Gardening Calendar (Australian Temperate Climate) – November

It’s November, the last month of spring, the weather is moderate, deciduous trees are in leaf again, days are warm and there’s lots of green growth in the garden. The changeable and windy weather from October continues, but now there’s also the possibility of very sudden hot weather striking without warning so it’s important to protect plants from sun and wind. Also, regularly water newly planted trees and shrubs as the hot weather and strong winds can quickly dry out the soil.

Things to Do This Month:

  • Mulch around fruit trees and plants to retain moisture in the soil and prevent water loss from
    evaporation (keep mulch away from plant stems and trunks as this can cause stem rot/collar rot).
  • Mulch strawberries by placing straw underneath to keep the berries off the soil.
  • Propagate strawberries from runners.
  • Plant potted fruit trees and vines (having roots, can be planted anytime, best in spring & autumn).
  • Tie growing vines back to supports or wires.
  • Propagating plants by taking softwood (green) cuttings from now till January (after which they
    harden off).
  • Last chance to plant evergreen shrubs and trees (this includes citrus trees).
  • In ponds and water gardens, thin out existing aquatic plants, continue planting new ones, fertilise
    aquatic plants and feed fish regularly.

Vegetables and Herbs to Sow:

Sow in November   Harvest (weeks)
Amaranth ds 7-8
Angelica ds 18 months
Asparagus d 2-3 years
Asparagus Pea d 8-11
Beetroot ds 7-10
Borage ds 8-10
Burdock d 17-18
Cape Gooseberry ds 14-16
Carrot d 12-18
Chicory d 16-24
Chinese cabbage ds 8-10
Chives ds 7-11
Climbing beans d 9-11
Coriander d 30-45
Cucumber d 8-10
Dwarf beans d 7-10
French tarragon d 30-40 days
Globe Artichokes s 42-57
Horseradish d 16-24
Jerusalem Artichokes d 15-20
Kohlrabi d 7-10
Lemon balm s 8-10
Lettuce ds 8-12
Mustard greens d 5-8
Okra ds 11-14
Oregano s 6-8
Parsley ds 9-19
Pumpkin ds 15-20
Radish d 5-7
Rhubarb d 12 months
Rocket d 21-35 days
Rosella s 21-25
Rosemary d 12 months
Sage d 18 months
Salsify d 14-21
Silverbeet ds 7-12
Summer savory d 6-10
Sunflower ds 10-11
Sweet corn ds 11-14
Turnip d 6-9
Yacon d 25

Key:
d = sow directly into ground
s = sow in seed tray
ds = sow directly into ground or seed tray
*= frost tender
**= sow after frost

Download printable PDF version of Gardening Calendar (Australian Temperate Climate) – November

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Layering Overgrown Tomato Plants

totato-layering

Indeterminate (vining) tomatoes are very vigorous growers, and if they’re neglected they can easily become overgrown, with multiple tangled branches sprawling across the ground. If this happens to your tomato plants, all is not lost. In fact, you can take advantage of the situation to make the plants even more productive, and tidy them up in the process, using a technique called layering.

 

Problem or Opportunity?

In Permaculture’s design principles, we have the Attitudinal Principle – Everything Works Both Ways. Whether we see something as positive or negative, as a ‘problem’ or as a useful resource, depends on our attitude. Typically, people see a disadvantage as a ‘problem’ and then implement an energy-intensive ‘solution’ to attempt to ‘fix the problem’. The other option is to take a different attitude, look at everything as a positive resource, and figure out how to make use of it! We can get creative and think of all the ways we can turn these disadvantages into useful things we can use in our system. In this article we’ll look at one such practical application of this principle.

 

How Layering Works

Layering is a propagation technique where a portion of plant’s branches are buried below the soil in order for them to produce roots.

Sometimes, the underside of the branch is scraped to injure the outer bark (to expose the green cambium layer underneath) or surface layer (in herbaceous non-woody plants such as tomatoes) in order to promote root growth. Additionally, the scraped underside of the branch can be treated with rooting hormone to enhance root production even further.

The branches which are layered are held in place beneath the soil with upside-down ‘U’ or ‘J’ shaped wire pegs such as weedmat pins or irrigation pins, or homemade fateners made out of coathanger wire. Alternatively, heavy stones or half-bricks can a;so be used for the same purpose.

