest for on the next day after turning it.
  • TIP: If the compost pile starts coming down in size quickly, there is too much nitrogen in the compost.
  • TIP: To heat up the compost faster, a handful of blood & bone fertiliser per pitchfork when turning speeds it up.
  • TIP: If it gets too hot and smelly and goes down in size, it has too much nitrogen, need to slow it down, throw in a handful of sawdust per pitchfork when turning.




DAY 11, 13, 15 and 17 – Turn Compost, Let it Sit for a Day

  1. Continue to turn the compost every 2nd day (on days 11, 13, 15 and again on day 17).
  2. Allow the compost to rest for a day after turning it.

DAY 18 – Compost Completed, Ready to Harvest

  1. Harvest completed compost, which will be warm, dark brown, and smell good.
  2. Congratulate yourself for a job well done!
  • TIP: When the earthworms move into the compost, it’s a sign that it’s finished and ready, because it’s cooled down enough for them and they’re in there because it’s full of nutrients!


Some important points to note:

  • Locate the compost heap in an area which is protected from too much sun to prevent the compost from drying out, or from heavy rain to avoid water-logging, as both extreme conditions will slow down the composting process.
  • Space required for for your heap should be about 1.5 x 1.5 metres (5′ x 5′), and enough space in front of it to stand when turning the compost.
  • Water each layer until it is moist as you build the heap. After three or four days, give the compost air by mixing and turning it over, then turn every two days until the compost is ready, usually in 14-21 days. Remember, frequent turning and aeration is the secret of successful composting.
  • Turn the compost using a garden fork, or even better, a long-handled pitchfork.
  • In cold or wet weather, cover the compost heap with a tarp or plastic sheet, to prevent the rain cooling it down, since the water will penetrate into the core of the compost pile. Even though cold outside air will cool the surface, but not the core of the compost heap, by covering it, this prevents some heat loss from the surface to cooler outside air, and retains the heat within the compost heap better.

Is My Garden Too Small for Hot Composting?

A full–sized hot compost pile can be made successfully in a small courtyard, I know from experience!

The first time I tried hot composting was assisting a friend with only a small courtyard in a rental property, who had never tried this process before. For composting materials, he gathered a wheelie bin full of fallen leaves from his local street, a second wheelie bin full of weeds from his garden, and he also purchased a small straw bale for the sake of it. I also helped him collect a few garbage bags of cow manure from an urban farm. It took us under an hour to pile up all the materials in reasonably thin layers of less than 5cm (2″) to build the compost heap.

Even though it was his first attempt at hot composting, and in around 18 days, he had over 1 cubic metre of rich, dark, compost to use in his garden. None of the original ingredients could be identified in the final product either, it had a very fine consistency. Best of all, it cost him next to nothing – the straw bale was the only item purchased, and that was more of a gratuitous addition, as the hot compost would have worked just as well without it.

Considering that a hot compost pile doesn’t really reduce in volume, the biggest issue in small yards and gardens is figuring out what to do with such a large volume of high-quality compost!

Ways to Use Compost in the Garden

Wondering what to do with over a cubic metre of freshly made compost?

  • It can be used to improve your soil by digging it through your garden beds.
  • Don’t like digging? Use the compost to start a no-dig garden with the no-dig gardening method, which is my personal preference!
  • Compost should be always mixed into the soil to improve drainage in heavy clay soils, and to improve water retention in sandy soils when planting new trees.

These are just a few ideas to get things started. Happy composting!

711 thoughts on “How to Make Compost in 18 Days Using the Berkeley Hot Composting Method

  1. Beautifully & clearly explained . Thank you. Methinks you ought to be a teacher.
    Of anything at all ! I suspect you love the process ? Especially PERMACULTURE .
    [ I visited your back yard once with the NERP PERMIE mob. Most impressive, as we all said on the day. I have meant to say previously : YOUR concern about the lead sheet flashing around the chimney is misplaced – with all due respect. I guarantee that you could not detect a DIFFERENCE between water from the East face of the house and the west face. Consequently I suggest that NOT collecting all that water ‘cos of the lead sheet flashing is a waste. { I also heard that there was a second reason for NOT collecting same ! } ] Warm regards david hicks…..Eltham N.

  2. Thanks David,

    Appreciate the supportive feedback. You’ve got it right, I do have a passion for training/teaching, trying to do a career change into this area! Would love to teach permaculture!

    Thanks for the advice on the lead flashing, it’s quite common on a lot of old buildings as you know, and it is a concern for quite a few people. I seriously haven’t looked to deeply into the matter, namely because my tanks can only hold the water I capture from the garage roof (30 sq. m), don’t have capacity for the rest, that would come at a later date. There are a few other minor technicalities too, which I won’t burden you with.

    I’m currently working on a food garden community project, and they’re also avoiding capturing water off a slate tile roof with lead flashing. There’s so much water there to be had…

    I agree, it is a terrible waste not to capture the water. I would love to be able to do the testing or find some research on the matter, because it’s very common for people to err on the side of caution, and not capture water in these situations.

    You’ve motivated me to go do some research and find some scientific research papers on this, because if you’re right on this, and I don’t have reason to doubt what you say, this will give immense reassurance to people in this situation, and increase the amount of water captured for productive use, rather than flow down the stormwater drain.

    You’ll most likely see an article on this soon if my seearch goes well, thanks for inspiring me to look into this!


    1. Urine, coffee CHAFF, water, witch’s hat composter, Boston, MA–winter

      Hi, I’m wondering if anyone on this list could help me with the ratios, etc. for this project? Would I be better off sealing it into a barrel with holes and rolling the barrel around, like those big composting spheres? The idea behind the witch’s hat composter is that the inner hole filled hat aerates the pile, the top hat covers it and exerts some downward pressure (it’s surrounded by a 4 ft tall perimeter of plastic). Thanks.

      1. What I understand of this process is that it needs to have a minimum volume to attain the ideal temperature. That seems to be close to 1 cubic meter, a little more than a cubic yard or 30 cubic feet. If smaller the core would not attain the temperature of 55-65’C 130-150’F. Multiply this by ten and you have enough heat for your house for a season. The article says 1.5m (5ft) high pile, which as a pyramid comes to about 1 cu.m If your pile becomes too big with the right composition you have to monitor the heat at the core and turn it if it exceeds the high temperature limit. It does work if you can get a huge barrel. You may have a hard time rolling it as it probably weighs about a ton and a half (barrel and contents). That’s as much weight as an old Lincoln 🙂

        This whole method I believe was devised by Jean Pain in France who unfortunately died too young, but wrote a book about it. It is called the Jean Pain compost method, not the Berkeley method. Pain’s goal was not to produce good compost but to extract heat and energy out of the composting process. He heated water pipes and collected methane.
        Here is a link and the book itself that has been out of print

        Geoff Lawton mentions this in his movie “Soils” and he is one of the forefathers of permaculture and my favorite advocate. The reason he is my favorite is that he presents the subject in a way that emphasizes that this can not possibly be perceived as “individual practice and solution”, but a collective-communal paradigm shift for humanity to become what it really is, on point in this huge cycle of life and coexistence – sustainability. “It is the only hope we have”, he says, as a specie.

      2. For making compost, and lots of it, it’s the Berkley method! 🙂
        The volume given of one cubic metre is a minimum, there is no maximum size, some farmers turn piles that are much higher and many metres long with a front-end loader. The 1.5m pile is not really a pyramid, more a rectangular mound with a wider base, which is over 1 cubic metre in volume.

        Yes, Geoff Lawton (my teacher along with Bill Mollison) explains technical material brilliantly and he explains it in terms of systems that work together. No man is an island, we all achieve more when we work together as a community.

    2. I also workfort a community food garden (it supplies a food pantry for the needy) and also helped with the redesign of another community garden that is about 1/4 acre. That second garden had an IBC water tank but it was attached to nothing… and a shed in another area. With the redesign they are now getting all the water they need by collecting water from both sides of the shed. My point is, even small sheds can collect quite a bit of water. If your building won’t work, could you get a small (10′ x 12′) shed and collect water from it instead of the building with lead flashing?

      1. Dry bamboo, fresh bamboo? It depends. Dry bamboo would have the same C:N ratio as wood chips, and fresh bamboo would have the same C:N ratio as garden waste, because they’re essentially the same materials.

      2. I would use both. I was curious because Bamboo is considered in the same family as grass so it’s interesting. I have a lot of both dry and fresh.

    3. Hi. I enjoyed reading your website, it’s very well put together. Just one thing I would say is not correct in my experience as organic gardener and educator. A cold heap is not necessarily, or at least shouldn’t be, anaerobic. It still needs aeration and with the right balance of carbon and nitrogen and regular turning it would prevent this from happening. An anaerobic cold heap would smell, probably isn’t looked after and possibly contains too much nitrogen rich materials like grass clippings. It attracts the kind of bacteria you don’t want in the garden and is not considered to be a good approach..

      1. Thanks for the great feedback! Perhaps I should express myself point better when discussing cold composting. Cold composting only turns anaerobic when it goes terribly wrong! Both hot and cold composting are aerobic processes, the former is just a lot faster than the latter. When both types of compost are are turned regularly, they become aerated, which promotes breakdown of the materials, and production of compost.

  3. Hi Angelo,

    I’m loving your website, thanks mate.

    This thread spurred me to research. Lead in tankwater is a real consideration, this from a CSIRO study: “The rainwater collected from all three roofs with lead flashing contained Pb concentrations exceeding the ADWG (and WHO) maximum recommended values”

    I’ve had it recommended by someone to put lime and/or shells into the tank so the water turns alkaline and lead precipitates out of solution. This paper looks like it’s saying that’s not an effective strategy…

    Quote: “an increase in carbonate promotes formation of more soluble lead carbonate complexes.”

    There are effective water filters for drinking. Not much use for the garden.

    Can you really make a compost without it shrinking? I’ve never done that. I think they produce a lot of carbon dioxide as the microbes metabolise, so you have to lose some mass. And the whole thing settles too so loses some extra volume. That’s my experience anyway.

    I’d love to teach a permaculture course with you someday!


    1. Hi Adam,

      Thanks, really appreciate the links to the lead in tankwater research, I was looking for this information as it’s a topic of concern for many people who wish to harvest rainwater from their rooftops, lead flashings unfortunately are quite commonly used on Australian rooftops.

      With hot (aerobic) composting, you’re right, the process of aerobic decomposition will oxidise carbon and create cabon dioxide, the amount of carbon is reduced as all the available nitrogen is utilised and captured. The reduction will be ever so small if you have an abundance of carbon rich materials so nitrogen is not lost. If the compost heap is compacting down too much, you need to add more carbon-rich materials. Agreed, the volume will also reduce slightly due to the physical breakdown and subsequent compaction of the composting materials too. You’ll lose some volume, but nothing drastic, my guess is you’ll definitely always have well over 50% of original volume, possibly closer to 75%. It’s hard to estimate accurately because I’ve never measured the volume accurately, so my estimates are somewhat subjective. Compare this with slow anaerobic composting, where the you will only end up with 20% of the original volume, you lose around 80% of volume, that’s quite a difference! It’s quite disappointing with slow (anaerobic) composting to fill a 200L compost bin and end up with only 40L of compost, but it’s still something…

      Love your work too, would most welcome the opportunity to teach a permaculture course together!


    2. Adam, it’s pretty easy to design a water collection system to have a “first flush” feature to it. The first rain that comes would take the majority of the pollutants (like lead from the flashing) with it, and then the remainder would be much cleaner, and can be sent through a filtering system to remove what remains. This really isn’t as hard as it sounds. There are a number of options for designs so I won’t go into detail, but usually I come across designs on YouTube or at off-grid living websites (where they are needing to use the rainwater for drinking water).

  4. Hi, awesome site. Can you explain how to keep the temperature of the compost at 55-60 Celsius? I’m guessing you put it under a heat lamp?

    1. Hi Jason, thanks for your comment. There is no need for an external heat source at all, the bacteria in the compost heap generate the heat by themselves! They can generate so much heat that haystacks on farms which have gotten damp in the centre and have started composting can actually burst into flames! Luckily that won’t happen with the compost. The bacteria consume the compost heap as they multiply, and when they chemically break down the organic matter into simpler compounds, heat is released. This encourages the heat loving bacteria, which break down the compost even further. That’s the magic of hot composting!

      1. I have often wondered how the bacteria release heat, and i’m guessing it is by breaking chemical bonds with their digestive process, but i know nothing more. Do you know anything more about this? Does it have to do with nitrogen being turned into nitrates?

      2. Jason, I use a long probe thermometer inserted into the center of the pile. When it reaches 150 I turn the pile. I use shredded leaves and chopped alfalfa. A lawnmower works just fine for this.

  5. Hi there. Great instructions! The only thing is, I’m based on the West Coast of Ireland. Its summer now and the weather is blustery and cool with sporadic sunshine. Will this quick composting system still work here or does the outside air temp affect how the bacteria generate heat? ie: will this weather slow down the process? I am a permaculture student and everyone who has passed on their knowledge of hot composting systems here in Ireland say it will be ready at the earliest 6-8 weeks after constructing. Do you have any thoughts or tips on this?
    Thank you! Julie

    1. Hi Julie,

      I didn’t realise Irish summers are so cool (cold)!

      The hot composting process is driven by the bacteria, they generate the heat through the decomposition of the organic matter in the compost heap.
      The compost heap is normally covered with a tarp or plastic sheet, to prevent the rain cooling it down, since the water penetrates into the core of the compost pile.
      Cold outside air will cool the surface, but not the core of the compost heap. The covering prevents some heat loss from the surface to cooler outside air, and retain the heat within the compost heap better.

      I must confess, I can produce compost in my tumble bin in 6-8 weeks in winter here. It only holds 200 litres, not enough for the hot composting process, and it only gets warm.
      I’m pretty sure a hot composting pile should still work in 18 days in even a cool summer.

      Ok, here’s a few tips to keep that hot compost pile running hot in cooler weather:

      1. Make the pile as big as you can, bigger compost heaps retain heat better than smaller ones.

      2. Increase the amount of nitrogen sources (greens) in the compost

      3. Add some very ‘hot’ sources of nitrogen, such as horse manure, chicken manure or coffee grounds

      4. Insulate the compost heap to retain the heat – cover it with a black plastic tarp (not airtight though, it needs a good supply of oxygen) or any other insulating material, get creative!

      5. Place your compost in a location where it is protected from the wind.

      6. Situate the compost heap in a position where it receives full sunlight (north in the southern hemisphere, south in the northern hemisphere)

      Im curious to know how well it works in a cold Irish summer!


      1. How do you manage to get cold/cool compost finished in 6 weeks?
        I’ve been tumblimg mine for 2 months and isn’t even halfway there.
        Do you use a similar C/N ratio as per hot composting and have you any tips for those of us who struggle to find space even for a 200l tumber and have no chance of building a big hot compost pile.
        Very nicely written article btw
        Gerry C

      2. Thanks Gerry, the trick to getting cold composting in 6 weeks is as follows:
        1. Processing – Feed all materials through a mulcher first, the finer the compost materials are, the faster they break down. I think this makes a huge difference. Otherwise, just chop materials quite fine with a garden spade on the ground (not in the soil, it will compact it!), or using secateurs or hedge clippers to chop everything up first while the materials are sitting in a large container.
        2. Temperature – composting slows down in the cold weather, placing the compost tumbler in a warm spot speeds things up, and the 6 week turnover only happens during the warmer seasons for that reason.
        3. Materials – use materials that break down relatively quickly, and use a good mix of materials. For carbon containing materials, pea sraw, lucerne, dried grasses, newspaper break down faster than heavy branches that are mulched and still consist of large, chunky pieces. Add lots of nitrogenous (green) material, this breaks down very fast. Ratios of carbon to nitrogen are the least critical in a compost tumbler, technically you could compost green grass clippings alone as long as you turn it daily, but it’s best to add a good mix of mterials to try to achieve the optimum C:N ratio. With too much excess nitrogen, you lose to much of the nitrogen from the compost to the air because there is not enough carbon to bind it.
        4. Volume – try to get as much materials as possible to fill the compost tumber in one go, it will heat up a bit on its own, but not enough to make it a hot compost, so it’s still cold composting.

  6. Ah, thanks a million for your speedy response – much appreciated. Will definitely use onsite horse manure to help heat pile. We also have sheep manure mixed with straw that I am hoping to use. Just wondering what your thoughts are on using bracken as a green? We have an abundance of. Some people seem to think that it doesn’t break down properly. I was also thinking of using it for capping the heap as an insulator under the black plastic.
    Also I have often been told that having a particle size of 2.5cm3 is optimum – is this neccessary for such a quick system?
    Will keep you updated as to the results of our test!
    Thanks again, Julie

    1. Hi Julie,

      No, there’s no real need to break up the material into very small pieces when hot composting, the combination of heat and bacterial activity can break doen a lot of things that would surprise a lot of people. – materials added to the centre of hot compost piles that have broken down completely include such things as leather boots, woolen jumpers, and roadkill (dead animals). With the latter only clean bones are left behind. Breaking things up roughly is usually sufficeint. 2.5cm3 or one cubic inch is the particle size you get from a chipper (a coarse mulcher), which is what I use for cold composting. Chopping up the material finely increases the exposed areas in the material that bacteria can act on, naturally speeding up the process of breakdown and decomposition. It definitely always helps but is not critical in hot composting.

      Also, bracken ferns can be hot composted. Normally they are allelopathic, that is, they release chemicals which prevent other plants from growing, but thankfully the hot composting destroys these substances. Bracken ferns are a good source of potassium and break down slowly to create an acidic compost.

      The Royal Horticiltural Society mentions using Bracken Ferns as a compost, see

      Here’s a brief extract from the RHS article:

      Using bracken for composting or as a soil improver The young green fronds of bracken can be collected for the compost heap where they will rot down slowly, enriching the nutrient content of the compost. Bracken stems are too woody to be added to the compost or leafmould heap, unless they are first shredded or chopped into small sections.

      Bracken produces numerous spores, but these seldom seem to germinate and grow in the compost heap. Small sections of the roots can regenerate, and therefore should not be used in the compost.

      Dead bracken collected in autumn can be rotted down to make mulch, in the same way as tree leaves are collected and rotted down to make leafmould.

      Bracken ferns are believed to be carcinogenic, the current opinion is that people working extensively with them are at an slightly increased risk so try not to breathe the spores when working with them, a face mask might be a good idea.


      1. Ah great! Thanks for that!

        So we are on day 11 of our hot composting in a cold climate experiment. We turned it again yesterday and it is still quite hot – 55-60 degrees in places. On the first few turns there was evidence of slight white mould but only on bracken in the heap. We added shredded newspaper to counteract.
        So yesterday, on day 10 turning, we became a little concerned at how all this material will breakdown into lovely ready to use humus. Though the heap is hot and obviously some breakdown is happening, most of the the ingredients can be identified as their orignial state ie: straw, comfrey, hay, bracken etc.
        I am wondering if we are on track or what condition the materials should be in on day 10?
        I have taken photographs if you would like to have a look at how its doing.
        Thanks again for all the advice and support.

      2. Hi Julie,

        If the temperature is in the 55-65 degrees celcius range, it’s on track, it should be OK. You’re only half way there right now, the breakdown of the material speeds up as the bacteria multiply exponentially, and there is a lot more of them to consume the compost materials!

        Remember, around day 8 is when the temperature peaks, the next 10 days is the ‘slow bake’ period that will literally cook all the ingredients and break them down so they won’t be recognisable. The heap will be hottest in the centre, and the outside will naturally be cooler, which is why you turn it, so the outside material is put into the hot centre to break down. As mentioned in the article, if it starts to cool down, you can heat up the compost by adding a handful of blood & bone fertiliser per pitchfork when turning.

        Please let me know how it goes after the 18 days, as I’m sure many people are curious how the process works in cold contitions.


  7. What an interestingly well written site. I seem to fall into the notorious 10% of people who still have things to learn and add to my 50 yrs. of trial / error frugal gardening..

    Born and bred in the N. Texas sparsely wooded black-land native grassy prairies, between ‘temperate zones” ranging from well below 0 degrees F to 114 degrees F, I chose to Zeriscape about twenty years ago, having learned from a N. American university -who’d successfully beaten the dreaded weeding/ watering drudgery with the right formula utilizing local available free materials and recylables.