Once rooted, the branches are cut off the parent plant to produce separate plants, but with layering tomatoes they don’t have to be removed at all!

It’s important to keep in mind that the technique of layering will only work with plants that are suited for propagation with this method. Any one propagation technique will not work with every plant, which is why we have so many propagation techniques, such as grafting, growing from cuttings, division, and so on.

simple-layering-propagation
The method of layering a plant to stimulate root growth in the branches

 

Layering Tomato Plants

One of the interesting features of tomato plants is that if they’re planted deeper than normal, the section of the stem below the ground will also grow new roots. Many gardeners take advantage of this phenomenon and plant their young tomato plants deeper into the soil, allowing the plant to start off with its roots deeper into the ground to access more water and nutrients, leading to faster establishment.

Similarly, when tomato plant branches are buried in the soil, they also sprout new roots, making them suitable plants for layering.

To layer a tomato plant:

  1. Separate and untangled the branches from each other.
  2. Lay the braches down so that they’re spaced apart at the same distance that you would plant individual tomato plants.
  3. Anchor branches in place beneath the soil.
  4. Stake ends of branches vertically.

To get an idea of spacing, we can look at example which I’ve prepared. Pictured below is a self watering planter in which appears to be growing five tomato plants, but actually there’s just one plant with five branches in there which has been layered. This plant was a self seeded cherry tomato which grew very late in the season and survived right through winter, becoming quite heavily branched and overgrown. It’s well ahead in terms of growth, as it’s only the start of tomato planting time here where I live, yet this plant is already producing its first tomatoes! It would be a shame to prune it back and lose a lot of productive growth, so instead it can be further encouraged!

tomato-layered-1
A single tomato plant layered to produce five plants evenly spaced in a self-watering planter box

 

If we take a closer look at the potting medium, we can get a better idea of what’s going on here.

tomato-layering-2

Not clear yet? It may help to show what’s happening beneath the soil…

The dashed green lines show where the branches originate from the main root. From the diagram it should be a bit more obvious that the big pieces of broken red brick are there to hold the stems down below the soil.

tomato-layering-3

 

Taking a closer look at a layered branch, it comes up from the main root, and runs below the soil where it’s held in place with a weedmat pin. the end of the branch is supported vertically with a bamboo plant stake, and it’s held there with a wire plant tie.

tomato-layering-4

 

To layer the branch, simply dig a narrow trench in the soil, lay the branch down in it, then anchor it in place with a weedmat pin. Cover with soil, then stake the end of the stem vertically.

tomato-layering-5
Layering, anchoring a branch down below the soil with a weedmat pin

If using a rock to hold the branch down, once again, dig a narrow trench in the soil to lay the branch down in, hold the branch down by hand and cover with soil, then place a reasonably heavy rock on top of the soil to anchor the branch down. Once that’s done, stake the end of the branch vertically.

tomato-layering-6
Tomato layering, branch anchored with broken half brick – a heavy stone works just as well

 

Pictured below, one plant is now five healthy plants, each will grow its own roots, and there’s no need to separate them, they all have the main original root and their new roots under the layered section. Each new layer can be pruned to a single stem and supported on a stake or string for a high density planting, as described in my previous article – Small-Space Intensive Tomato Growing

tomato-layering-7

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Gardening Calendar (Australian Temperate Climate) – October

October is the mid-spring period, flowers bloom in abundance, the warmer weather with rain bringing ideal conditions for lush plant growth. The cold weather hasn’t quite finished yet, cold nights and even frosts can still be expected, along with strong winds, so it’s important to protect tender plants and seedlings.

Things to Do This Month:

  • Plant evergreen shrubs and trees (this includes citrus trees).
  • Relocate evergreen shrubs – they can now regrow their roots during the mild weather.
  • Set up windbreaks (e.g. plastic tree guards) to protect newly planted evergreen trees and shrubs.
  • Plant potted fruit trees and vines (having roots, can be planted anytime, best in spring & autumn).
  • Relocate any self-seeded annuals to better locations in the garden.
  • Tidy up overgrown plants and tie growing vines back to supports or wires.
  • Continue propagating plants by taking cuttings or layering (both ground layering and air layering).
  • Feed brambleberries (raspberries, blackberries & hybrids) and currants.
  • Last chance to remove dead winter growth, and to dig up and divide perennial plants
  • Clean out ponds and water gardens, divide waterlilies, plant new aquatic plants.