    [I’ve nearly died with every sort of compost formula’s molds,
    fungus, and failed results, heavy labor, suggested DIY contraptions, and guesses, learning that few are designed for this zone/ temp
    fluctuation and unpredictability/ toxicity we have here in city water, air pollution, [GMO/ hybirdizing of seeds], chlorine-gassing of most retail-sold vegetables and fruits, ignorance of “recommended pesticide useage’ by so-called ‘local experts’, laws growing agianst local organic farming, wrong and/or omitted important information resulting in greatly compromised immune systems of my large urban corner home and yard, as well as my slightly oversized but weakened, aging body! It’s enough to make an old gardener to give

    Have I? Nope. Like Thomas Edison, I have learned from hundreds of things and ways that don’t work ! It’s been a full circle of back-to-
    basics/ Garden of Eden– thinking, greater common sense -regardless of ‘latest ideas’, and I now have a wonderful organic biosphere with VERY few, if any, pests or diseases, and several crops that have both grown and encouraged me to use all I have observed, re-thought, analysized, and concluded…to my full advantage, thanks to the Grace of God !!

    The frequent feeding of the birds, squirrels, and observation of the advantages to having them,I more fully appreciate my variety of lizards and non-agressive ants, as God helps to balance it all. I’m having good success with top of ground, non-turning, cold composting, with the local vermi-culture/ beetles/ a few wasps/ and refuse from my wonderful, fat 3yr. old house-hen, 4 yr. old house rabbit [both contained in large waist high cages-cleaned-daily], along with a treasure-find of an electric ionizer/air freshener which totally eliminates any odors in ten minutes!

    With weather extremes, black clay soil, frequent lawn-watering restrictions because of weather extremes?, and many trees/ shrubs, I’m trying to find ways to work within my boundaries, to preserve my VASTLY diverse landscape and strange EDIBLE native-plant takeover of my back yard. [Just thought I’d drop by and share from a reader of another region’s dilemma and to say,”. Keep up the good work; don’t give up, even on the white/black/green/red/ orange funguses !! or on learning. It’s both a challenge and a TRIP.


    1. Updating, moved temporarily to the near countryside. Discovered that, in old home needing repairs, that my entire garden and flower beds were literally crouded with the largest most incredible GRUBS, not the usual ones, but gi-normous ones. Learned that my compost was so rich, plentiful, well decomposed that it was THEM who turned it into what I hoped it would be, but cannot use after all?

      Downside: They continued eating the roots on everything smaller than a tree root!! Called the most reliable organic growers/retailers whose best horticulturist gave me the bad news: NOTHING so far is able to phase these creatures because they are particularly LARGE
      and from ASIAN beetles [metallic variations on backside] that do NOT respond to Milky Spore. Since I’m all organic, I am searching frantically to find a natural deterrent or host to keep them at bay.

      Any ideas or ‘latest news’ re these HUGE, nearly [small] chicken-leg sized grubs would be deeply appreciated. My yard is almost DIRT now and the most discouraging info says there is NOTHING I can do short of eliminating the dream of lawn/ bedding repair, and to plan
      for ‘hardscaping’ instead.

      So, unless some reader with additional info has a better idea, I’m going to pursue shadecloth under gravel meandering paths, repositioning my tub garden and bird baths, and streamline using what I already have but expanding into the lawn. According to the advice, I may even have to resort to artificial plants!!

      Of course this situation may change if the coming extraordinary heat predicted for Texas is a reality, which just MIGHT penetrate deep enough to COOK whatever larva which may be lingering, getting hungry – having been so greedy as to eat both compost AND root system of the majority of my large corner lot!

      It’s like a bad SCI-Fi movie, but God is good and may answer my prayers of distress. Afterall, He knows all things, including just HOW these beetles and grubs became so large, as well as what to do about it! What a dilemma!

      1. The permies say… You don’t have a slug problem … You have a lack of ducks problem.

  8. Can you use sulfate of ammonia (N) in the place of greens? Will it aid in the brake down of the carbon material and heat the compost pile?

    1. Hi Harris,

      I would NOT use ammonium sulphate in my compost, it’s a strange practice that non-organic gardeners are recommending, and I think it is a very bad idea.

      Here are a few reasons to consider:

      Ammonium sulphate is acidic, you don’t want ti acidify your compost.

      It’s a mineral salt, so in quantities significant enough to contribute nitrogen, it will possibly be too high a salt concentration that will disrupt the bacteria and fungi in the compost pile ecosystem, and will probably slow the composting process down.

      Compost is not just carbon and nitrogen, these are just the major elements that bacteria use to consititute themselves from as they multiply, but you need lots of other elements and substances in there too for bacteria to grow and break down the organic matter, and for the resulting compost to be useful as a plant food, which is ultimately what we want the compost for. Green organic matter contains all the other substances that aid decomposition.

      Using a wide variety of ingredients creates the richest compost, which will be best for your garden. Using very few ingredients will make for a lower grade compost.

      You have to pay for ammonium sulphate, and other than being unsustainable, having to pay for a nitrogen fertilizer is crazy, considering that is what all living organisms excrete as bodily waste!

      I personally would discourage the practise, there are so many nitrogen sources freely available that the need to put chemical fetiliser in your compost would be hard to justify. It would really be easier to just urinate in the compost heap a few times if you needed to top up the nitrogen, seriously. You wouldn’t just use this as the only nitrogen source, since urine can have high sodium levels, we excrete salt this way, and you don’t want high salt levels in your garden either.

      Just look at the list of nitrogen sources I have listed, there are 17 of them there, and there’s lots more available I haven’t listed, I’m sure some of these must be available.

      Keep it all natural and organic, and you’ll be much happier, and so will your compost!


  9. Thank You. I’ve been looking for a better explanation on Hot Composting. I just like doing things in such a way that they require less work from me. I saw a special that featured African woman in this village that collected all the food waste in a special roofed area where they had three piles: new, once turned, twice turned. As it composted the piles were turned and a stick pushed into them. To check the temperature they pulled out the stick and touched it to make sure it was nice and warm. The finished material was put into their gardens.
    But, as we are running out of oil we should stop composting and look to get the most out of every calorie we can get. To replace composting collect all animal and human poop (pee too) as well as plant materials from the garden and kitchen. Slurry them (about like running oatmeal) and pour into a methane digester. What you get is methane and a high quality fertilizer. Two things where before you had one. More bang for every calorie.

  10. Hello,
    I was wonderin if you can collect your composting material over a period of time? I dont have that much material ready at once, but I throw all my kitchen scraps in the small bins I have for that in my backyard. Can I keep collecting the material and then start a big pile at once? Or can I use this method with small bins?
    Thanx in advance.

    1. Yes, you could gather your compost materials over time, and they will start cold composting where they are stored but that shouldn’t be too much of an issue, you will just lose some of the nitrogen content. Pile it all up when you have enough materials, then add some extra nitrogen materials (greens or manures) because nitrogen gets lost over time when storing the materials.

      You can’t hot compost with small bins because you need a minimum of one cubic metre of materials to get the hot composting process running.


      1. I have tried my first ever hot compost pile thanks to your excellent info. I wanted to share my experiences.

        I’m in inner city Melbourne Australia

        Because of lack of space I had to make a 1 metre square pen with chicken wire. I used veggie scraps, shredded green garden prunings, shredded dry leaves, lucerne hay, manure, molasses, partially broken down compost from my tumbler and smaller bin.

        I built up the pile to 1 metre square in 3 stages because I didn’t have enough materials in the beginning so I think the highest temperature I got to was 45 deg Celsius. I added some blood and bone at the second and third stage because I thought being built up in this less than ideal manner a nitrogen boost could help raise the temperature. Don’t know if this was a good idea or not.

        I lined the pen with hessian and then covered the top with hessian and a tarp. Because of the pen I couldn’t do your outside to inside turning method. My method was to shovel it all out and shovel it all back in again, mixing and breaking up clumps.

        I got some white powder at a few stages on materials in the pile like lucerne hay. This was towards the top of the pile so I didn’t think it could be due to excess heat. I was wondering if it was because I didn’t damp this layer down enough as I noticed it was dry.

        I used a mask over my mouth and nose when turning. But stopped using it towards the end when I didn’t think there would be airborne bacteria.

        It’s broken down quite nicely although of course it took a lot longer than 18 days because the bulk wasn’t there. It smelt good at all stages. I now have a lot of small, fine twiggy bits throughout and I was wondering if the best way to deal with this is to sift the compost so I can use the broken down compost and save the twigs for the next compost pile. I was thinking this might be the way to go because now that its lost its heat the twigs will take a long time to break down.

        I was interested in any thoughts on how to improve my process next time.

        And was particularly interested in the best way to build up a bulk of materials. I have a small garden so gathering materials takes a while.

        Am I best to shred everything as I get it and put it in my tumbler and small bin and then transfer it to the hot compost pen with new materials when I feel I have enough bulk.

        Or would it be better to just let the garden prunings sit without breaking them down and carry on with composting the veggie scraps in the tumbler with the appropriate balance of dry materials. And then when I have the bulk, mixing them all into the hot compost pen.

        I want my materials to be in the best shape they can be by the time I have the bulk to begin the hot compost.

        Any thoughts would be most appreciated and thank you for such a great resource.

      2. hi, if I need more carbon than nitrogen and storing depletes the nitrogen, then should I really have to add nitrogen back in, surely the ration of carbon to nitrogen will travel towards the correct ration for hot composting as nitrogen rich items are stored?
        I am interested in this specifically as I do not have enough carbon and am attempting to dry (through storage) some of the naturally nitrogen rich items to obtain carbon rich items, to store until I have enough material for a heap, i.e. I leave cabbage and other leaves, grass clippings, etc. out in the sun to dry then store them when they are crispy and brown looking to mix with freshly gathered of the same items. Is there a problem with my logic?

      3. I’m surprised that you can’t find enough carbon, it’s everywhere, newspapers, cardboard, fallen leaves and woody mulches are all very rich in carbon.

        Lawn clippings are already have the perfect C:N ratio, so it is very efficient to try dry them to lose nitrogen so you can use them as a carbon source.

        The flaw in the logic is that the materials such as kitchen scraps or lawn clippings have adequate carbon, what you’ve overlooked (and I failed to explain…) is that they’re primarily water! Think of how light fully dry grass clippings are, a bucket full will literally have no weight, so when you take out the water and the carbon content is quite insignificant. Most nitrogen-rich materials contain a lot of water, and therefore very little carbon as a percentage of their weight.

        Hope this helps!

  11. I was thinking of building a hot compost pile in my front yard before I build some large raised garden beds for veggie growing. There is space now but won’t be later. I was wondering if there is much smell. Would my neighbours find it a bit wiffy?

    1. Thankfully, there is no smell at all once its all built. The first hot compost pile I built in a friends small backyard, we used bags of very smelly fresh comw manure we collected from a farm, when the compost pile was built and watered, no smell whatsoever.

  12. I’m not sure I understand the 30:1 ratio. How is that achieved given the various ratios you show above. I mixed alternating layers of old compost, dried leaves, and manure to build my new pile. How can I tell if that will give the correct ration

    1. Hi Scott, you can use simple cross-calculation for the ratio.
      Assuming we’re only using straw (C:N ratio is 75) and chicken manure (C:N ratio is 12) for the compost (C:N ratio is 30), here’s how we can calculate it:

      Straw: (75) x 18 = 1350
      – =
      Target: (30) :
      – =
      Manure: (12) x 45 = 540
      2.5 : 1

      First we put the C:N numbers we know from our materials and the target in its places (x). Then we diagonally subtract the bigger number with the smaller. After that we multiply them horizontally, in the example straw’s C:N ratio is multiplied by the difference between target’s and manure’s C:N ratio. The two resulting numbers are the ratio for the ingredients. For this example we need around 2.5 part of straw for each 1 part of chicken manure. Based on the C:N ratio data, the ratio should be based on material’s weight, not volume.

      However, I just know how to deal with two ingredients using this method. Anyone knows how to calculate C.N ratio of multi-ingredients?

      1. ABSOLUTELY NOT NECESSARY ! (but read all to understand why and an “easier method to do”)

        Lets say C:N target = 30
        SUM = {30/C:N(1) + 30/C:N(2) + 30/C:N(3) + … + 30/C:N(n)} = let’s say “Y”
        If pile = 1,5m (=1.500 dm) (= ??? forks ? to determine, but don’t !)
        [{1500 x C:N(1)} / Y] = quantity C:N(1)
        [{1500 x C:N(2)} / Y] = quantity C:N(2)
        [{1500 x C:N(3)]} / y] = quantity C:N(3)

        [{1500 x C:N(n)]} / y] = quantity C:N(n)

        For example (if C:N target ? 30:1) and I have wood chips (400:1), garden waste, weeds (30:1) and cow manure (16:1), that give :
        30/400 + 30/30 + 30/16 = 0,075 + 1 + 1,875 = 2,95
        Parts :
        C:N(1) = 1.500 x 0,075 / 2,95 = 38 of the 1.500 parts or 2,53% (+/- 3%)
        C:N(2) = 1.500 x 1 / 2,95 = 508 parts of the 1.500 parts or 33,87% (+/- 1/3)
        C:N(3) = 1.500 x 1,875 / 2,95 = 953 parts of the 1.500 parts or 63,53% (+/- 2/3)


        Let’s try DIFFERENTLY since we know that an “approched” outcome is more than enough and, let’s work in “forks” (units) whatever the density of the avalable components (in composting, approximations are very broad : 1 “green” to 2″brown” is a glaring proof of that !)

        Returning to our previous results, we have “approximately” :
        1500 x 3% = 45 – 1.500 x 1/3 = 500 – 1.500 x 2/3 = 1.000
        wich gives, with a broader approximation, but considering “fork” units a proportion like this : 5 forks wood chips + 50 forks garden waste and weeds + 100 forks cow manure,

        Also, not that easy, BUT… observing this “expression”, it enables us to make extremely simple distribution calculations in practice : let’s replace the C:N in the table (once for ever) by “forks” (or units), based on the weeds or garden waste, (everybody has that!) .
        This will render the job very easier (the easiest way for me) :
        +/- 1 fork wood chips = +/- 10 forks weeds or garden waste
        +/- 2 forks cow manure = +/- 1 fork weeds or garden waste
        +/- 1 fork leaves = +/- 2 forks weeds
        – a.s.o. …

        So, if I have 10 forks of wooden chips, I mix them with 100 forks of weeds;
        if I also have 50 forks of cow manure, I mix them with 25 forks of weeds;
        and if I have 50 forks of leaves too, I mix them with 100 forks of weeds, a.s.o
        Then I mix all those little mixings together to have a rich compost.

      2. This is like my ‘buckets’ example, where it’s done by volume, but we add one bucket of nitrogen-rich (green) material to every two buckets of dry carbon-containing (brown) material.

        When the universities publish articles on making compost, they do a laboratory analysis of carbon, nitrogen and WATER.
        The water level is the critical factor, and many green materials contain a lot of water, and many dry materials contain a lot of air (where the water once was).

        The concern about using “10 forks of wooden chips, I mix them with 100 forks of weeds” is that instead of using 2 parts brown : one part green you’re using one part brown : 10 parts green which will most likely get too damp, soggy and anaerobic.

    2. Hi Scott, you can use this simple formula to guesstimate your compost ingredients.

      Ratio of ingredients =
      [CN1 x (CNtarget-CN2)] : [CN2 x (CNtarget-CN1)]

      In principle we multiply the C:N ratio of the 1st ingredient with the difference between 2nd’s and target, then compare it with the number we get from the opposite.

      For example if we’re using only straw (C:N=75) and chicken manure (C:N=12) to make compost (C:N target = 30), here’s how we calculate it:

      Ratio of straw : chicken manure
      = [75 x (30-12)] : [12 x (30-75)]
      = 1350 : 540
      = 2.5 : 1

      Please note as what we need is the differences, negative number is not a problem. Ratio of 2.5 : 1 means we would need approximately 2.5 kg of straw for each 1 kg of chicken manure. However I only know how to deal with 2 ingredients with this method, anyone knows how to calculate ratio with multi-ingredients?

    3. Angelo,
      Many thanks for your prompt answer.
      I must admit that I do “cold” compost. There is never a bad smell but my heaps reduce greatly, what attempt to give you reason. I also cannot control the carbon / nitrogen ratio at the end of maturation.
      Early, years ago, I used the ratio 2 brown/1 green. Results in reducing of the heaps were approximately same. You need a big quantity of “hard” brown matters to avoid that reducing heap.

      But… if my calculations are correct, the interpretation thereof is too. Otherwise…
      Assuming that I only have two available materials: wood chips (400:1) and weeds (30:1), HOW to get an average ratio of C:N ? 30:1 by mixing these two components? No calculation allows that!
      Only green materials at very very low carbon ratio can “reduce” the amount contributed by the wood chips. But in this case, it will still take a huge amount of these green materials relative to browns! If this is not the case, I don’t understand how the C:N ratios (given all over the Internet) may help and, above all, what’s the interest to know them since calculations give all in all fully inapropriate results?

      Many thanks then for comprehensive explanations of the “how to”, to get the “correct” calculated proportions in the mix with the easiest to find matters : weeds, wood, leaves, fruit + vegetable + garden waste, green wood and some animal manure (only curiosity).

      1. If you want to understand the mathematics in detail, Cornell University’s Waste Management Institute has a great explanation of calculation the C:N ratio of ONE material here ( You’ll notice you need the mass of material (wet weight), the carbon percentage of the material, the nitrogen percentage of the material, and also moisture content (%) of material!

        When you’re mixing two materials, the maths gets even more complicated, and Cornell’s site explains that here for a mix of up to three materials: (

        They also have a calculator that will calculate the final C:N ratio “Calculate C/N Ratio For Three Materials” here: ( but you need actual weights of materials, and the real percentages of C, N and moisture once again.

        Many people make hot compost without ever looking at the maths and it works great!

        The C:N ratios listed here and on other sites are educational and their purpose is to demonstrate which materials have what amounts of C and N to understand how to use each material, and to recognise that that some nitrogen containing materials contain a lot more nitrogen than others, and likewise for carbon rich materials.

      2. Well, I definitely agree with you on that one!
        The very first hot compost a colleague and I tried was a success, and we didn’t overthink the C:N ratios. As Albert Einstein once said ”
        Everything should be made as simple as possible, but not simpler.”
        2 browns for 1 green is as simple (and effective) as it gets. 🙂

  13. If the Berkeley method will compost dead animals, then surely you could safely add some humanure into the mix, which is full of like pathogens.

    It would greatly encourage the composting of human waste if it was made know that it could be safely turned into compost in 18 days.

    I suspect that no one wants to advocate this for reasons of cultural sensitivity or legal liability, but it’s time we thought through this apparent contradiction. The potential benefits are too big to ignore.

    1. I’ve personally never seen hot composting used to process humanure ever, we can only guess at the reasons why. In rural areas in Asia whole countries us it unprocessed straight in the fields where food is grown, but they don’t eat raw vegetables, they cook or stir fry everything, so any pathogens probably get eliminated that way. That’s the cultural safety practice.

      If the site is big enough, human waste can be processed continuously on site with a natural sewage treatment system – aerobic digesters that use bacteria to break everything down, then the resultant waste is passed through reed beds planted in gravel, then what comes out of this if fairly safe and is used to irrigate fruit trees. I believe Michael Reynold’s ‘Earthship’ buildings process all human waste onsite and use the outputs to provide water and nutrients to orchards near the house. Guess this is getting off the topic of composting though…

      1. You can compost human manure you just need to make sure you get it hot enough. You are probably still best to use it for trees or bushes rather then using it on the vegetable garden. I have worked on an organic farm where a retired Environmental Scientist had a system for composting human manure. I read about along time ago how in New England there is some human manure treatment plants where human manure is broken down for compost (using bacteria) and sold to the public. Once any Nasty bugs have been destroyed the only issue I guess would be any medications people had been taking, which might be high in certain toxic minerals.

  14. Thanks for the response. Yes, I know the three stage natural sewage treatment system as detailed in the Design Manual, but in relation just to hot composting, isn’t it interesting that no-one utters the “h” word?

    I have the videos on-sale at the Tagari site of the PDC given by Geoff and Bill in Melbourne in 2005. In it, Geoff goes through the complete 18 day system. He also tells anecdotes about using the system to compost a wallabee, a duck,and road kill of various kinds. Never, though, does he mention humanure, nor does anyone ask him about it. Curious.

    Unless and until I hear otherwise, I’m going to assume that the temperatures reached by this system are plenty high enough to render harmless anything in reasonable amounts of humanure composted in this system.

  15. Hi,
    Thank you very much for this information.I have based my own compost making on the method you have described.Your post explains the science behind composting in an easy to understand manner.

  16. Hi. Great article! Thanks for writing it.

    We’ve been cold composting for years but are now trying to compost, and I have a couple questions about the 18-day method.

    1. We put our raw materials in cube-shaped compost bins that have slats on their sides, and we cover the top with canvas. Is covering a bad idea?

    The reason I ask is because we typically get some fire blight in the middle of the pile, but the heap never gets above 65C. The pile does not smell bad.

    2. The heap consists mostly of rabbit manure: dry timothy hay, pine shavings, rabbit pellets, and some rabbit urine. Does that sound like the right mix?

    I’ll appreciate any guidance you can provide.

    Thank you.


    1. As I mentioned in a previous answer – “The compost heap is normally covered with a tarp or plastic sheet, to prevent the rain cooling it down, since the water penetrates into the core of the compost pile. Cold outside air will cool the surface, but not the core of the compost heap. The covering prevents some heat loss from the surface to cooler outside air, and retain the heat within the compost heap better.” I’ve updated the article to add this information, as this is an important point, so thanks for asking. Short answwer is no, covering is not a bad idea if you want to retain heat and prevent the heap getting waterlogged from rain.

      If the heap is getting fire blight, it might actually be getting over 65 degrees celcius, depends if your thermometere is accurrate enough and long enough to reach the centre of the compost heap without digging it open. Leaving the top cover off for a while will coll it down a bit.

      Your mix includes all the right ingredients to supply carbon and nitrogen, you just have the ratios correct, if the heap shrinks in size, add more carbon, if it’s not breaking down, add more nitrogen

  17. Thanks for the response Blackthorn.

    Do you know where I can get a picture of fire blight? Maybe what I’m seeing isn’t fire blight, because it seems worst on grass, for example, glass left inside the lawn mower will get white stuff on it, too.

    How can you tell if the pile is actually shrinking? Our pile has a good chunk of dry straw/hay, which tends to hold a lot of air, so it’s hard to say if the pile is settling or actually shrinking.


  18. Don’t have any pictures of fire blight, but it’s very easy to tell if the compost heap is shrinking, it reduces in volume drastically. If it’s just settling, it’s only a small change.

    1. Ive been hot composting for about 30 years. I spread it out in layers then run my Troybuilt tiller thru it many times before piling it up. I primarily use leaves and grass clippings but also kitchen wastes. I have never used a thermometer but I know it gets very hot. My question is after reading this Im pretty sure I have been getting fire blight for years. I make many large piles yearly to put in vegetable and flower gardens. The finish product is broke down, looks and smells good. Can you tell me what the problem is with the pile getting to hot. Im guessing maybe mold spores while turning?

      1. If your hot compost is getting too hot, it just indicates that you have excess nitrogen, so it’s best to make better use of the composting materials by adding more carbon-rich materials, such as wood chips, saw dust, dry woody material etc, so you can produce more compost without having any nitrogen escape back into the atmosphere. Green leaves, grass clippings and kitchen wastes are all high in nitrogen, so you need more carbon containing materials. You could collect autumn leaves and store them aside for adding into your compost if you can’t source wood chips, sawdust, newspaper, cardboard, straw, etc.

        The problem with the compost heap getting too hot is that it runs out of oxygen and anaerobic thermophilic composting bacteria take over, which changes the whole chemical process of the composting. Aerobic breakdown retains the volume of compost, as well as a lot of nitrogen, which is a valuable macronutrient required for plant growth. Anaerobic breakdown releases lots of carbon and nitrogen back into the atmosphere, and the compost reduces in volume, as well as becoming more acidic.

      2. I dont feel I have any of the adverse conditions happening. There have been times when the smell (ammonia) would be bad but havent had that issue in years. If the wind was blowing up towards the house my wife would let me know it. I guess my nose is my thermometer but it would be interesting to use a thermometer and see how hot it gets. I have one pile thats about done (17 days old), one thats 8 days old, and started a new one yesterday. I mow two acres with a lot of trees and have a Cyclone Rake yard vac that I pull behind my lawn tractor so I have plenty of material.

      3. I have two composts heaps in dustbins – one to keep filling, the other left to do its thing. This has all worked well enough – the temp in the one I add to is usaually around 35- 40C in the spring / summer / early autumn and produces good compost over perhaps 3-4 months once I’ve stopped adding new material.

        The question I have is about what happpens towards the end of this 3-4 month period. Not always, but frequently, when I look in the bin in process of decomposing, ie not having new material added, the compost is starting to appear or is near completion and yet for some strange reason, when I take the lid off to have a look and see how things are going, the lid and near the top of the bid, are covered with sometimes a few, often loads, of small, wriggling red worms – all trying to escape from the bin, just when I want them to stay in the bin for them to finish their good work.

        Do you know why this happens?

        I have read that it has something to do with too much moisture, but this doesn’t make sense as the heat has generally cooled off a bit and although the underside of the bid lid is a bit damp, it doesn’t seem quite right.

        I usually put those worms that are trying to escape into the more active bin, but suspect others do manage to escape – not that it really matters, I am just curious!

        With thanks



      4. Hi Jonah, earthworms don’t want to be anywhere near composting material while it’s in the process of composting, they only visit when the composting process is completed. Bacteria carry out the composting process in compost bins, and the chemistry in there is not something the worms can tolerate. In summer, a sealed compost bin gets awfully hot too! In worm farms, earthworms come to the surface when the air pressure drops, which happens when rain is coming, thy come up so they don’t drown. Hope this helps!

      5. Thanks for your prompt reply, Angelo.

        So, after all these years, I now realised that worms do not take part in the composting process….How could I have not known that. The ones I have trying to escape are thin, red, wriggly worms, often quite long…. and they are nothing to do with the composting process? How come they are in the manure from the farm when I go to collect it?

        With thanks again.

        Jonah ________________________________

      6. Earthworms and compost worms do their own composting, it’s called vermicomposting, that’s what happens in a worm farm – see my article –
        They don’t produce compost though, they make something far better, the best fertilizer available, worm castings!

        Composting is best for garden clippings, leaves, mulched branches, and lawn clippings, and it’s a slow process taking months, hot composting is the fastest and is completed in 18 days, which is 2/3 of a month . Worm farms only process fruit and vegetable kitchen scraps and a few other things, and consume material daily, it’s an extremely quick process. The worms are in the manure because it’s their job to break it down, it’s what they do in nature! ?

  19. Hi. I have been attempting this method with two large piles. One 8cu meters of horse manure and straw and the other 40 cu m of chicken and wood shavings. They are tarped with black vinyl. The average outside temp in the day is 38c. I turn them with a backhoe. If I don’t turn for 4 days the pile temp will go up to 55-60. The problem is that when I do turn the temp drops to 47 or so and takes a few days to build back up. Thanks!

  20. Thanks for the idea of ducks for the beetles that produce the ginormous grubs I have….soon to be new beetles! Problem with having ducks is that there is a local ordinance against them, and they must be fed daily, which is impossible since I’m living temporarily away from the home/garden while it gets upgraded/ remodeled as I can pay for it.

    I LOVE ducks, and there are plenty in this city at the local parks, but they need both space and water, which I don’t have…even if the city allowed them in the neighborhoods.

    True story from a casual acquaintance of ours who described finding a duck nest full of hatching eggs ..but without the mom: He took them home, nurtured/protected/raised them, only to have neighbors call the local police about their noise.

    He said he had hoped to get them far enough along to release them in the park so he went to court and lied about the situation, saying, “The report you received was all wrong. That wasn’t noise from ducks but from DOGS!” They believed him, buying a little more time, but the neighbors persisted until police visited and took the ducks. Hopefully they released them rather than ate them!

    Thanks again for the good advice.

  21. Great article. I have two big piles of organic matter that I’d like some advice about. First, five bags of hedge clippings that might have some bittersweet in them–do I count them as green or brown? Right now its seems to be both. Wait until it’s all brown? I also have one precious bucket of horse manure that I thought I’d mix with food scraps as starter. The second pile is mostly forsythia that I cut down a couple of weeks ago, and as careful as I was, its even more likely that there’s bittersweet and Japanese knotweed in that pile. It’s basically a giant pile of branches. The good news is that since I’m constructing a woodland garden, I’m don’t even want perfectly fine soil, I just don’t want it to sprout demons.

    1. Don’t wait for the green material to dry out and turn brown, you’re losing valuable nitrogen that way, carbon can be found very easily. Turn the whole lot into a huge hot compost pile to kill off all the weeds, and try to break down all the branches into smaller pieces however you can, mulch them, mow then, cut them up with a sharp spade – the compost works better when all the ingredients are broken down into smaller pieces.

  22. Thanks. I kind of decided to “split the difference” with regards to the pile of hedge clippings. By that I mean I’m just not up for hacking up all those twigs. If you’re not familiar with the obsequious American hedge, you should know the twigs are pretty springy, going at them with a hoe wouldn’t work. I’d guess they’re 70 percent nitrogen; add in the leaves on the twigs, and my 2 m around pile might be too green if it weren’t for the larger twigs and the fact that it did die down a bit. Now it’s a 1 m tall twiggy donut with a horse manure-food scrap center! On Sunday I’ll turn it for the first time and decide then whether to add some cardboard.

    My “bittersweet” neighbor has expressed some dissatisfaction with her cardboard and branch yard, so I’m going to leave it be.

  23. Hi

    Have just retired to the beautiful and remote Creuse department
    in the Limousin in France. Have bought a 6 acre plot about half is mixture of mature oak and Beech, there is a lake of about half an acre and the rest is neglected long long grass which i am very slowly taming with strummer and mower. We are vegetarian and plan to start growing as much as possible next spring so am composting everything in sight as fast as possible to help fill raised beds. I am passing everything apart from grass cutting through a broyeur (shredder/chipper) so apart from the cardboard “removal boxes” its all very small. Two heaps so far about 4m2 each. The first i didn’t water enough so was running at about 35-40C The second I did and its at 65-70C, even 60C just 2-3 inches in – both have the same sort of mix. I turned the first heap today and watered as I went so expect temperature to rise. My problem is I have a bad back and the turning today which took about 90mins has left me with a lot of pain. I just cant see me repeating this on a 2 day turnaround, especially with several heaps. I would appreciate some advice to ensure readiness for next spring with the minimum of back pain! Thanks for a brilliant article.

    1. Hi Chris, I would use smaller compost heaps, something closer to the size recommended in the article, around 1 metre square and a bit taller than that. A 4m x 4m x 1m pile is huge! That’s back-breaking work in anyones language, sound like something you would tackle with a front-end loader!

      Smaller heaps are much easier to turn, around 15-20 minutes. Since you have to complete turning a heap once you start doing so, if you have several smaller compost heaps, they are much quicker to finish, so you can have a rest much sooner, that way the work is not as tiring and drawn out as turning one big heap.

      Furthermore, by having multiple smaller piles, you can have a good rest after finishing each one, and when you are refreshed and re-energised, you can tackle the next. Thos allows you to spread the work out over the length of a day. For example, you could turn one heap in the morning, then another a few hours later, and so on.

  24. As predicted after 2 days, the newly turned first heap is hitting the heights at 65-70C the first and previously 65-70C second heap is falling back to 50-55C

  25. Haha – no 4X4X1 would be 16m2 mine are 2X2X1 but still twice what you recommended – will give smaller ones a go though, it will help I’m sure – thanks

  26. Ah-hhh, our dreaded Texas summer is cooling down, but “the whole state has been plagued with mosquito-carrying West Nile Virus, causing a fairly large number of deaths.” Being so efficient, the city officials? or some authority has sprayed the entire STATE with ‘relatively harmless chemicals’ THREE times over a few weeks, causing a noticeable dullness of life in everything living.

    It certainly put the skids on gardening hopefuls, and likely gassed
    the many compost piles in the making with their concoction of only God knows what! [ Right away we found a poor dead Morning Dove who’d been feeding from the neighbor’s tossed bird seeds. So much for “harmless”.] Now I’m wondering how many more creatures will go the way of the bees -which have all but disappeared here ov er several years now!

    My grub problem has not changed, yet the lawn in the temporary
    home I’m renting has signs just like my other home-in-repair of grubs beginning at the edges of the lawn!!

    With all of the genetic modifications/ mutations/ hybrids/ cloning,
    even science [and Monsanto] likely doesn’t know or care what all they’ve altered/ created, much less how to rid our land of such things. We’ve sent more soil samples to the state agricultural extension center for analysis, waiting for some suggestions before blow-torching the remnant sparse stubs of well-established noxious weeds, wild carrot and wild garlic, which the omnivorous zombie grubs seemed to have rejected!

    Yes, this sort of global bio-manipulation tends to make one pessimistic, frustrated, as well as outright ill. Although there must surely be myriads of researchers who have hopeful suggestions, but our arms and pockets are fast becoming empty for such challenges that are not of our own making/ budgeting.

    The lawn responded to the first application of “recommended” [against my better judgment fading fast] Golf Course chemical fertilizer….for about a month, but our cheering it on, watering to near indebtedness to the city utilities, manicuring to an ‘exact science’, the results is nearly the same as before we started.
    Luckily our property is not at all the only affected one.

    Thanks to you, Julie, for the duck suggestion last July, but our city deed restrictions/ homeowners’ association refuse to permit us to have such helpful creatures within the neighborhoods. I still have my house-chicken and mini-Rex house-bunny in lovely large well-built rolling cages, but cannot let them freely roam outside, even inside my fence, because of the wild creatures the city protects – and which are attracted to and eat such animals. We have Owls, Hawks, O’possum, Raccoons, occasional foxes, Coyotes, abandoned domestic and exotic animals turned loose when someone moves, and hefty resident rats which are said to eat
    the feet of chickens as they sleep!

    So why am I writing? Just in case someone runs across another
    soul like me, who might have an alternate solution to the blow-torch, [which would only take care of the tough dry stalks which we have also considered spray-painting GRASS green! lol If some of the local landscape companies can tint their seeded foam, it would be a big temptation even for you!]

    Wish I could send a photo of it but we still have a few large spreading and tall old trees making a photo near-impossible. Hum-mmm, anyone know whether too many fallen acorns can ruin lawns over the years? We’ve always just mowed over them. They likely just fed more grub-bellies, right? Wouldn’t this scenario make a good video/board game : “Conquest of the Zombie Grubs”
    with a sequel: “Protectors of the Zombie Grubs”.

    [My grandson would likely want to develop this whole concept since his goal is to be a computer animation programmer of new games for teens and young adults. He’s currently reading every Anime book he can find for ideas. I’ll suggest this to him tomorrow and have my cellphone camera set for his laughter!] I may as well laugh, since I’m nearly out of tears, hair, and money!

    1. Hi, to be honest I’m not sure what your point is here in regards to hot composting, if I did I’d try offering some help…

    2. I know its some time ago this post was made, but why not abandon the lawn, If nature doesnt want it to grow, do something else with it. Grow what grows well is my adage where slugs and clay make growing a nightmare unless I follow nature.

  27. Oh, might I suggest that NO one add litter-box residue [fresh or otherwise] nor ‘roadkill’ to their compost, because of the good possibility of diseases. You were just kidding, right, when you mentioned, “anything” can be added to the hot compost?

  28. Our good neighbors began a compost pile the lazy way by just tossing all grass and a very few veggie scraps into a pile over a couple of years. [ It became the S.W. distribution of flies, rats, and whatever else since it was, to my knowledge, never turned by hand, but did indeed turn to blackest dirt.]

    My son agreed to build their new fence when he built mine, with the understanding that he’d single-handedly move their pile to fill in our holes left by larger tree roots, to which they agreed.

    Within a few weeks, one of the few veggie scrap SEEDS sprouted and grew the largest, most delightful Acorn/ Winter squashes we’d ever seen . I collected six large ones, stopped by to share with them but they’d gone on vacation, followed by our doing the same, and never got to see them before we had to eat them. What a wonderful surprise with a supportive message: Seeds can indeed
    survive most bountifully any compost pile, neglected or tenderly tended. I have chosen to be MOST careful to prevent my adding seeds of any sort to the next pile on the horizon.

    1. No, seeds do not survive hot composting, what you’ve described is cold composting, and yes, some seeds will grow from cold compost, which is why, as a rule, you should not cold compost any weeds with ripe seeds.

  29. The best article on hot composting I have ever read. It all makes sense now, thank you so much!
    I now understand that our heap is too high in nitrogen due to the large quantities of grass clipping plus chicken manure. It is getting very hot and getting fire blight. It is almost like it burns itself out and then cold composts from that point on. We ended up with some reasonable compost in the end but it takes a long time and wasn’t all fine and unrecognisable like you describe. Definitely going to do it this way from now on.
    The only bad part with doing it properly is having to go out in the pitch dark at night to turn the heap. The perils of working full time in the city I guess.

  30. Dear sir: thank you for a very clear and concise article on hot composting. I have lived in Asia for 22 years and I’m developing a system for composting of humanure into humus for home and industrial agriculture in developing countries. My UDDT system separates human solids and liquids for several reasons & you finish up with two vital products in humus & NPK (urine) In India alone there are 600 million people a day who open defecate in fields because there is no (and never will be) organised governmental sewage collection system. Therefore collecting and utilising human waste products on a micro and macro scale has huge benefits in terms of ecological, geological, economical and human health and dignity aspects. I came across your wonderful site because I heard of hot composting and wondered if it could be utilised for humanure?
    A couple of points about the western phobia about growing vegetables in human ‘poop’

    If you think you are growing vegetables in human waste you are not; you are growing in organically rich humus, which, when properly processed through aerobic thermophillic composting has killed off pathogens at a temperature way beyond what the human body takes to kill of its own pathogens; in addition, it has also gone through the vermiculture process. You should worry about using industrial ‘fertiliser’ a.k.a. toxic waste, not humus a.k.a. organically rich compost.

    Is it safe? Yes, according to WHO standards.
    Faecal pathogens are dead after one week of composting at a sustained temperature of 122 f. When processed / composted properly from humanure to humus the compost contains no harmful pathogens. (WHO) Thermophillic composting often produces temperatures of around 150 f.
    In addition I have been in contact with several members of the SuSaNa forum who have been growing in humus and using NPK (urine) for agriculture & salad plants for many many years.

    FYI: Asians DO eat uncooked salads, quite a lot nowadays, as do I, but also extensively wok-cook / stir fry veg”s like beans, cabbage, carrots etc.

    I will share with you once I (eventually) have my web/blog up and running. You should definitely put a programme together and go out and teach it in schools / community centres etc. We can save on fuel, carbon and land fill etc etc by taking personal responsibility for our waste products. Spread the word!

    Best regards

    1. Composting human waste is a very good idea. I think a better one is to put both kitchen waste, urine and human waste into a methane digester to produce methane for cooking to not cut down any more trees and reduce indoor pollution and you also get a very high quality of fertilizer that you can put right on the land. This is something some Chinese have used for hundreds of years to keep their field fertile without soil depletion.

      I hope this has been helpful.

      Richard Boettner, Tomorrows Vision

  31. I am trying to hot compost using shredded oil palm fronds which are half dried, peat soil as bulking agent and chicken manure. Can i use your method with these ingredients?
    Will adding some compost activator help in the process?
    I am located in johor, Malaysia with tropical temperature and climate.
    Appreciate your reply.

    1. It should work fine, as long as you have the right amounts of carbon and nitrogen containing materials, the bacteria will do the rest. Using a compost activator always helps, you can use comfrey, yarrow or nettles. Or you can pee into the compost heap! Adding a small amount of mature compost always helps to ‘inoculate’ the compost with the right bacteria. Give it a go and let us know how it goes!

      1. OK, pee into the compost heap is fine, but how much pee will it take to destroy my compost? I can get all my family members to pee in it.

    2. You only need to add a small amount of any compost activator once, it justs helps get the compost started. So, in answer to your question, one person, once, is plenty!

      1. Will let you know the outcome in 2 weeks time since I am starting the process this thursday. And will as much as possible, follow your proceedures. thanks mate.

  32. Hi,planning to build a hot compost while winter will come soon is it a good ideea?! Covered,outside or covered ,inside a part of greenhouse wich will not be used during the winter? if yes,what kind of manure is better to use,fresh or from the last three months? of course,will try to use activators but the problem is fresh manure or not? the temp will be soon below 30f(0 celsius)…
    will try to increase the ratio of carbon till 40:1,or should i let it 25:1 ?! will be cows and horse manure….
    From Romania,with admiration and respect for your work !

    1. Hi Cris, to be honest, I’m not sure if the hot compost pile will cool down too much during such cold weather, because our weather never gets that cold here, so I would only be speculating.

      Covered up, and inside a greenhouse should work, and it will warm the greenhouse too for a short time. Fresh compost will be the ‘hottest’ because it contains the most nitrogen, the aged compost will still work well though.

      Don’t change the C:N ratio, because that is the ration that is used to make up the bacteria’s bodies, and it’s their activity that generates the heat. Excess nitrogen won’t be utilised and will probbaly just be released from the compost heap as ammonia.

      It’s really a matter of timing, if you you can make the compost (in 18 days) before the weather gets very cold, then all will be fine to build it outside with a cover. If you want to make hot compost in freezing weather, all you can do is try and see what happens.

      In Permaculture, we work with the cycles of nature and the ‘wild energies’ moving through our system/site – and one of those energies includes the natural heat from the sun. I would assume you would have the most materials to compost in autumn with leaf fall from deciduous trees, and green waste from your summer annual plants after harvest. This would give you some time to compost before the winter cold set in, and you only meed 18 days to do it!

      1. First attempt failed in glory! 🙁
        Succeded to rich few spots of 55 grdC ,but ,lack of personal presence for aeration ,…leading to a expected failure !
        Now,spring is come again ,with fresh energy and more achievements!
        Keep in touch!

      2. I gave it a go. With so many autumn leaves it was silly not to. Tempatures this week are below freezing and I think it’s stopped the process. Yesterday while turning the pile for the 5th time on day 13 I didn’t see any steam like I had the times before.

        I have been covering the pile. I’m curious if there are things I can try to get it going again?

  33. Great article! Thanks. I have a question:)
    Will pomegranate peelings break down as quickly as other “green” materials? It happens that I have plenty of them but also need quickly a lot of compost. Was wondering if it’s ok to use the peelings or should clip dome grasses? I really need compost in 3 weeks and as I have no experience in gardening/composting I thought I would ask:)

    Thanks, Sebastian.

    1. When hot composting, everything will break down! You’ll need to mix them with other ingredients as per normal hot composting practice. If done right, the ingredients will just vanish and create fine, dark, rich compost.

  34. Blackthorn wrote on July 29, 2012 at 1:34 am:

    “Ratios of carbon to nitrogen are the LEAST critical in a compost TUMBLER. Technically you could compost green grass clippings alone as long as you turn it daily, but its best to add a good mix of materials to try to achieve the optimum C:N ratio.”

    [Emphasis added.]


    I’m preparing a 58-gallon black plastic drum (once used to ship cucumbers in brine) for composting, and have a question about the air circulation.

    There’s so much emphasis on the C:N ratio on the Web, but John Paul, Ph.D, P.Ag. (, a noted compost researcher, also told me that in a TUMBLER, that ratio is less important than air circulation and moisture content. This confirms Blackthorn’s comment above.

    Dr. Paul was too busy to give me specific advise about the number and size of holes to drill into this 58-gallon tumbler, so I’d appreciate your advise about that.

    I intend to turn this barrel on its side and put in and take out the materials from the “top” end, which is a “bell jar” type design allowing one to open it by screwing and unscrewing the (entire) top.

    I’d like to drill the holes only on the “original” top and bottom. Is that a good idea? (I don’t want to drill holes in the “original” side because that will allow all the “compost tea” to drain out onto the ground, and I want to drain out the “compost tea” into a special bucket only occasionally, using a single hole (with an on/off faucet fitting).

    Thanks so much.

    1. Definitely drill holes only in the top and bottom so you can collect the ‘compost tea’ liquid.

      My tumbler compost bin is a commercial (bought) one, it has four holes on the outer edge of each top and bottom end, 8 holes in total.

      The ‘holes’ are 3/4″ (19mm) in diameter, but aren’t really holes, they are a line of five slits that make up a circle shape. I’m guessing that’s to stop flies and other undesirable insects from getting into the compost bins.

      However you make the air vents, make them up with a series of small holes if you can.

  35. Hi,
    We made a compost pile with mostly sheep manure mixed with some left over hay that was mixed in from what the sheep had eaten. But in the end it was mainly manure. We didn’t add much else. The pile is 6 ft high and 10 ft wide. We turned and watered it once a week for around 6 weeks. The highest temp we reached was 122 degrees and then the temp went down to 110 and we can’t get it much higher. It is turning black and the sheep pellets are decomposing. With our organic certification it is required that we reach 131 F minimum for 15 days. But we haven’t come close. I realized we probably didn’t have enough carbon so we added two bales of straw to see if that would help. But so far the highest temp is 110 F. Should we add more straw in layers between the current compost pile or is it too late because a lot of the manure has already broken down? We have the pile covered with a tarp as well.

    1. Hi Tina, that’s because sheep manure is low in nitrogen compared to other animal manures, plus side is that it won’t burn your plants, minus side is that it’s not the best source when you need lots of nitroge. Hence the recommendation to use a mix of ingredients in your compost. Hope this helps!

  36. If you could answer my Nov. 25 post, I’d be much obliged. This weekend I’ll be setting up the compost barrel system and need advise about the wisdom of drilling the “circulation holes.” On Nov. 26, Mary Schwarz at the Cornell Waste Management Institute advised against drilling any such holes and instead to ensure that the materials I use — she recommended “wood shavings” that contain much air / oxygen in lieu of “saw dust” — are carefully measured with the coffee grinds in the proper proportion. But I’ve never heard of a compost tumbler with NO circulation holes!

    1. I’ve answered your original comment, please see above. The tumbler bins, and all compost bins for that matter, rely on aerobic composting, they definitely need oxygen, otherwise they go anaerobic and stink! You definitely need air vents!

      I would only keep it airtight if I was using a bokashi fermenting anaerobic system, but that doesn’t need tumbling. The point of tumbling the compost, moving it, turning it, etc, is to get air into the mix to speed up breakdown!

  37. Thank you for your responses. I’m still confused about where are the holes in your composter, since “top” and “bottom” and “side” are unclear to me. Can you tell me what is the model and manufacturer of your compost tumbler? That way, I can go and see a picture of it on the Internet / web site of the company.

  38. Ah! Thanks so much! I can see from the video and the photo that the holes are precisely where I’ll put mine — on the “ends”. The difference in the “Tumbleweed CompostTumbler” and my home-made tumbler is that, if one considers all tumblers to be a “cylinder,” the “Tumbleweed” operates (spins, tumbles) “vertically” and mine will operate “horizontally.” The video doesn’t discuss the problem (or benefit, depending on one’s viewpoint) of excess moisture inside the tumbler that may create “compost tea” that must be drained off. One manufacturer of a “horizontal” design tumbler solves this problem with two “compost tea” drainage holes in the door. See I will not have any such “door” however; I will have the same sort of screw-on, screw-off “top” as “Tumbleweed” and will drain off any extra water or “compost tea” with ten holes, drilled in a line along the bottom of the barrel, each about 1/4 inch diameter, with a “catch basin” underneath to “catch” any “compost tea.”

    1. Since my compost tumbler drains out the liquid from the lids, especially in the rain, I simply collect the compost tea by placing a plastic garbage can lid (the thick solid ones) underneath it, works well!

      1. If you exclude rain water, how much liquid typically drains from your tumbler? That is, how much water does your compost accumulate on its own? Does warm weather cause much or any of it to evaporate through the circulation holes?

    2. Im not sure because my tumbler compost bin sits out in the open, it would depend on the water content of your composting materials.

  39. Thank you!!! It sounds like I was going the wrong way with adding straw and increasing carbon. You mentioned low nitrogen for sheep manure and thus low temp, so if the pile with the sheep manure has already decomposed quite a bit is it to late to add things with more nitrogen ? Would it be better to start over with a new pile of more of a mix of ingredients to get the hotter temps of between 131-170 and to use this current pile as a manure amendment rather than compost? Or can I add more ingredients now?

    Thank you,


  40. “Compost Starter” question.

    Many university extension service offices say that all living things have the necessary bacteria to cause decomposition.

    However, the primary components for my compost tumbler will be two: wood shavings and coffee grounds, and neither of these seems particularly endowed with bacteria.

    Where I live, there are few chicken farms but many horse stables.

    Should I expect any more success (i.e., progress in composting) by adding chicken or horse manure? If so, how much if my barrel is 58 gallons (220 liters) and I put into it, at one time, all ingredients?

    Also, how full should I fill my tumbler by volume? one-third? one-half? two-thirds?

    1. “Variety is the spice of life…” and is essential to a good compost too! Manure would be more like a third ingredient, which will be better. I’ve alreay mentioned the compost activators/starters in step 1 of the instructions.

      When using a tumble bin, I aim to fill it almost all the way to the top, usually about 75% full all at once, you need to leave enough space for it to be able to tumble and mix around.

      1. I just got for free for my compost tumbler about 250 pounds of chicken manure from a man who grows chickens for the eggs he sells.

        Some of it is “fresh” but most of it is “old” — that is, we dug it up with a shovel from a heavy, dense pile, parts of which smelled quite bad.

        For “bacteria activation” in my compost tumbler, I had thought such “fresh chicken manure” (that I get FREE) was supposed to be superior to

        — “Black Hen Composted Chicken Manure” — described at — (20 pound bag costs $8)


        — “Black Kow Composted Cow Manure” — described at — (50 pound bag costs $5).

        (I presume that anything composted has less bacteria than the raw materials that created that compost because it has gone through a “hot” process that killed certain valuable bacterias.)

        I e-mailed the Black Kow people about this and got the answer below, which seems contrary to what I’ve read on the Internet.

        I’d appreciate any reaction to the statements from Black Kow.

        If you were me, would you use for a tumbler composter “activator” FRESH chicken manure, COMPOSTED chicken manure, or COMPOSTED cow manure?



        Dear Jock:

        [. . .]

        Chicken manure will supply nitrogen to the compost, but not a lot of bacteria. A bag of Black Kow cow manure would be a great source of bacteria.

        [. . .]

        Fresh manure will contain a lot of good bacteria but also a lot of bad bacteria that could cause odors if not composted properly.

        [. . .]

        Cathy A. See
        Black Gold Compost Co.
        P.O. Box 190
        Oxford, Florida 34484


      2. Today I received a followup e-mail (below) from Ms. See at Black Gold Compost Co. Is her statement about “good” and “bad” bacteria for composting correct?


        Dear Jock,

        Fresh manure will have more bad bacteria since it is not composted.

        By the time we compost the product and bag it, the bacteria has been killed.

        The product composts at such a high temperature that it kills the bacteria and weed seeds in it.


  41. I started my hot compost BEFORE finding this site. I have included layers of rich dark soil between my green and brown layers. The soil had many beautifully large earth worms. Am I going to cook them or will they retire gleefully to the bottom of the heap as the temperature increases?


    1. Hi Chris, I’m guessing that if earthworms can rise to the surface when the barometric pressure drops (signalling rain) so they don’t drown, they would hopefully similarly respond to increasing temperatures and burrow down into the cooler soil. This is only speculation on my part!

  42. I am calculating the carbon to nitrogen ration of composting cardboard and coffee grounds. I come up with .54:1. Does this mean .54kg of cardboard for every 1 kg of coffee grounds? Is their a volume formula out there and not a weight formula? thanks for the quick reply.

    1. Basically, if you’re working with volume, to simplify things, aim to use 1/3 green/nitrogen containing materials and 2/3 dry carbon materials. In other words, one bucket of nitrogenous material to two buckets of dry carboniferous material.

      For example, cardboard has a C:N ratio of 350:1, and coffee grounds have a C:N ratio of 20:1.
      If you want to work it out mathematically, you need to take into account the moisture content too, which complicates things. I found an online C:N ratio calculator at and using your ingredients, with a simple 2:1 of cardboard to coffee, the calculated C:N ratio was 40:1, which is still ok, the fact is they rate coffee as 13:1, while my sources ghave it at 20:1, resulting in a final ratio of 41:1. Really, there is a lot of variation between materials, so it’s not exact. This example just shows how the ‘rule of thumb’ of two buckets dry : one bucket green can be fairly accurate.

  43. thanks for the quick reply. that makes sense. Would the 2 buckets brown 1 bucket green work for leaves, too even though leaves have a c:n ratio of 60 to 80:1? I have also read 2 greens to 1 brown. anyway, thanks for the reply.

  44. I am investigating setting up a hot composting unit to take the grass cuttings from a large garden (3 Acres) Would a hot composting unit 2.5 meters square and circa 1 meter high be too big.

    1. If you can turn it easily, then it’s not too big, otherwise make several heaps of a manageable size.
      If you turned it with a front-end loader, it would be very easy! That’s how they turn hot compost on a commecial scale!

  45. I am composting shredded leaves and poultry manure. when i plug in 1 cubic foot of poultry manure to 20 cubinc feet of shredded leaves into the compost calculator the computer says 1 part poultry manure and 20 parts leaves and am only getting a 23:1 carbon nitrogen ratio. so this means 1 bucket of poultry manure to 20 buckets of shredded leaves, seems like too much carbon. any clarification would be nice, thanks

  46. What a great post. I started my pile 4 days ago but realized I seriously underestimated my horse manure so the pile was too small. However, I still added urine to activate the pile. So 3 days ago, I picked up some more horse manure and added it to the pile- layering- with more straw (aged straw) and leaves. I am not sure that my pile is big enough since of course the laws of physics do not allow for exact blocking of the pile and it often settled and slipped during the process. So I am really unsure if my volume is correct. Also, I live in New Mexico and we have had a really cold winter these past few weeks so the poop was cold, the leaves are a bit wet, and the straw was cold. I took the pile’s temperature with my 20″ thermometer today and yesterday- it remains at 32 degrees F. Am I doing something wrong? Is it supposed to read around the “hot” temperatures during the first, second, and third days?
    Thank you so much,

  47. If temperatures stay low any heat is immediately lost and the pile does not cook, heat up enough. Wait until you have warmer temperatures and in no time you will have compost.
    Don’t forget you can add all of your kitchen waste too and I highly recommend it. Stirring a pile will also help speed up the process of turning it into great soil.
    I love composting.

  48. One more thing: Everyone can continue to add to their compost pile, bin or whatever throughout the winter. There is no reason to not continue just because it gets cold. (Extremely cold climates are an exception.)

  49. Julie never let us know if she got her pile composted in 18 days or how long it ended up taking 🙁 Anyone finding they can do it in 18 days?

    1. I helped a friend build a hot compost pile when we first learned about it, and it completed in exactly 18 days, that’s why I wrote the article!
      Mind you, we ended up with a cubic metre of compost, which was a lot for a tiny courtyard!

  50. Great write up, I’ve trawled through many a site detailing composting but none have outlined it in such step by step detail and known pitfalls as yours. Thanks!

  51. Thanks for the article! I read through almost all of the comments and I didn’t see anything about when the compost can be used. Most of the articles I’ve read have mentioned that you should let your compost “cure” after it finishes otherwise it can burn the plants, and I’m wondering if you have advice on that.

    I’m in cold Minnesota and despite the 10 degree weather my pile is already 80 degrees, 3 days after putting it together! It’s getting pretty smelly though, so I’m guessing I need to add some more straw to my pile, and that might cool it off quite a bit. Oh well, not too bad for this time of year!

    1. The compost is ready to use as soon as it’s finished, in 18 days from when you first construct your hot compost heap! All properly made compost will not burn plants and should not require any curing process. I can only imagine that if a compost uses a lot of really ‘hot’ manures that haven’t broken down properly, it would be like adding the manure straight to the plant, and some nmanures will burn plants. You do’y have to worry about this at all. Properly made compost is gentle on plants, you can plant seeds and seedlings into it without any concerns.

  52. Is there any way to “supercharge” your compost before putting it out into the field? Any value to adding biochar, urea, or anhydrous to the process? If adding compost to alkaline soils, ph 8.0, is there a process to make your compost slightly acidic? Thanks for all the good work.

    1. You’re welcome!

      No need to do anything to your compost, it’s already “supercharged” with life, it’s packed with lots beneficial living organisms which will enrich the soil and help your plants grow, and compost contains lots of nutrients in natural concentrations or levels that won’t burn your plant’s roots.

      If you add any chemical fertilizers such as Urea or Anhydrous Ammonia directly to the finished compost (or even into your soil) you’ll kill all the life in the compost (or your soil), which kind of defeats the purpose of using compost and gardening organically in the first place.

      Fast/hot composting creates a slightly alkaline compost, slow compost creates a slightly acidic compost. If you want to make the soil acidic, don’t mess with the compost, just use plenty of mulch over the soil surface which will slowly break down, and if you really want it very acidic, for growing blueberries for example, mulch heavily with pine needles around the plants.

      Compost works on its own and doesn’t need biochar either. Just dig you compost into your soil or place it on the soil surface, but under a thick layer of mulch so the soil life can get to work and the nutrients can leech into the soil.

      Keeping it simple really is the best way to use compost!


  53. Hi, I have just found this site, brilliant advice! I have a hot compost heap on the go now, I am not particularly worried about it taking 18 days, as I can’t gather the materials to replenish in 18 days either. So my question is, will my pile naturally cool down as it becomes ‘ready’ (or as the nitrogen runs out)? Or can i keep it hot by adding more nitrogen periodically and is there any benifit to this? Is there a definitive way to be sure that the composting process is ‘over’? Thanks for the advice! Jon

    1. Hi Jon,

      There is no need to gather more materials to ‘replenish’ unless something goes wrong, most of the time, once the compost heap is built, nothing else needs to be added, it only needs to be turned as described, and when it cools down after the 18 days, it will be ready. There is no benefit in keeping it running hot any longer, when it’s ready the bacteria will have used up both carbon and nitrogen, not just nitrogen alone.

      After 18 days, you will beyond any doubt know it’s ready, as the compost will be fine, dark, and rich, much finer than any slow/cold compost you’ve ever made.

      If, after the 18 days, you want to keep composting, I recommend you leave the completed compost alone and build a second compost heap!

  54. We have a very large manure pile on our acerage, mostly cow, some chicken and goat and lots of hay and straw mixed in. We had to bury our cow in the pile when she died last week (no diseases) and I am wondering how I could go about breaking this all down as quick as possible, it is also winter still here, -20c sometimes at night. I would prefer not to have to disturb her body as it decays or stir up any smells it may give off….can anyone help?

  55. I have a three challenges that could benefit from some group think–not enough nitrogen material, no ready access to water, and cold weather. What I have is plenty of leaves and snow, a trash bag of bunnie poop and carbon bedding, and about a bushel of–what do you call it after worms do their work? It’s great soil, but does it qualify as “nitrogen” for the purposes of hot composting. And if I layer snow in with what I do have, will it melt and make my pile wet enough? I think I’m going to start on Friday, USA. Great site, thanks muchly for keeping it up.

    1. Day 1. Ok, so here…I’ll find a way to post a picture–it is; a layered heap of oak leaves, snow, and grass mixed with bunny poop and worm castings. The down side is the lack of water, and maybe too small a heap. The up side is the high quality nitrogen. I’m not really sure if I got the ratio or thickness of the layers right. It’s supposed to rain/snow and so that could be a good/bad thing. I dithered quite a bit over whether to put it under the wooden fire escape and kind of split the difference by putting it near the border on some rocks and a slight slope. So, if there is too much water it will drain and if not enough…well, that’s the rub…and I guess I can’t post a pict. Maybe on my blog. I’m way to excited about this.

  56. Hi, great article. I am trying my hand at composting and gardening for the first time ever. I bought a plastic bin and have layered dried crushed leaves with kitchen scraps (many of which were already breaking down) and coffee grounds in it. I wet it and mixed it. I rent and hope to move soon which is why I didn’t dig a whole. Will hot composting work this way and should I keep the lid on or off?

    1. Hi Teresa, a compost bin is too small to hot compost in, they can’t hold enough compost, you need to use a cubic metre or more (> 1000 litres) for hot composting.

      1. I have read a lot of your replies stating that a small compost bin cannot be used for hot composting. My question is that I live in Las Vegas and was hoping to utilize the extremely hot summers to start a hot compost bin. The temps this summer have been around 105-115F. Is that enough to be able to hot compost in a 10gal trash bin? I rent and have a fairly small area to work with but I would really like to compost in a way that doesnt attract bugs (specifically roaches). This will be my first attempt at composting. Would cold composting be the best method if I am looking to be able to add kitchen scraps and other materials to the bin regularly?

      2. Hi Michele, hot composting is a biological process that has critical parameters for it to operate correctly. If you need a compost bin around 10 gal in size that will make compost quickly in summer, doesn’t attract pests, and that you can add materials to regularly, then the perfect compost bin for that purpose is a tumble bin composter. The ones that stay horizontal and spin on the long axis, like a jar rolling on its side, are the best to use because they’re the easiest to turn, and if you get one with two compartments, you can have one part filling while the other is full and processing. I’ll have to write an article about these tumble bins soon!

  57. I live in iowa, and right now the highs are in the mid forties, can i still do this or do i need to wait until the summer when its warmer?

    1. If you keep the compost pile covered and keep it running hot it can be done, it’s just easier in warmer weather!

  58. I have grass clippings available at the moment, but not much else. Would it be an option to layer the grass with completed compost rather than laying it with other carbon sources like straw and manure etc?

    1. Layer the grass clippings with newspaper, cardboard, unbleached and unprinted paper, dry leaves, mulched branches and twigs etc. Completed compost layered with grass wont really work, a source of carbon is required.

      1. I do have some cardboard and newspaper, but when I did cardboard a while ago, I found it to be a pain when trying to turnover the compost, so I wasnt going to use it again. Any one have any good methods of the best way to incorporate newpaper and cardboard without spending to much time on it?

      2. Paul, I agree, the problem w/newspaper and cardboard is that it’s time consuming to shred. I tried this w/slight success: at the end of last summer I put a layer of cardboard at the bottom a of drainage ditch by my downspout and then put a layer of leaves on top of it. I didn’t turn it until a couple of weeks ago. It was partially decomposed. Since a lack of ready access to water has been a barrier to me hot composting, I might try putting my hot composting pile in the same ditch. I know that doesn’t really solve your problem, but that’s what I did w/my cardboard! A

      3. The trick with newspaper is to take the sheets and crumple them into tight balls without tearing them up, they help with aeration of the compost this way and provide a source of carbon. Works great with regular cold composting too!

        With cardboard, tear it into pieces by hand, it shouldn’t take any longer than 15 minutes to tear uo enough cardboard to have more than enough for a cubic metre sized compost pile.

        A word of caution, I wouldn’t use too much corrugated cardboard though, the glue contains boron, which is meant to be only a trace element in the soil, too much is toxic to plants.

        To be honest, it’s actually rather strange to suggest that sources of carbon are hard to come by. In a planet filled with carbon based life forms, theyre everywhere around you, all the time. Gather fallen leaves in the autumn/winter period and put them aside for composting. Twigs, branches, dried plant matter and garden prunings work well as a carbon source. Break your materials up into small pieces it if you can use a mulcher, put it on the ground and mow over it, or put in on the ground and chop it up the best you can with a spade.

        Remember, the greater the variety of materials that you use, the better the compost. I would seriously discourage the idea of attempting a two ingredient grass and cardboard or grass and newspaper only hot compost. You might as well just spread the lawn clipping straight on your garden if there are no weed seeds in it, or compost the straight lawn clippings in a tumbler style compost bin that you spin around by hand.

        If youre going to make the effort to make hot compost, it pays to make the effort to gather a range of ingredients first.

  59. Hi, It is wonderful site to learn small but very useful thing. I am in India, Gujarat, I have plenty of vegetable oils waste. Do I use this as a ingredient of composting green materials?

    1. Hot composting is a system for recycling solid waste material, not liquids like vegetable oil.

      Waste vegetable oil is recycled around the world to produce biofuels, it is refined into a diesel fuel replacement for motor vehicles, and also into biofuels used for power generation and heating.

    1. It wouldn’t work as well to use compost bays that wall the heap on three sides when hot composting because with the Berkley hot composting system you need to be able to take all the compost from the outside of the heap first (from all around it) and then pile it up in the new spot to create the centre of the new heap. After that you then put the most composted material that was in the middle of the pile on the outside of the new heap. Essentially, you’re turning the compost heap inside-out! With three sides enclosed you can only access one side of the outside of the compost heap, so you wouldn’t be able to move all the outside material first.

  60. Fantatic information – many thanks !! I have a question I hope you can help with – I am planning on starting a heap and have plenty of carbon (dried leaves) etc and sheep / chicken manure and was wondering if I could dispose of my out of control blackberry bushes in this process as a green nitrogen source ? Would this be effective or suggested to do, or am I putting myself at risk of spreading the bugger further in my garden ? My thoughts were to layer it as a green source alternating with the manure and dried stuff and even pour a bit of urine on it for good measure ?

    Many thanks for your advice

    1. The blackberries should break down nicely in a hot composting system, but you’ll need to add extra nitrogen as the blackberries are a fairly low source of nitrogen, they would fit in the category of “Garden waste” with a C:N ratio of 30:1, too low to use on their own as your sole nitrogen source. You’ll need to add lots more nitrogen as the dried leaves you’re using are a fairly high carbon source with a C:N ratio of 60:1.

  61. Many thanks again for your advice – I am very new to this all and find your site excellent. I will take on board what you suggest with the extra nitrogen – might get some extra cow or horse poo in addition to my chicken and lamb stuff I already have from my own farm. My main concern was the blackberry canes mulched up and used in the mix would flourish (being so evasive) instead of breaking down. I would probably suggest that cold composting them would not be advised, but wasnt sure about hot composting. If I can put them to good use like this – then all the better !!!

    Many thanks again – great stuff

  62. I love this info! Our school currently uses a method very similar. And have 3 hot composts and a vermicompost. We also use pencil shavings once a week. I was reading your blog re water collection. We are collecting condesation runoff from the air conditioning units.
    Thanks for your great insight!

  63. Hi I found your site by pure luck – my husband and I are building a compost heap and I have quite a lot of brown leaves and some green freshly mowed grass. My question is I also have some raw meat that I would like to compost in this heap. I have read your instructions and know to make layers 5cm thick each and to put kitchen waste in the middle. After 4 days when I am moving the heap do I continue to keep the meat/fish in the middle of the heap each time I turn it? I also have prawn heads and shells and the shells of mud crab. As we are in Autumn now I understand I will need to keep the heap covered with a tarp. Would you advise me if I should use the raw meat and seafood in the heap please

    1. If the compost gets hot enough, like it should, you shouldn’t be able to see any of the meat/fish/scraps in the middle, it should have disappeared! Make sure it’s all cut up very fine so it breaks down faster! Make sure you also have enough of a material rich in nitrogen between all the layers, such as manure, blood & bone or something similar, as grass alone as a nitrogen source might not get hot enough.

  64. I admit that I was sceptical about this method of making compost. I am therefore delighted to report that it worked. I did not worry about having a precise carbon-nitrogen ratio mix: most of my raw material (approx. 3 sqm) was grass clippings, with about two months’ worth of kitchen scraps; some garden refuse (twigs, leaves, weeds, and branches cut into small pieces); and some shredded paper. I followed the instructions almost exactly otherwise, except that occasionally the interval between turning the pile exceeded two days. I also watered the pile after turning it each time.

    The inside of the pile grew exceedingly hot during the composting process, as expected. I doubt that the white substance that appeared (see earlier posts) is actually “fire blight” – but even if it was, it did no harm, and it disappeared in due course. The pile was typically smelly after having been turned each time, but this smell only lasted a few hours (at most), and was attenuated with watering.

    In three weeks, all of the raw materials (except for some twigs, woody roots and bits and pieces of other wooden matter) had turned to compost. The temperature dropped considerably and there was no smell; it was impossible to identify any of the original material. The final stage in the process – from the point where there was still some identifiable grass clippings, leaves and paper, to the point where I only had warm, friable compost – seemed to take place overnight and occurred very late in the process. I noticed only a slight loss of volume overall.

    I began using the final product almost immediately. I screened some of it to use as a turf underlay, and used the remainder – including twigs and other matter, all of which I am told will eventually break down – on various garden beds, most of which have a poor soil base. I have no doubt that my plants will thrive.

    A few points:
    1. The twigs, etc., that do not break down might be profitably re-used in subsequent compost production (ie, if you prefer not to use them on your garden bed).
    2. This video ( demonstrates how the heat generated from a small compost pile was able to heat water for 500 hot showers!
    3. The regular turning of the heap is very good exercise!

    Thankyou for an excellent tutorial.

  65. just read your great article and may apply it a compost heap i have just finished preparing. I am working as a partial teacher here in a district outside of Kathmandu city Nepal. Trying to help the Nepalese people move away from chemical fertilizing back to natural methods. if you know of any permys that want to help out in Nepal send them my address, these people could really use some teachers in this field.
    i definetly will be trying out your method on the next heap i build thanks mate

  66. This is the best How-To I have found yet!
    A big thank-you; I’ll be sending more people your way for sure.

  67. Great site and im keen to try it.

    Is it ok to add moss/grass clippings that have been treated with ferrous sulphate? Had a guy come out to look at our lawn as it had been left to its own devices for over a year (We have just bought the place), It was strimmed back and treated with ferrous sulphate as we had more moss than grass!

    2 weeks after treatment, we are still raking out the moss and old dead grass i was hoping to use this in some way rather than have to burn or dispose of it as there is quite a lot of stuff (1/2 acre of lawn). Would it be more carbon rich than nitrogen given that its mostly dead?

    Would it be suitable to mix the resulting compost with some sand to make a good top dressing for the lawn?

    Cheers Neil

    1. Hi Neil, You can definitely compost the moss and grass, the iron sulphate should be fine, it will simply make an iron-rich compost. If the lawn clippings are mostly dry, they will be richer in carbon, you might need to add a bit of nitrogen rich material to help it break down. You can use the compost straight as a lawn top-dressing, add teh sand only if you need better drainage.


      1. Thanks very much for the reply.

        Im trying to get hold of a shredder for some hedge clippings and brambles so once i have that ill get everything pilled up with some fresh grass clippings and see how it goes.

        Ill report back, from the ever tropical Northern Ireland!

  68. Hi love the hot composting method but i must admit that i wasnt as diligent in turning the pile for about a week after the first ten days we were bombarded with rain for about 4 days so i had my pile covered with a tarp. When I uncovered the pile i saw mushrooms everywhere so i turned the pile and watered it as usual but the next day a mushroom head was poking out. I wanted to know is ths something that I should be concerned about and what could I improve upon to reduce the amount of mushrooms in the pile. I have also heard of mushroom compost so could the sight of mushrooms be a benefit. My name is Joseph just a beginner composter that is looking for some answers.

    1. The mushrooms are just breaking down the carbon-rich materials in the compost heap. You’re making mushroom compost! If mushrooms are growing, it indicates that the heap has cooled down too much, because mushrooms won’t be growing in a hot compost system that is cooking away at 55-65 degrees Celsius!

  69. Hi! Your information is great!! I have some questions… Can I put manures (horse) straight in the compost pile, or do I have to leave it until it dries before adding to the pile? And is it reliabe to use sawdust for the compost?is it possible that it has some chemical products on it?

    1. Yes, you can add horse manure straight to the compost pile, that’s fine, no need to let it dry. You can also use sawdust in your compost, use thin layers, as long as it’s from natural timber.

      Don’t use sawdust from man-made wood products such as particleboard, MDF (medium density fibreboard) or plywood as these contain formaldehyde-based glues which are toxic.

  70. My understanding is that microorganisms are what make a compost pile work, and microorganisms are found in soil. So why don’t you recommend adding soil to the green and brown materials in the compost pile? Thanks.

    1. Hi Bob, in the first step I do mention adding activators such as old compost – this is because compost that is already made is the richest source of composting bacteria.

      You can definitely help things along by adding soil if you have a rich, healthy dark humus soil with lots of organic matter in it that is packed with soil life.

      Unfortunately some soils are quite lifeless, damaged severely and quite sterile. The type of soil really matters.

      If you don’t manage to inoculate your compost pile with premade compost or healthy soil, the ever-present microorganisms still somehow find their way into the compost heap!

  71. Hi Blackthorn,

    I’ve been making compost off and on for years, using various methods, but I don’t think I’ve ever succeeded in making a proper hot compost heap, so I’m now quite excited at having a go at this, having seen the proper way to do it.

    I have a slight worry though. I haven’t seen any mention (I don’t think) of vermin (typically rats), which can often be a problem with cold composting, even using a bin of some sort. I would have thought an open heap would be more prone to vermin, or does the high-temperature keep them at bay?

    With thanks and best wishes,

    Mike (from the UK, where the “summers” seem to have been getting colder and wetter in recent years!).

    1. Hi Mike, at the temperatures of hot composting, any rats or any other vermin that get into the heap when you first build it will be cooked, decomposed and thoroughly composted – you’ll be lucky to find anything but the shiny clean bones!

  72. Hello again, I have now made about a dozen hot compost piles, and never had one fail, winter or summer. I use used pet bedding mixed with whatever green I have, it’s so easy and an amazing process! Excellent site. My question is, I want to heat my polytunnel over this winter with a succession of hot compost heaps, but usually my pile is about 3m cubed, so I want to get this down to about a metre. Is there a way I can make my piles more ‘efficient’ by using different materials so I can get the volume down? Thanks for your help (:

    1. Great to hear your success with hot composting, thanks for sharing! No need to make your compost heap smaller, you can tap into the heat of the bigger pile and direct it to your polytunnel enclosure. If you do a search on the web you’ll find instructions for building hot compost water heaters that can be used for providing hot showers, etc. They just use a long heavy duty hose coiled under the compost heap. Instead of showering with the hot water you can have it circulating through a long copper pipe or a copper coil (which radiates out the heat) inside your polytunnel enclosure, and connects back to the hose as a big loop, like a solar hot water heater.

  73. High Blackthorn, what a great site, I love it.. I’m a long time organic gardener and have cold composted for many years. I have a 2 bay set up where I build up the heap progressively using any waste I can get from the garden and kitchen inter-layered with soil. When the bay is full I move it top to bottom into the 2nd bay, aerating it and moving the oldest compost to the top. I get 3 bay-fulls (about 3 cu.mtrs) of good quality compost a year from the system and I am able to use it continuously as the second bay continues to break down. Its worked well but I really like the sound of the hot composting process and plan to start my first heap. I can get an almost limitless supply of wood chips from the local tip (accumulated waste from arborists), so I was thinking of using this as my carbon content and chicken manure as nitrogen. The woodchips are fairly course and I am wondering if this will work OK. I am using a lot of my organic waste from the kitchen and garden in my wicking worm beds these days, so there is less than there used to be for the compost heap.

  74. Hi John, I really doubt that new coarse wood chips would lend themselves to hot composting as the only carbon source, the bacteria would have trouble accessing the carbon as it’s locked up in the wood and there is not much surface area for the bacteria to act on to start breaking down the material. My guess is that the heap would starve of carbon very quickly.

    Also, making a two ingredient hot compost is something I don’t recommend, the finished product is only as good as the materials you put into it, the more the better for a more balanced compost with a wider range of minerals and nutrients.

    You could re-mulch the wood chips to finer pieces and give it a try, but the end result won’t exactly be a fantastic compost unless you add more ingredients in there.

  75. Many thanks for the feedback. It is appreciated, however I do want to make a couple of points.
    First, I have been using woodchips in my cold compost for years without problems breaking them down, they are crushed in the chipping process which splinters them and increases surface area significantly.
    Second, I have been persuaded recently that the main benefit of compost is that it supplies food for the soil biology. It is said that the diverse microorganism population of the soil breaks it down and provides nutrients to the plant in a form easily assimilated by them.
    Humus is probably the most concentrated form of food suitable for microorganisms, hence my interest in hot composting, but in nature cold composting seems to be the way microorganisms are naturally fed. It seems to me that the origin of the compost is not so important as the micro-organisms attracted by it.
    In my worm farms (built into raised self watering wicking beds) I feed the microorganisms with finely chopped kitchen and garden waste (A large handfull every 2 days). In 4 days the waste has been largely broken down by microorganisms with the help of composting worms. Burrowing worms distribute the microorganisms and their food into the plant growing area of the wicking bed).
    A good article on this and related subjects can be found at:-

    My blog on Wicking Worm Beds is at

    Incidentally, I have used your list of C:N ratios in my blog, I hope you don’t mind.

    1. Hi John, excellent points, thanks for sharing! If the woodchips are not large hard chunks on wood, it’s fine. I use a chipper type mulching machine with a large slow turning cutting wheel and feed heavy tree branches through it, which I then cold compost like yourself.

      You’re welcome to use my list of compost materials C:N ratios, as long as you cite the source, either the site or the page as a link.

      You’ve got some interesting articles on your blog about one of my favourite subjects – worm farms, I’m looking forward to reading them!

  76. Thanks Blackthorn, The link to this page went in well before the C:N list. They are both in my blog on Organic Gardening, and the list is in the article on “Compost” (What else?).
    You can access them through a link in Wicking Worm Beds if you wish. Thanks again for your great blog, and the use of your C:N list. I am sure my blog visitors will get a lot out of them both.

  77. Hi, great article. I am preparing a aerobic compost of mixing with 60% paunch (21:1), 20% wood chips (probably 226:1 or 400:1) and 20% of wood ash (25:1) for commercial purpose in winter season. Today (1st day) I recorded temp is 22C only. Was my mixing ratio wrong? If wrong, how to correct them now? Its open, no cover and rainy. pls advise. Regards, Jakir

    1. Way too much wood ash, that would be very highly alkaline! Wood ash is only meant to be used in small amounts, 1/5 is way too much. Less wood ash, perhaps a greater variety of materials. What exactly is paunch, is that animal offal?

  78. Hi, Thanks. Yes that is cow paunch. since that amount of ash is already in mix, so could I add some paunch to increase temp as temp is still low? I like to achieve a C:N ratio of 30:1. Pls advise accordingly. I did not found any weblink that help to calculate C:N of paunch.

    1. Even though offal is high in nitrogen, it’s strongly bound in proteins, and it’s not very fine in size to have a large surface area. You need a source of nitrogen that is more accessible to bacteria to get the whole thing started, such as manure, or blood and bone, etc. Most often, meat is added to the centre of the heap in a small amount, in the form of road kill, bones with meat still on them etc. In this position, where the heat is most intense, the meat is completely broken down. Wood chips and meat is not a workable recipe for hot composting, it’s a way of composting meat scraps slowly in pits in the ground, which is the way farmers dispose of dead livestock, they dig a pit with a front-end loader, fill it with sawdust, put in the animal carcass, cover it with sawdust, then bury it with soil. The nutrients are returned to the soil slowly that way.

  79. Thanks for the ideas and techniques under discussion. I make a lot of compost, using mainly the neighbours’ lawn clipping plus leaves, wee, chook litter and the odd lucky bag of horse manure. I scored a lot of “aggie pipe’, a ribbed perforated black plastic rigid tube that greatly speeds up composting. I just coil it in the Dalek-shaped compost bins (!) and use generously through the big heap. Compost near the aggie pipe matures sooner, I assume because of the oxygen it provides, and also the housing for worms. I highly recommend introducing aggie pipe through your compost, particularly if you have a bad back, as turning is obviated and moving the mature compost is easier when you extract these air tubes.

    1. Thanks Marion, that’s a fantastic tip, really love it, simple and effective, I’ve got to try that in my compost bins!

      1. That’s a great tip Marion. I have heard that compost aerators, which are usually a pipe positioned vertically in the centre of the compost, will cool the pile down. Does your method avoid this?

      2. I’m guessing it wouldn’t cool the pile down because the centre cab still retail heat, while the air passes around the sides.

  80. Great read! I have been a cold composter for years but I am how moving into hot in order to try to heat water for a shower! I have read other sites about the process but I am still curIous on how to attain the “hot” decomposition but have my system last for longer than 18 days. Also I am working in the tropics of Thailand if anyone has any recommendations for systems or adaptations. Cheers!

  81. Thank you very much for such an enlightening explanation on how to hot compost. I want to let you know that I have a successful result from following your instructions. Although the size of my pile never quite reach 1.5 as required, still the core temperature heated up to around 150-160 F. The pile consisted of straw, dried uncomposted leaves from fall season, grass clippings from lawn, donkey & goat manure ( from a friend), garden weeds, kitchen waste. I used pee & some old garden compost to activate it. I am harvesting the compost today, it looks like a rich, dark brown heap.

    1. Excellent results, and good to see that you’ve used a nice mix of materials too! Well done!

  82. I need to know the c:n ratio for fronds from palm oil trees, is it similar to coco palm trees? So far I only get different conflicting figures. Apperciate the help.
    From Jen in Malaysia.

    1. If they palm fronds that naturally fall to the ground, they would be dry, no green colour in them, they will be mainly carbon.

  83. Ok, noted and thanks. Have used your technique for past 6 months using different carbon sources and vareity of palm oil fronds. We add compost activator, liquified 20 litres to every heap. Compost activator has anti oudour and EM additive to it. For each heap, the finished dry weight is approx 870kgs. We are doing 6 batches per day for use in our 2,100 acre plot of oil palm, young and old trees. No chemical fertiliser as far as possible since plantation is beside national park reserve.
    How do we post you pictures of our production using your method?
    You have contributed a lot to us in terms of knowledge and tech support.

  84. Hi there, can you please explain if the compost got too hot and you get “fire blight” mould, does that harm the compost to be used when it’s ready, or do I have to discard the whole heap of compost?


    1. If the temperatures over 65 degrees Celsius you get fire blight which is an anaerobic bacteria, to remedy add some carbon rich materials and turn the compost to get more air into it to and cool it down. Then continue turning as per the procedure.

  85. Since the 90s I’ve used a modified Berkeley method that virtually eliminates turning more than one time.

    With a ground base of 1/2 inch diameter brush, cut to 8-12 inch lengths approximately 6 to 8 inches thick, I made a series of alternating layers of first high carbon about 2-4 inches, topped with 1-2 inches of high nitrogen material, or add ammonium sulphate or urea sprinkled on.

    Repeating this to the 3 foot high point, I add another 2-4 inches of short brush and then more C and N layers up to 6 feet high. In higher levels I mix the brush into the “C” layer. The turning is eliminated since air easily flows through the pile from the heat.

    To slow the air flow I top the pile with soil or fine compost material. When finished building the pile I soak it well with water, and tromp it down if the material is to “fluffy.”

    This produces top grade soil in two to three weeks.

    For the outer material that does not get hot I simply screen it out and add to the next pile build. I’ve produced hundreds of Cubic yards of very fertile soil this way. It sells for top dollar, and makes a garden like you need to see to believe.

    Plants growing in this soil are disease and parasite bug resistant and I use zero pesticides, and zero fertilizer for lush, large plants and vegetable yields.

      1. Hi BrisMatt, I’ve edited the previous reader’s comment for clarity, it now reads “1/2 inch diameter brush, cut to 8-12 inch lengths ” – that single comma makes all the difference. As you’ve seen, I’ve also edited your comment to keep the discussion public!

      2. Hi Angelo, Thank you for editing. However I still don’t know what the brush looks like. It still doesn’t make sense to me. WRT to the email address, I have used a disposable one whereby I can delete that address once I get a reply from ClaudeA.

      3. Hi BrisMatt, ‘brush’ is just another word for ‘brushwood’, basically it’s just wood of twigs and branches that have been cut or broken off. Hope this helps!

    1. Hi Claude, sounds like an interesting approach to composting, but how do you separate the cold composted outside material that will still have active weed seeds in it from the hot composted interior compost where any weed seeds would be deactivated?

      I should point out that the purpose of turning the compost is not only to get air unto the mix, but to turn every part through the hot core of the heap to break everything down – pathogens, weed seeds, etc.

      Thanks for the great suggestion!

    2. Hello Claude, I’m really interested in this method of yours. If you dont mind, can you also send me some pix like what you did for BrisMatt?

      I did hot composting some time ago but gave up just because I cant turn it regularly. I am a full time worker and by the time I get home I have very little time and energy to spare for turning the compost. This method of yours would really help me a lot. Thanks.

  86. Thank you, Angelo!

    Being a farm boy, my concept of “weeds” from having generations of family and settings’ experience, is based on the fact that nothing is an unwanted plant – every plant has a beneficial part of the production.

    In fact, I purposefully grow “weeds” just for the soil-production process. Jerusalem Artichoke is a noxious “weed” in my gardens, and yet I allow it to grow and multiply wild to use its awesome heavy stalk for part of the branch material in the compost pile.

    Every “weed” is welcome to grow and thrive wherever it is not a nuisance, and when it is, or I am ready to build a compost pile, I have a ready supply on material.

    I say “every weed,” so I do need to clarify. The only weed I try vainly to eradicate here is clinging burr. But, like all others, it manages to sprout all over from wind, bird and animal tracking, so i simply add all i pull to the compost.

    Please re-read my pile-build procedure, Angelo, The outside material is separated out to go into the next pile. I use a horse stable, ten-tine fork, and for larger screening, I have an old wire and spring bed frame that screens out brush and un-digested larger particulates.

    If some “weed” seed makes it through, the 100% compost soil of my garden is so giving I merely pull the “weed” out, roots and all with a little tug.

    The moisture trapping and awesome nutrient content of the soil produces very heavy yields, and plants grow very late in the season, I pick raspberries to just past frost, and root vegetables keep in the soil all Winter, The rhubarb, mints, parsleys, perennial herbs, garlics, onions, and other biennial and perennial plants thrive here in the Puget Sound winters, and I pick Siberian Kale every month except for those with most days below freezing.

    Artichoke grows to seven feet, and each stalk yields up to six hand-sized globes. I sow garlic like one sows a lawn, and the large bulbs crowd each other but with adequate water, the yield is amazing.

    Dahlia loves this soil, and since “weeding”: is so easy, they grow without any competition to very large proportion. Ditto Glads and lilies.

    The point I’m making is that “weeds” are merely a mental issue, and once their management is put into proper order, become a very beneficial ingredient to a wonderful garden!

  87. Britt, I sent the following to your eMail – Thanks Angelo!:-))

    I’m happy to share pix with you!

    I’ve been meaning to create a bog page with this method, but until this interest here in, no one seemed to take notice!

    I have numerous pix of various stages of building piles, but it will take some doing to reform them suitable for the blog.

    To use a few words meantime, picture tree and bush branch trimming piles where branch limbs are under 1″ in diameter extending on out to the smallest stems and leaves. Cut these into 8 to 12″ lengths with all forked sections cut to the main stem, to make separation from the fi8nished compost easier.

    Use this material for the ground layer, and the mid-pile layer, and I add some in finer materials that tend to clump together in thick wads.

    The idea is merely to get and keep air flow in the pile, but not too much air, as it will dry the pile and halt the reaction.

    The frequent pile-turning is VERY labor-intensive, and the brush adds air to the pile without the turning. It’s that simple.

    As for destroying pathogens, one or two days at 140 – 160 degrees Fahrenheit destroys such things as chicken bones, small meat scraps, all finer plant material, and begins attacking the lignin component in woody material. The main source of destroying pathogens is not heat, though. The enzymes and living organisms in the hot compost pile – remember, oxygen is the worst enemy of all pathogens – attack the pathogens with vicious ferocity. Think of a bread mold on steroids.

    Again, “weeds” are never an unwelcome part of gardening – every single plant adds a harmonious part to the symphony we gardeners enjoy – nutritious, bug and disease-free, ORGANIC produce!

  88. Hi Claude, I agree with you about the weeds, every plant has a purpose! For us urban gardeners with smaller gardens, sometimes we don’t want an entire garden of lemon balm, hence why I like to use methods that take out unwanted seeds!

    Some pathogens, which cannot tolerate high temperatures, are destroyed by heat, they are literally cooked, and yes, the complex compost chemistry does the rest, lots of enzymatic activity breaks everything down, it’s wonderful stuff.

    Just curious, using your technique, which is a kind of hybrid hot & cold composting system, does your compost pile reduce in size or volume?

  89. thanks for your great work . your effort is awesome
    my question is :
    can i depend entirely on the material of hot compost to fertilize my farm ?

    or , i will need some additives like :
    -chemicals 🙁 ammonium sulphate , super phosphate , ……)
    -micro & macro elements
    -bio vaccines “anti-fungal”

    thanks again

    1. Hi Mike, if you use a good variety of ingredients in your compost, it will be more than adequate, considering that’s how trees have naturally grown for the last 370 million years, from composted material on the forest floor, you shouldn’t need to add anything else, especially not chemicals.

      If you add chemicals to your compost you’ll most likely mess it up because the chemical fertilizers are simply salts in high concentrations and they kill the microorganisms that make composting possible.

      If you need to add a range of micro-nutrients and trace elements to your soil or compost, add rock dust (such as granite dust from rock crushers) or seaweed extract (or just seaweed itself).

  90. Hello Angelo or anyone else who can help…

    I followed this hot composting method a couple of weeks ago, but the composting process has not completed and I’m wondering where I went wrong.

    I built the pile about 1.5 metres high in a cone shape in a spot that gets a few hours sun (this is at the end of winter in Melbourne, Australia). I used two thirds by volume dry brown materials, and one third green materials. The brown stuff was a mixture of dry leaves, pine needles, some partly decomposed fine wood chips/shavings (left after grinding a tree stump) and some newspaper scrunched into balls. The green materials were grass clippings, chopped up garden waste, some kitchen scraps and commercially packaged animal manure (mostly sheep but also some cow and poultry). To get it going I used some urine, liquid seaweed and mollasses.

    I kept the pile moist and loosely covered with black plastic, and diligently turned it every two to two and half days, rebuilding the pile from the outside in.

    It started off well – the material changed colour to a dark brown after it had been inside the middle of the heap and starting decomposing, and there was no smell. I didn’t have a thermometer but it seemed pretty hot in the middle initially (eg. after about day 6 it was too hot to put my arm inside the middle). It seemed to be on track until about 13 to 15 days in, when it cooled down but the material was yet to fully compost.

    That was about 10 days ago. The heap is now dark brown and coarse in texture, and the individual components are still visible (eg leaves) and the process appears to have stopped. I tested the pH and it’s slightly acidic (6 to 6.5). There are no worms to be seen as yet.

    I told my partner the problem was that he wouldn’t oblige with the urine and I had to do it myself with a container, but I don’t think that’s it.

    I’m unsure (a) what went wrong (b) what to do from here. I need a whole lot of compost to improve my clay soil, which is poorly structured and low in humus. I’m planning to put in acid-loving plants.

    Given this, I am not overly fussed about the coarse texture, but worried that if I use the partly decomposed compost it will draw nitrogen out of the soil.

    Should I use it and hope for the best, or try to get it going again with more nitrogenous material?

    Any thoughts or advice would be much appreciated!

    1. Hi Sara, it sounds like your compost started off well, but cooled down too early. If the carbon source materials such as leaves are still visible, it would suggest that the compost heap ran out of nitrogen. I would try to get it going again with more nitrogenous material, you can try using ‘blood & bone’ fertilizer along with whatever other nitrogen source you’ll be adding, it’s extremely high in nitrogen. Also, try to make the shape a bit flatter, like a big cube or cylinder, a cone geometrically has the greatest surface area for the least volume, so you end up with too much material exposed and not breaking down. Hope this helps. Give it a go and please tell us how you go.

    2. Most common problem with Compost failures is moisture. Either too much or too little.
      Because it went well to start with, i believe again its water. Because the stack got hot steamed and ran out of water.

  91. Sara,

    One thing my French double-turn soil amendment grandfather practiced for his 20″ deep garden soil fertility was direct incorporation – turning in raw, uncomposted material to allow the soil’s natural decomposing agents to assimilate the material.

    One direct benefit of this is the increase in earth worms feeding on the decomposing material. Where plants are growing in the soil the worms’ wastes are directly captured by the roots, and the health of those plants is exceptional

    However, for clayey soil the critical issue is air-flow into the soil. To assure that directly turned-in material gets air, add woody, stemy branchlets that are mainly vertical in the soil and one end is near the surface.

    The immediate results is that the soil can sustain some plants, and the long range effect is great, fertile soil in a year or tww, where material is added several times and the soil is naturally turned.

    Farmers of staiky plants, lie corn, use this same principle to keep the field soils; organic content up, and maintain disease-free crops.

    I have driven the machinery that buries such material – quite an impressive operation!:-))

    Now, as for “brown” material that still has the original shape and some of the texture before hot composting, you will discover that this material is actually completely decomposed except for some of the ligins that hold the woody parts together. It is ready to support most all plant roots in this stage, especially when directly turned into the soil. In a year or two it will be finished in breakdown due to soil-borne activities, such as earth worms, fungus and molds, and the myriad of tiny creatures feeding on it.

    Hope this experience helps.

  92. Hi there, I like to make hot compost (aerobically) commercially for a large volume, using cow paunch (30:1), wood chips (400:1), wood ash (25:1) and chicken manure (12:1). Pls advise me what would be the ratio of ingredients? Very much appreciated.

    1. If you know the % of water in each of the materials, you can use the Cornell Waste Management Institute’s – “Calculate C/N Ratio For Three Materials” online calculator at

      I wouldn’t use too much wood ash, it’s highly alkaline!

      If you haven’t got all the figures to do the precise mathematics, just stick to the basic formula for working with volume, to simplify things, aim to use 1/3 green/nitrogen containing materials and 2/3 dry carbon materials.

      In other words, one part of nitrogenous material to two parts of dry carboniferous material.

      In your case, I would try 1 part cow paunch, 1 part chicken manure and 4 parts wood chips. Use only small amounts of wood ash.

      Since you only have one main carbon source, the wood chips, the ratios to use also depends on how much of the each of the nitrogenous ingredient (the cow paunch and chicken manure) that you have.

      Try these basic ratios on a smaller scale and adjust ratios depending on your availability of materials, and results in composting. If the composting process shows it has too much nitrogen, increase the amounts of wood chips. If it is not getting hot enough or breaking down completely, add your nitrogenous ingredients.

      Keep in mind that there is so much variation in the amount of carbon and nitrogen in any one ingredient sourced from different places or even different times, that you can’t calculate this exactly mathematically from the first instance. It’s a matter of experimenting.

      Also with your large scale hot composting, will it be in a huge commercial closed vessel or composted on the ground in open air – this will determine how much cow paunch you can use. In open space, outside of an enclosed commercial scale hot composting vessel, you can’t have animal guts exposed to open air, you can only have smaller amounts in the centre of your compost pile when you begin, deeply buried in the core of your compost where it gets the hottest. The size and density of the woodchips will also determine how much paunch you can use, and how effective your carbon source will be. Large chunks of heavy, dense wood will not compost very easily.

      My advice, test your ingredients and fine tune the proportions of each material with a smaller heap, then scale up after you can successfully hot compost on a smaller scale.

  93. Super responsE!:-))

    Depending on your budget, and with that scale of material it appears substantial, you may want to look into forced draft composting if for no other reason than to lessen the very strong likelihood that with those very fine particulate materials, and especially the entrails, oxygen flow to the innards of any pile will be severely curtailed.

    Commercial forced draft composters also speed the production by several magnitudes of scale, producing finished soil in less than two weeks, and for many dairies, in one week or just days. Of course, moisture and temperature are critical factors, as combustion temperature can be reached in a matter of hours.

    I’d like to hear of your experiments! Sounds quite interesting.

  94. Great info thank you very much, however, I do have a question regarding the ‘fire blight” comment. When you say “fire blight” do you mean bacterium Erwinia amylovora?
    Thank you.

    1. No, it’s not the ‘fire blight’ pathogen Erwinia amylovora that affects apple and pear trees, you can actually use hot composting to destroy plant material infected with the pathogen Erwinia amylovora.

      I think what is being referred to as ‘fire blight’ in reference to hot composting is some kind of thermophilic composting bacteria.

  95. I am using a 200 litre compost bin rather than an open pile and am only able to get the temperature up to 37C. I would like some help to get more heat.

    I am mixing up the C and N fairly well but maybe I have not enough C because the level of the compost keeps dropping a few inches a day.

    Other thoughts I had were:
    1) The first items I put in were not cut into very small pieces so maybe are rotting slowly. I am now chopping everything up as much as possible. Could the early larger pieces explain the low temperature?
    2) The bin is 90cm high and the circular shape is 70cm in diameter ie much smaller dimensions than the article recommends. Do you think that this smaller capacity explains the temperature not getting any higher?
    3) Turning the content of the bin is not easy. I am mixing it up as best I can, but can’t get to the bottom 30 m very easily. Should I consider emptying out by tipping the bin over and put the compost back more evenly mixed.
    4) I am continuing to add materials (both household peelings etc and garden clippings – I am in Wales so am doing the start of autumn clearing of the allotment); do you think the adding of new materials is slowing the whole rotting process? If so, should I start a new compost heap (or buy another bin) and leave the first one to do it’s own thing (turning when needed)?

    Many thanks for the helpful article. Definitely got the compost bug!! Even added some urine this morning.

    1. The reason why the instruction specify that the compost pile needs to be of one cubic metre in size or larger (over 1000L) is because you need that much material to reliably reach the required temperatures. We’ve all heard about haystacks catching fire when they start composting, very large amounts of material can generate a lot of heat! A small compost bin, even a large one, simply cannot hold enough material to make a compost heap big enough that will hot compost. I have several compost bins, four 200L bins and a 400L bin for cold composting, and no matter what material I use or how much I fill them, they cannot hot compost.

  96. Not sure why you use a bin, but it may be due to occlusion of air. Also, the finer the source material, the less trapped air – oxygen – there is. You might look into cold composting with a fungus mix for your operation. The fungus destroys all material – seed, bacteria, and lignins, much like hot composting.

    Also, if there is enough air-oxygen, and the nitrogen is low, add a little ammonium sulphate of urea, or even blood meal to raise the “N.”

    Also, fall leaves clump together in mats that block air flow, and exclude air entrapment. This is one main reason I developed the addition of brushy material and the smaller limbs and branches to allow for air flow. On a cool morning with the sunlight right, one sees a wispy steam rising from the top of a good hot pile with an earth or finished compost topping to partially seal the pile.

    Works every time for me.

    Thanks to Angelo, this forum promotes one of the nicest composting informations sites online – so, thank you, Angelo!:-))

    1. Thanks Claude for bringing up another method of breaking material down like hot composting, but with a cold composting system.

      You can cold compost weeds in an airtight sealed container using the bokashi bin mix, this is a mix of lactobacilli, fungi/yeast, and phototropic bacilli (Lactobacillus casei, Lactobacillus planarum, Lactobacillus fermentum, Lactobacillus delbrueckii, Bacillus subtilis, Rhodopseudomonas palustris, Saccharomyces cervisiae) which is used to ferment food scraps. The fermentation process is very acidic and destroys weeds and weed seed. After two weeks the fermented waste can be added to the compost bin or buried in the soil.

      I even found a great technique at the GARDENS FROM GARBAGE website FAQ ( which describes how to make soil with fermented bokashi material:

      You can make your own “soil factory” in a storage tub: put some good soil on the bottom, add a layer of well-drained fermented food waste, mix well. Cover with a layer of soil and flatten. Cover with plastic or a lid to keep it from getting wet. After about 30 days, it’s ready for use as “good dirt“.

      I’ve got to try this myself!

  97. I donate about a day per week to make soil for a community garden in Seattle. The other day one gardener showed me his new experiment with this His hopes were for kitchen wastes, and meat-bone scraps.

    I’m not sure how much pathogen reduction earth worm vermiculture does, but I would think that the soil these little creatures produce is full of similar fungi and bacteria. Pathogens are viciously attacked by oxygen-breathing organisms, and worms promote oxygen breathing flora and fauna, so vermiculture may be a viable procedure to produce safer material to add to the hot pile, or maybe use as is, which I know many do.

    I’d like to learn about more ways to produce soil from different raw feed stocks. Each has specific nutrients that combine to provide plants with both health and disease / parasite resistance.

    In my use of 100% compost for the garden growing medium, I see very little parasite and almost no disease, opposed to plants growing in the native soil. But I have not made an effort to determine what causes this.

    I do have some slug issues, but the rough texture of the compost turns most away, and for the persistent ones I scatter diatomaceous earth around the few plants slugs insist on messing with. They do not cross the DE at all, and where it is on the plants they also stay off there.

  98. Has anyone here experienced composting plywood, or other similar glued-together wood construction material? I was given quite a bit of thin plywood which is separating at the glue joint.

    After reducing the size to about 12″ square or smaller, I have built a pile in layers of recent yard wastes – acorns, leaves and some composted leaves of last year, cardboard and paper, and hot material from the active compost pile.

    With a few pails of water added to these layers and topped with active, hot compost, I’m hoping the Douglas Fir plywood will decompose by next Spring. I wonder if I should have added a commercial form of nitrogen, such as urea or ammonium sulphate to help the large amount of wood to break down.

    If anyone has experience with similar material your advice is appreciated. Also, Angelo, did you see any mention of the fungus being used for woody material breakdown? I’ve seen piles of wood chips where fungus permeated the pile and rendered the wood into a softened form, but not into a completed soil-quality material.


    1. Hi Claude,

      There have been studies on composting of plywood.

      Wiltcher, D.,, “Composting of Phenolic-bonded Softwood Plywood Waste”, Forest Products Journal, Vol. 50, No. 10, October 2000

      Leungprasert, S. and L. Otten, “Fate of Formaldehyde in MDF Sawdust during MSW Composting”, University of Guelph, Guelph Ontario

      The glue in plywood is urea-formaldehyde glue, which is toxic on account of the formaldehyde it contains. From the studies it looks like it takes 180 days (i.e. half a year) for the majority of the formaldehyde to break down in the first study. In the second study, 90% of the formaldehyde is broken down after 10 days of hot composting. It appears that it’s not completely broken down and considering formaldehyde is a known carcinogen, I would simply find less toxic materials to grow food with! Its not worth poisoning your soil for, considxering carbon based materials are everywhere, autumn leaves, fallen branches, newspapers, etc.

      Fungi break down wood into soil, that’s their role in Nature, you can use shitake mushrooms to turn hardwood logs into lots of mushrooms and mushroom compost.

  99. “Need optimum temperature of 55-65 degrees Celsius. At temperatures over 65 degrees Celsius a white mould spreads through the compost, which is actuallyfire blight, an anaerobic bacteria. Temperature peaks at 6-8 days and gradually cools down by day 18.”
    Hello there from South Australia, I have made a pile at our school, it has been cooking for 7 days now and when tested today and the day before it was 75 degrees and today probably about 65.I had not measure the temp before this. Can it get too hot? And this white mould, is that a good thing or a bad thing. It has lots in the middle of the pile. I assume if I turn the pile now…it will heat up again and that is what you want? I have been told just to leave it. Perhaps add a little more water? It has a mix of roo poo, straw, blood and bone, lawn clippings and Lucerne hay. It gets incredibly hot, great to show the kids at school! Would appreciate advice, thankyou.

    1. Hi Janelle, your hot compost is getting too hot! If it gets way too hot some of the bacteria that are more comfortable living at the lower temperature ranges get killed off I believe. Only add water if it needs it to maintain the correct moisture level. Please keep following the instructions, it’s still on track, keep turning it every second day, it will help cool it down, and you should have perfect hot compost by day 18. Please let us know how it goes!

  100. Hi, I followed your hot composting instructions but the heap has cooled down now and is just warm. I can’t find blood and bone, I only could find blood pellets and these have not made any difference. Is there any other other quick fix to warm it up? It was going so well, it is covered as the weather is cold here in France. Best regards Katharine

    1. Hi Katherine, you can add ANY rich nitrogen source to make the compost heap heat up again. Any animal manure will do just fine, as will human urine!

  101. Hi there
    Firstly this is an amazing source of information and inspiration, thank you.
    Secondly I am a total novice and have just started my first compost site. I am also awful when it comes to maths. So I was hoping you could help me.

    I have an abundance of the following;
    Rabbit poo and wee, mixed with sawdust.
    Chicken poo
    Grass cuttings
    Used organic compost (used for last seasons veg growing)
    Kitchen waste
    Butterfly bush trimming
    Willow trimmings
    Fallen leaves

    I can also access horse manure easily.

    Would you be able to give me a rough ratio in percentages? Hope that made sense!.

    Again, thank you so much for building this resource. I used to be a secondary teacher and from this point of view you are excellent at communicating information that is accessible to a wide range of abilities.

    Kind Regards


    1. Hi Claire, thanks for the nice feedback, you’re welcome!

      It’s quite simple – forget the maths, just use the simple formula of 1/3 nitrogenous materials (manure, greens, kitchen scraps) and 2/3 dry carbon materials (old leaves, etc.)

      Remember, we’re aiming for a C:N (carbon:nitrogen) ratio of approximately 25-30:1.

      Your garden waste (30:1), green wood (25:1) and vegetable scraps (25:1) you mention are already at the right ratio on their own! To make these heat up nice and fast, add chicken manure to these ingredients.

      Grass clippings (20:1) which are high in nitrogen need some material high in carbon such as dry leaves (60:1), so mix 1 bucket of grass clippings with two buckets of leaves.

      The Rabbit poo and wee, mixed with sawdust is already a blend of nitrogen and carbon rich materials, that’s pretty balanced. If there’s too much sawdust in there, add some of your chicken manure to it to increase the nitrogen content.

      That covers all your materials, that should do it!

  102. Hi Blackthorn.
    I have started trying out a hot compost heap & have a couple of questions. I have had to create the pile over a cple wks (the space for the pile is about a metre square) due to having the correct materials ready. Will this have made a massive difference and will it still be able together hot. measured the temp 2 days ago it was 30, I then added more layers the next day measured temp again and it was at 40 degrees. It is about 700 cm high now so still going..
    With layering, should my carbon (dry layers) be thicker than my nitrogen (green) layers to get the correct carbon: nitrogen ratio or the other way round. Also how thick should my layers be?
    Seems to be taking me a lot longer than an hour to create a heap, although I don’t have a shredder so doing it all by hand…
    I live in the UK so getting colder here now, I was going to cover with tarpaulin,..should I do this on all sides or is the top and front enough?
    Appreciate the help, it is a very exciting process.

  103. Hi Blackthorn

    Thanks for the informative site. I would like to share my hot composting experiences with you, although I use a different system that takes a bit longer than 18 days and requires no turning. I live in a very windy part of South Africa, so I’ve made a 1m square chicken wire support and lined the sides (but not the bottom) with heavy-duty black builder’s plastic.

    I put garden waste and food scraps into this over a period of a few weeks, adding woody material from a previous compost heap and keeping it moist. I don’t have any manure but I have plenty of leaves, grass cuttings, hedge trimmings and weeds. I usually cut the stalks and big pieces up with pruning shears before adding. I cover it loosely with plastic while the heap is growing and it generates some heat.

    When it is full (about 90cm high) I add a thick 30cm layer of grass cuttings mixed with dry leaves, water it well and cover it tightly with black plastic weighed down with stones. It gets extremely hot and gives off steam if I lift the cover and dig down with a trowel. After a matter of days or a few weeks it cools down and turns into good black compost all the way through. The earthworms multiply the longer I leave it.

    The time taken varies, depending on the season (we have cold wet winters and hot dry summers – I will time it more exactly in future). I used to turn it occasionally but it didn’t seem to speed things up much, and I’m nearing 70, so it’s a good method for an energetic geriatric. I live in a complex built on clay, so this is a valuable resource for my patch of garden and the others I look after.

    Do you think this would work on other continents?

    Best wishes, Jackie

    1. Jackie, i’m really glad you shared that. I’m in Ohio at about 41 degrees North, so we experience all four seasons (snow in winter). I will let you know if I try it, but i think it would work in summer.

  104. hi , i am in india and think your explanations are very have taken a lot of effort. can you please answer one question. after we have made the pile and turned it ,can i water it again if i feel it is too dry.will appreciate an answer.. thank you ..

  105. Hi, I had been trying to get my compost to heat up for a couple of months and was getting a bit demoralized. I totally underestimated the amount of nitrogen that I needed to add – or maybe I didn’t realize how much carbon material I had put into the piles.

    Anyway, a week ago I added a bag of Blood and Bone (about 5kg) into each compost pile and Voila! Worked like magic.I can’t tell you how excited I was to see the steam pouring off of the piles.

    Thanks very much – this is a fantastic website.


  106. I am Irish and live in Poland. At this moment, I have about 8 large piles of horse bedding that I have been composting since around april. The latest pile is about 2 or 3 cubic metres in volume. I wont turn it because it is a lot of work although I do check it to see if it is hot. Occasionally, I have removed some material from the bottom outer section and even that has been hot. I intend to use the composted material for raised beds. I havent used tarps nor any sheets to retain heat etc but I have used soil. I dug a trench around some of the compost heaps to a spades depth and width and used that soil to form a layer coating on the heaps. It isnt a perfect cover but 80 percentish. Recently, I tried to use a cover comprising of some hay and dried garden grass etc that had been forgotten nearby a ditch and it seems to work. It can help to retain moisture. On some heaps the soil is black but on others the soil is just like greyish soil. Hopefully, I will have about 5 or 6 cubic metres when it is ready to use by september – october.

  107. Hello everyone!

    Thanks for this really interesting blog and summary.
    I am working for the IUCN as a Marine Biologist on a Resort in Maldives. The situation with the organic waste is quite sad: Every resort and every local island is throwing the entire organic waste into the ocean, which is detrimental for coral reefs. I am looking for a project that eventually also has financial support to find a solution for this. Herein I am looking for opinions, specialists and ideas. The conditions are a bit difficult: high amounts of different organic waste (raw material as well as cooked left overs) (about 500-1000 kg a day), tropical conditions, great limitation of space, smell needs to be minimized. i am looking for a way to turn it into soil rather than bio-gas, because also soil is limited in Maldives. Eventually every resort and local island could start producing a small amount of vegetables and fruits if we would find the right solution.
    I am wondering if you would be interested to do some consultation for me or if you have any further contacts that could help me further in this matter.

    Thank you, Barbara

  108. Hi, I’m using composing materials e.g; cow paunch (C:N 21:1), Chicken poo (C:N 15:1) and Wood ash (C:N 15:1) to make compost (aerobic, uncovered) commercially in this winter (also raining) in NZ and the proportion ratio was 70% : 15%: 15%, respectively. 4 weeks gone but temperature still low (34C). It ran well in the summer, not in winter. pls advise how to increase heat inside the pile (1.5m high) or any related advise? Thanks in advance

  109. Hello,

    I am trying to have a pile of compost for heat. I will be using straw, wood chips, vegtables matter, grass , and urine. My goal is to have a hot pile for as long as possible. So I am asking how long can I keep a pile going at the best possible heat. I am going to try heating my house using water transfer to radistors, for a 6 months. Will I need 2 piles three months each? What will be the best mix. And are these ratios by weight or volume? I would ghuess weight. But I want to hear it said. Thanks , please e-mail me

    1. Making compost is one thing, building a compost powered hot water system is another, and that would be another whole article in itself! If you do an internet search on “hot compost showers” there are a few videos and articles that may be helpful. For a long, slow release of heat that lasts for months it appears that some people have used very large scale anaerobic systems which produce very poor compost because they use only wood chips rather than fast heating aerobic systems like this which use a variety of ingredients and produce a very rich compost.

  110. i have been trying hot composting but something doesnt feel rite. its been over a month but the compost pile is still hot around 140F. The color has changed to blackish brown and smells sweet n earthy. I used sugar cane trash, rapseed trash and banana leaves as carbon source and for nitrogen i used food scraps and cow manure. C:N ration is around 30.1 and i always keep the pile covered with plastic. where am i going wrong? help would be appreciated.

  111. I just have a quick question about manure in a hot compost bin; should the manure be well rotted to start with or fresh? Thanks in advance!

      1. I am now on day 9 of my hot composting but the pile has significantly cooled. When I turned the pile yesterday it was warm and steaming a little in the centre but it wasn’t hot. How do I get it back up to temperature?


      2. As mentioned in the article, if it starts to cool down, you can heat up the compost by adding a handful of blood & bone fertiliser per pitchfork when turning. You can add ANY rich nitrogen source to make the compost heap heat up again. Any animal manure will work.

    1. See the instructions listed under Day 4 – “Ensure that moisture stays constant. Put gloves on and squeeze a handful of the compost materials, should only release one drop of water, or almost drips a drop.”

  112. Hi there,
    I’m trying to compost just flowers here in my locality. Here in India we have lots of temples and a lots of flowers are offered there , even some temples generate 10-20 ton every day, and they simply throw it. I’m planning to make compost and colors out of it.
    Can you tell what I have to do when I’ll be only composting flowers like Marigold, rose, etc.
    And how will I manage the composting ‘coz I’ll be getting 10-20 tonnes of flowers daily!
    Suggestions are appreciated 🙂

    1. The flowers have the same C:N ratio as ‘garden waste’ and ‘weeds’ listed in the article, with a ratio around 30:1.
      Add a little dry material rich in carbon and you’ll be able to compost it.

  113. Hi just finished my first compost pile and have a lot more material for another one. Can you please tell me how much comfrey should I put in the middle of the pile? I also added vegetable scraps near the middle of the pole as well.

    I watered the pile once I finished and am a bit anxious that it may not have soaked through the whole pile – water was running out the bottom but I have used leaves that where on my driveway and some had started rotting already (very long driveway). Should I keep watering the pile each day? I am on day 1 of the 18 day composting system.

  114. Hi Angelo, thanks for your very informative website 🙂

    I’ve never had much luck with hot composting, but my recent attempt (following your instructions) got me closer to success than I had before. Like Sara who commented above, I think this time around I had an issue with the compost heap cooling too soon, possibly because the carbon sources (including broken up twigs & woody vines, as well as some newspaper/cardboard) were too large or too imbalanced to the nitrogen that I added (including chook manure, kitchen scraps, fresh grass clippings). It’s been over 18 days but the carbon rich materials still haven’t broken down, the temperature has dropped and a few worms have been moving into the heap.

    I’m itching to get this compost into the garden asap so I can get my summer veggies growing, so was hoping for some advice. Do you think it would be better for me to mix a nitrogen rich source (i.e. chicken manure) into the heap and keep it going for another week or so, or do you think it’d be possible to apply the half-broken down (still quite woody) compost along with additional chook manure directly to the garden beds now? The latter option appeals to my impatience, but I’m worried that nitrogen draw down might slow the growth of my summer seedlings. Would you recommend that I be patient and continue the composting above ground, or can I get away with digging it in now?


    1. You’re welcome!

      The best way to make any compost is to break up your materials really well. Large chunks of carbon-rich material don’t break down very easily, there is very little surface area for the bacteria to act on. By breaking up materials you increase their surface area which exposes more material for the bacteria to work on.

      If you add compost with woody material that is not broken down into your soil, the woody material will continue to break down in your soil, but the bacteria will need to draw the nitrogen out of your soil to compost it, which means your plants won’t get to take up the nitrogen, and suffer from nitrogen deficiency. This phenomenon is called ‘nitrogen draw-down’. Don’t do it, you’ll starve your plants of nitrogen and they won’t grow very well!

      Your best option is to use the material again, doing another 18 day hot compost by adding more nitrogen containing material. The idea of using it your incomplete compost as is with lots of woody material in it with chicken manure is not a worthwhile choice because whenever you add chicken manure to your soil you need to wait for a minimum of a week, preferably two weeks, before you planting in the soil, as you can burn the roots of plants and seedlings, and it takes the bacteria time to start acting on the manure to break it down so the nutrients become available to the plant. Plants can’t feed on manure, they feed on the nutrients released from manure by bacteria. Either wait 14 days and still have a problem because the woody material in your soil that won’t all break down, or do another 18 day compost. It’s worth the extra 4 days!

      If you’re really feeling lazy, just get a yourself soil sieve, or make one out of wire mesh, and sift your compost to separate all the course material out. Use the fine compost that has broken down in your garden, and put all the coarse material that has not broken down to one side, break it up much finer, and use it in your next compost attempt.

      Hope this helps!

  115. Hi Angelo and Em

    My own further observations on the hot compost heap that cools too soon:

    Following Angelo’s advice about my similar problem and some trial and error, I’ve found that I need a slightly higher proportion of nitrogenous materials to keep the heap hot and complete the process in three to four weeks. (Perhaps this is because some of the carbon-containing materials I’m composting are at the higher end of the C:N ratio). I re-activated my heap that cooled too soon with more manure and lawn clippings, and some blood and bone, and ended up with a fine, high quality compost at the end.

    Over a number of heaps, I’ve found that adding a good portion of fresh manure (rather than the dry, powdery, more “composted” stuff) makes a huge difference to the success of the process for me. (I’ve been using fresh sheep manure). In my most recent heap, I used fine, more composted commercially bagged chicken manure and it didn’t work so well. In theory, if the C:N ratio is right the heap should heat up and stay hot as expected, but for some reason in practice the fresh manure seems to get the whole thing hot and going far better for me than without it.

    I would reinforce that the other thing that seems to make a big difference is keeping the heap evenly moist. I keep mine loosely covered with black plastic to keep out any heavy rain (to avoid cooling it too much by becoming waterlogged – also a contributor to my heap that cooled too soon), and to keep the moisture and heat in. In a sunny spot with the black plastic on, I’ve found the outside of the pile stays much more moist and composts better than if the heap is open and dries out somewhat on the outside. (I am composting in Melbourne, Australia – the black plastic may be superfluous in warmer and/or more humid climates).

    Em – keep at it! The process may require some fine tuning and trial and error until it works best for you and the materials you’re using, but it’s worth it for the lovely fine, rich compost at the end. An alternative to sieving your compost may be to chop up the woodier material (eg woody vines) a bit more with a spade and return it to the heap, depending on how woody it is overall.


  116. Thank you for this wonderfully explained post, me and my husband started our pile today! This is very educational to us and appreciate it

  117. I have a question, today’s day 3 of my compost and I have notice a little shrinkage, my question is does a little bit of shrinkage suppose to happen?

    1. If your materials are coarse or there are air spaces in the pile then it will settle slightly as the materials break down and the spaces get filled in.

  118. Thank you for your excellent resource.

    Just finished sifting the results of my second hot compost pile following your recipe. Beautiful rich material 🙂 Setting up for my next pile. I shred all my materials using a leaf shredder. Is your 1/3 green to 2/3 brown more correct for unshredded materials where the brown has a lot of air spaces in it? Should I be looking more at half green to half brown?

    Also I have kitchen waste with some scrunched up paper in it from a cold compost bin with has built up over the past 8 months. I would like to add this to my hot compost as I really need to use everything to add bulk. Do I consider this to be green in my ratio calculations or neutral? That is, layer it in thinly but don’t count it in my green layer to brown layer ratio?

    Any suggestions would be very much appreciated.

    1. You’re welcome!
      The ratio of 1/3 green to 2/3 brown stays the same whether shredded or unshredded, the brown material may have more air in it, but the green material is just filled with water instead.
      If your kitchen waste has a lot of paper in it, as per the ratio just mentioned, then it’s balanced in its C:N ratio, if there’s not much paper, treat it as ‘green’.

      1. Thank you Angelo, appreciate you getting back to me and so quickly too.

        The kitchen waste is “green” even though a lot of it is old having been in the cold compost bin for many months?

        I think I will need to add some hay to my hot compost to umph up my “brown.” Does it matter if the hay is not certified organic?

  119. Actually just look again at your info and hay is “green”. Sorry! but still interested to see what you reckon about whether it matters if the hay is not organic.

    1. Hot composting can break down a lot of contaminants in composting materials that can be broken down, and the organic matter is capable of binding many contaminants that don’t readily break down, locking them up.

  120. Another question, sorry, should have thought of all this for my first message. My brown is dried leaves, shredded dry sticks, dry bambo leaves and stems. I have more bambo than leaves or sticks. Is this an issue? Is bambo an ok ingredient?

    1. Bamboo is a grass, and it is also a woody material. Woody materials contain lignin, which breaks down to create the most stable humus. Bamboo is a great ingredient to add to your compost if it is chopped up finely or mulched.

  121. Thank you Angelo, it’s so good to have your expert input – my delicious hot compost pile is now doing it’s thing it has a wide range of ingredients including a good mix of shredded bamboo – very exciting! Happy holidays in the garden to you.

  122. I there, if I understand well, it means I can use moose poop in that?
    Awesome! I’m gonna start collecting a good pile this winter! (It’s easier to stack in winter).

    1. Also, if everything that was once alive can be composted, then that would include my cat’s hair right? He looses a lot everytime I brush him.

      So the question is, does cat hair count as “brown”?

      1. Yes, cat hair and human hair can be composted, it’s actually very high in nitrogen so it counts as ‘greens’.
        If you brush your cat, collect the hair and hot compost it. Consider what happens in nature, when animals walk around in their natural habitat, they drop their hair. When then moult going from the cool to warm seasons, they lose a lot of hair, which falls to the ground and is broken down along with all the leaves and other plant material.

    2. Please DO NOT use mouse droppings, they may carry hantavirus which causes Hantavirus Pulmonary Syndrome (HPS) in humans, a severe respiratory disease which can be fatal. The disease is spread by breathing in dust that is contaminated with rodent urine or droppings, or through direct contact with rodents or their urine and droppings. It is not worth the risk for the tiny for the tiny amount of nitrogen containing material you would get.

      1. Ah, not Mouse. Moose. We have a land with a bunch of those big fellas and when we go snow shoeing, there’s often those huge pile of Moose poo and sometime it’s still steaming. It makes us both relieved and pissed off because sseeing a Moose is really awesome… except if it decides to charge you. You can never outrun a Moose… ever.

        Skidoos are barely fast enough.

      2. My apologies, I quickly read your question after a long day at work and misread moose for mouse! 🙂

        Those giant herbivores would generate a lot of manure, so yes, that can definitely be used in your hot compost!

        With permaculture one of the design principles (Attitudinal Principles – Everything works both ways) discusses how we can assess something that we perceive as a problem and reframe it so it is something we can gain benefit from –

        This is one way of utilising a ‘problem’ as a something of benefit!

      3. We have kangaroos here instead, luckily they aren’t found near our urban areas! Our biggest ones, the Red kangaroos, according to national geographic, can reach speeds of over 35 miles (56 km) an hour, and they can cover 25 feet (8 m) in a single leap and can jump 6 feet (1.8 m) high. They can weigh up to 200 lbs (90 kg). They don’t run, they hop, and can jump over fences easily. Moose are definitely scarier though! 🙂

  123. Thanks, I’ll keep you updates on my moose compost then!

    Right now, I’m thinking of using moose manure, lots of kitchen scrap (mostly vegerable peels), cat hair, thin cardboard (empty toilet paper rolls), bits of newspaper, green grass (when I’ll have that… Right now it’s as if I’ll never see grass again, ah the harsh winters…) rest of coffee too

    Oh, and I have tons of sawdust at hand. I really mean TONS

  124. Hi,
    i have recently attempted your hot composting method and have found it very useful and the concept of having compost in 18 days very exciting! today is day four for my compost, and i think i may have added too much green products. i made the pile out of horse manure, a little cow manure, paper, lawn clippings, kitchen scraps and a little garden waste. on turning it today, i have found that it has heated up but…i think it is a bit too wet. i then proceeded to add more dry garden waste. should i just wait a couple of days before adding anything else? and if i should add anything else to increase the carbon, should it only be sawdust as you mentioned?
    kind regard

    1. Was your compost pile really too wet? I’ve described how to test if it is in the Day 4 instructions – “Ensure that moisture stays constant. Put gloves on and squeeze a handful of the compost materials, should only release one drop of water, or almost drips a drop.” In that section I also mention how to fix the problem, which doesn’t involve adding extra material!

      If you’ve added some dry material to fix the problem with the pile being too wet, and there is enough nitrogen-rich material, than that’s all you have to do. Just continue following the steps. Hope this helps!

  125. Hi,
    I notice that there is mention of methane being released. Do you know what evidence there is for this, how much is released and how it can be reduced?

    1. When the hot composting process takes place, oxygen is required by the aerobic bacteria. In tiny spots here and there within the compost pile where oxygen momentarily is all used up, the process reverts to anaerobic breakdown and this is when methane and nitrous oxide are produced.

      This is one reference on the subject:
      Jckel, U., Thummes, K. and Kmpfer, P. (2005), Thermophilic methane production and oxidation in compost. FEMS Microbiology Ecology, 52: 175184. doi: 10.1016/j.femsec.2004.11.003 – read article here

      A highly aerobic system such as the hot composting system minimises the production of these gases, whereas an purposefully built anaerobic digester designed to capture methane gas as a fuel intentionally maximises methane production.

      Let me put this in perspective though – methane is a natural part of the carbon cycle and is produced naturally under conditions of anaerobic decomposition, in swamps, in the breakdown of plant material on forest floors, everywhere where carbon containing material (all living things) break down in the absence of oxygen, including us when we are buried!

      There is no issue with natural processes creating methane, it is produced as part of nature’s essential processes of the carbon cycle which perpetuate life. People fussing over flatulent cows are misguided and missing the point. Do we kill all the cows because they have wind??? What we need to take issue with is anthropogenic greenhouse emissions, the release of greenhouse gases through human activity which does NOI sustain life, and which is non-essential, that is the real problem!

      Hope this puts the whole issue of greenhouse gases into perspective.

      1. Thank you for the very quick reply.

        I totally share your comments regarding the overall picture.

        I was curious about the down side, because I feel there is a very considerable up side that seems to be slightly overlooked – unless I have got it wrong. We agree that cold composting drastically reduces the volume of the compost heap over time. This is because the contents are lost as carbon dioxide, water and small amounts of nitrogen gases. The fact that the volume of a hot pile is not reduced in the same way, surely, indicates much reduced losses of CO2 etc.

        In addition to retaining much higher levels of carbon and nitrogen the Berkeley method appears to be preferable to cold composting in terms of the net greenhouse gases emitted. Is this how you see it or have I overlooked something?


      2. Yes, that’s right, the hot composting method is a highly aerobic process which does not decrease in volume like cold composting, and loses the least nitrogen and produces the least methane of all the composting methods!

  126. Hi,

    I am enthusiast new gardener and to save bucks I tried your idea and gather
    1. Straws (brown Material)
    2. Goat Pallet (Manure)
    3. Kitchen Waste (Green Material)
    4. Chicken beat (Manure)
    5. Some leaves
    And follow the instructions exactly as you mentioned starting from 05th Feb 2015. All was good and accordingly as told in the article but then suddenly heat vanish and all almost cooled down and I can still see all the coarse brown material as is (in kitchen waste I used Peanut shells which are still almost the same nothing broken and goat pallet still round and running like a ball)
    Today (5th Mar 2015) it is 30th day. I do not have Thermometer available for now so don’t know the exact temperature but for sure while turning I cannot feel any heat nor can see the smoke and it appear to be cooled down but still I can separate straws, peanut shells, goat pallet etc but no green material can be differentiated. So what to do now? is it ready? or I have to do something like grinding? I do not have garden so I am doing all this on my roof top and I have all the pictures available and can share if you like.
    Awaiting for your guidance.

    1. I’ve just read through all the comments and it sounds like there was not enough green stuff (nitrogen) to start with… You could try adding a few handfuls of blood and bone or some more high nitrogen manure…. I defer to the experts who I am sure will comment soon but maybe after so many days ‘cool’ it might be too late to bring it back to life…?

      1. It is now almost a week in cool state I do have a bucket of green material available (kitchen scrap) which can create a layer or two so should I add that and give it a try? and should I water all again to made it wet will that help?

      2. If that cannot bring back to life (finished compost) than what alternate options I do have? What can I do with that stuff to make it useful somehow so that it cannot be a complete pile of waste.
        Thanking you in anticipation for all the help one can provide.

      3. If the compost heap has cooled right down, it means you did not have enough nitrogen-containing materials to begin with.
        It is best to start a new hot compost heap, and you can use your material that is not completely broken down as the carbon-containing material in the new compost heap.

      4. Thanks Angelo, Few more questions just to make sure I do not end up on wrong end.
        Following material I need to use to create new heap
        1. Brown Material (current compost heap)
        2. Cow / Chicken / Goat manure
        3. Kitchen scrap / Grass / leaves (Green Material)
        4. Water them to made it all wet and do I need to water them again while turning?
        5. Anything else to add?

        Sorry for asking such basics questions but just to make it successful this time I need to know these.

      5. Sounds good, only water when the instructions guide you to, and follow the steps from the beginning, hopefully it will work this time. Please let me know how you go.

      6. Thanks for your help
        I will start again in few days time and for sure will update my findings thanks again

  127. It is now almost a week in cool state – I do have a bucket of green material available (kitchen scrap) which can create a layer or two so should I add that and give it a try? and should I water all again to made it wet will that help?

  128. Hello Angelo,
    Thank you for your inspiring and helpful instructions.
    We need your advise.
    Our compost is on its 17th day.
    *The size of our pile is not exactly 1 m3 (about 0,60-0,70m3)
    *It smells very good
    *The weather temperature is around 8-20 celcius. When it rains we cover the pile.
    *We can observe the decomposing process, the colour is getting darker each day but
    Its COLD 🙂 On the very first days it was getting hot but somehow the temperature didnt rise again.

    *What shall we do now? Do you have any suggestions?

    1. Does it look ready? If the compost has broken down into a really fine, dark mix that smells nice and earthy where you really can’t recognise the original ingredients, that’s what hot compost looks like when it’s completed. It should stay for longer than just one day though.

      1. Thank you for your quick response Angelo. I am sorry 🙂 I should have given you more details about the situation. They started to brake down but we still can recongnise some of them.? We think that the reason is the size of the pile, as I wrote you yesterday it’s less than 1m3. Is it okey to add something more at this point?

      2. It sounds like your compost ran out of nitrogen and cooled down. As per my reply to a similar question earlier to Jawad, “It is best to start a new hot compost heap, and you can use your material that is not completely broken down as the carbon-containing material in the new compost heap.” Just add more nitrogen containing materials and it should work this time around. Try to get that critical size of one cubic metre or more this time though.

  129. Thank you sharing this article
    Built my first hot compositing heap just 10 days ago using this 18 day method temp is steady at 55 deg C. it is made up of cardboard leaves, grass clipping and coffee grounds. we did have an issue at day 6 with smell and a decrease in size, which we got from it has too much nitrogen, that we corrected quickly.

    It is built in wheel bin that has been modified to compensate for the width restriction. It is a flow through system with a large access port at the bottom for turning. We use a metal rod placed on top of the compost heap to know when it has completely turned ( we see the rod in the bottom ).
    We are using this method to make compost but also heat our underground walipini polytunnel in spring this year and hopefully autumn and winter.

  130. I live in the city and have a difficult time in finding enough leaves, weeds, etc. (let alone animal manure)… Anyway, I have finally managed to get a heap of only around 90cm tall. Must I get it up to 1.5 m tall? Also, I forgot to cover the heap and it’s raining quite heavily (I’ve just started creating the heap). What should I do now? Thanks

  131. I love hot composting myself. The best way I have found to get large amounts of material to make a big batch is by bagging by grass clippings mixed with leaves. That combination of fresh clippings with shredded leaves is dynamite in a hot compost pile. Mowing leaves and grass together. It gets hot quickly, it’s free, and as long as the weather isn’t really cold (sub-freezing) it finishes in two weeks every time. Great topic!

  132. I have been cold composting …just because it is convenient to add a small amount of kitchen scraps, straw from the chickens and garden rubbish to a pile every couple of days …can I now incorporate this into a hot compost pile?

  133. Hello again,
    You can see my first question 4-5 comment before.
    We have started a new compost pile as you said. At first everything was great and it worked but it cooled down again. I think we couldnt make small enough the ingredients. So, we gave up of hot composting for this time :/

    Now, the question is: Can we go on -with this pile- with COLD COMPOSTING? There were limes, lemons, oranges ect…. How can we go on with cold composting? Thank you in advance.

    1. If the hot compost pile cooled down and you want to use the material for cold compost, that should be fine. Cold composting is slow but you can speed it up by turning it every now and then to mix it up. I’ll write an article on cold composting soon!

  134. Two questions. Can I achieve hot compost with only two materials, horse manure and old slightly rotted mouldy hay? If so, is it a 50/50 ratio? Also, can I get this started when daytime highs are 10 c and lows are around freezing point, or is it just too cold?

    1. With a nitrogen rich and a carbon rich material you can make compost, including hot compost.

      As mentioned in the article, the if you don’t want to calculate C:N ratios just aim to use 1/3 Manure and 2/3 dry carbon materials. That means use two buckets of hay for each bucket of horse manure.

      Cover it with a plastic tarpaulin sheet if it gets too cold, his will help retain the heat.

      1. I am very confused about hay and straw. You advised Sarah (April 13) to use two buckets of hay for each bucket of horse manure but your chart puts hay into the Nitrogen list and straw in the Brown list. What is the difference between hay and straw?

      2. Hay and straw are quite different. Here’s a good explanation from the US Forage Export council website

        “People unfamiliar with our industry are often confused by the words straw and hay and mistakenly think the terms are interchangeable. Theyre not!
        Both straw and hay can be called forage but theres an important distinction between the two.
        Straw is a by-product of seed (or grain) production. For example, a farmer who grows wheat will harvest the grain; the dry plant that remains after harvest is straw…
        Hay is grown specifically, and its cut before the plant goes to seed. Because the plant pumps nutrients into the seed or grain, hay will have more nutrients than straw…”

      3. Hello, it is Elizabeth again! I understood your reply about hay and straw but I have a field
        which every year grows waist high “grass” which my neighbour cut down for his cows – what have I got, grass, hay – and straw stubble? I do not know what was originally sown in the field and I would like to try hot compost. Please clarify, Thanks

  135. Hi,

    My moose manure hunting is going quite well (even saw one of those big pooper) and snow is finally melting down. Should be able to have enough material to start my pile soon!

    Hey, speaking of snow melting down, can I use my dog’s manure in the pile? Because there’s plenty of it everywhere now. A lot of it is half degradated (or is the right word degraded? Well breaking down anyway). There’s plenty everywhere in my backyard.


    1. Hi, you can use any manure in a compost heap and the heat will break it down, but the problem with using dog poo is that it contains lots of nasty pathogens, and the risk to humans is in the collecting and mixing stage of composting, especially if it’s dry the dust can be quite harmful. There’s also the risk that in the turning of the compost that some gets spilled to the side and doesn’t get heated adequately to sterilize it. Safer to use manure from herbivorous (plant-eating) animals. Some people use dedicated worm farms for pet poo only and you can get specially designed ones that sit partly buried in the soil.

      1. Thanks. Luckily for me, the dog manure I grabbed was quite damp from all the melted snow. I think of using the compost from that pile for my flowers and on the spot I’ll eventually plant my blueberrie bushes. There’s not that much dog manure compared to all the rest of my greens

  136. Hi,

    Q1. When a compost is done or almost done, does it need to be kept moist (by misting/watering) and ventilated if not used.

    Q2. My compost has been fed with various material such as bonemeal, chicken manure, organic NPK fert., egg shell, UCG, tea leaves, kitchen scraps (no meat), etc. When its done, there would be an imbalance in the N, P and K or even the trace minerals. One would be higher than the other. Would it affect the uptake by the plant – caused by too much of this or that?. For example, too much nitrogen affects fruit/flower bearing plants as I understand.


    1. Just keep it covered so it doesn’t dry out.

      Your compost is a nice mix of ingredients, it should be of very high quality. Your concerns about NPK are more relevant to fertilizer than compost. Compost is not fertilizer, it is actually a soil conditioner which contains nutrients, and it is a living material in a state of ecological balance because it is a habitat for all the microorganisms in it. Even with compost, your soil (and plants) still need some form of fertilizer for bulk nitrogen in spring and autumn, especially if you have heavy feeders such as annual vegetables and citrus trees.

  137. I am trying to make my piles get hot. my piles are 7 feet tall 16 feet wide and 250 feet long. I am using grass clipings, wood chips, leaves and sludge. I have temp probes in the piles as required by my state to keep the pile at 131 degrees and turn 5 times in 15 days. I can get the temp to the mark I need but I can only keep it there for around 5 days. I have a large windrow turner. any suggestions on how to keep the pile going longer? when I turn the pile it cools way down and basically by the time to turn the 3rd time it gets to cold for to long and I have to start all over again

    1. Goodness, that’s commercial scale hot composting! The temperature of 131 degree Fahrenheit = 55 degree Celsius so it’s holding the right temperature, but not long enough.

      I have a few questions I need to ask:

      What season are you observing this, is the weather warm or cold?

      Does it break down into really fine, dark, compost after five days, or are parts of the original ingredients still identifiable?

      Is the right moisture level being maintained, how are you doing this, are you using an automated hydrating system, or is it getting too wet and cooling down from excessive rain?

      Turning should cause the temperature to rise because it brings new material deep into the compost pile to feed the bacteria and lets more oxygen in. Turning every three days should make the compost pile much hotter than less frequent turning.

      If the weather is very cold you might need to make the pile larger to offset the loss of heat from the surface, or are you running the piles at the maximum size for our machine?

  138. Dear Sir, I’m working in Compost making for Muncipal waste. I am really intrested about your hot composting, which can be compost within 18 days. At the moment, one cabine is about 35  cm3 (5.3m x 4m x 1.7m) I used to pile the organic waste, it takes long time to matured. So I would like to follow your suggestion. Turning the pile alternately. It takes 5 to 6 months to mature. The picture shown is my old picture. Now 6 cabin is full and have a plan to do more cabine to place the compost pile. But just keeping waste is not a sollution for me. I need to know how to do fast composting. So I found your hot composting is a good solution. Looking forward to see your kind help. Thank you.

     Monu Jyothi Tamang Sr. Technician Solid Waste & Sanitation Environment Division Thimphu Thromde +97517703979

    1. For that quantity of compost you can turn it using a specialized windrow compost turner or you could use a front-end loader to turn it, and it will heat up and produce compost in 18 days.

  139. Great post , at the moment we are trying to get our beds started and as there is lots of really tough grass in clumps it means sometimes we need to dig these clumps out before cutting and covering with cardboard etc, so we have lots of piles of these clumps of matted grass with soil attached they are thrown into the heap to make compost alongside veg peel and grass cuttings and now and then I add a layer of straw to provide more air however the most of the pile is these clumps of grass with attached soil and my question is should I add something else to even the ration a bit .

  140. It seems I am learning in the wrong order! I have just made my 1st compost pile, 4’x4 and about 3-4′ high. Mostly contains weeds, also house veggie/fruit scraps, and some dried leaves as well. I am now concerned about the weeds and seeding them all through my gardens! Have come across your article about hot composting. At first I thought your 30:1 ratio of Carbon:Nitrogen was by volume but I think that is wrong? Looking at your charts, things like veggie scraps and weeds put me right at 25-30:1, right where I need to be? Add in the dried leaves and I should be good? How do you factor in adding shredded newspaper that has such a high C:N? How do you determine volume of what is needed? This is the part I find so confusing. The turning of the pile is the easy part ;).

    I’m not sure if I need to load up the whole pile and just take it to my organics section at the local dump and start over with no weeds. I was ok to cold compost and wait till next growing season for it to be ready but the weeds have me significantly concerned. Will hot composting break down the weeds that spread via runners/roots as well??? Thanks for your help.

    1. I should also add I have horse manure/saw dust compost that could be added. I just got it the other day to add to my sandy soil to make my new raised veggie beds. It is 3 yrs old and she figures it is 50/50 manure to sawdust. It came from horse stables.