 

Vegetables and Herbs to Sow:

Sow in October   Harvest (weeks)
Amaranth ds 7-8
Angelica ds 18 months
Asparagus d 2-3 years
Asparagus Pea d 8-11
Beetroot ds 7-10
Borage ds 8-10
Burdock d 17-18
Cape Gooseberry ds 14-16
Carrot d 12-18
Celeriac s 14-28
Celery s 17-18
Chicory d 16-24
Chinese cabbage ds 8-10
Chives ds 7-11
Climbing beans d 9-11
Coriander d 30-45
Cucumber d 8-10
Daikon d 8-10
Dill d 8-12
Dwarf beans d 7-10
Endive ds 10-11
Fennel d 14-15
French tarragon d 30-40 days
Globe Artichokes s 42-57
Horseradish d 16-24
Jerusalem Artichokes d 15-20
Kohlrabi d 7-10
Lemon balm s 8-10
Lettuce ds 8-12
Marrow d 12-17
Mustard greens d 5-8
NZ Spinach s 8-10
Okra ds 11-14
Oregano s 6-8
Parsley ds 9-19
Parsnip d 17-20
Potato d 15-20
Pumpkin ds 15-20
Radish d 5-7
Rhubarb d 12 months
Rocket d 21-35 days
Rockmelon ds 10-16
Rosella s 21-25
Rosemary d 12 months
Sage d 18 months
Salsify d 14-21
Silverbeet ds 7-12
Spring onions d 8-12
Summer savory d 6-10
Sunflower ds 10-11
Sweet corn ds 11-14
Sweet marjoram s 8-10
Turnip d 6-9
Yacon d 25
Yam/Oka d 15-20

Key:
d = sow directly into ground
s = sow in seed tray
ds = sow directly into ground or seed tray
*= frost tender
**= sow after frost

Download printable PDF version of Gardening Calendar (Australian Temperate Climate) – October

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Community Event – Warrandyte Food Swap

I’ve been asked to promote a free local community event in Warrandyte, Melbourne, Victoria, Australia – the Warrandyte Food Swap!

food-swap_Page_1

Warrandyte Food Swap

Join us for the 3rd Birthday Celebration

Sat 6th October 2018

9am – 10am

Warrandyte Community Garden

Live music, fresh produce, free seeds, and most of all….friendly faces

food-swap_Page_2

 

"Flashback from last years birthday celebrations.  This year we celebrated new baby Lachlan, 2 university graduations, woofing in Canada, a plum role in the outback, winter in the Scottish Highlands and spring on a Qld beach.  Along the way we enjoyed great produce, luscious greens, tomatoes, cumquats, lillypilly, macadamia, turned grapefruit into conserve, chilli into ripper salads, all the time sharing stories enjoying community.   A big shout out to Glenn and Chris for their constant support.  Come and join us October 6th at 9am"

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Small-Space Intensive Tomato Growing

tomato-plants-vining-string-support

Want to grow lots of tomatoes in limited spaces, even containers? Ever wondered how the commercial hydroponic growers pack in as many plants as possible in their growing areas? By understanding the way tomatoes grow, we can select the right plants and utilise their growth habit for maximum production in the smallest of spaces.

 

Determinate Versus Indeterminate Tomatoes

Tomato varieties are classified into two categories based on their growth habit, determinate and indeterminate.

Determinate tomato varieties are known as ‘bush tomatoes’, they grow into a self-supporting small bushes up to 1.2m (4’) tall that don’t need staking, They grow to their full size, then produce flowers at the ends of all their branches (shoots), producing all the tomato crop at once.

Indeterminate tomato varieties are known as ‘vining tomatoes’, they grow very long stems around 2m (6’) tall which branch heavily and require staking or tying to a support to keep them off the ground, Flowers are produced along the sides of the branches (shoots), and the plants will continue to grow until the cold weather arrives.

 

Growing Indeterminate Tomatoes as Columnar Plants

Since indeterminate tomatoes flower alongside any new shoots that emerge, and continue growing after flowering, their continuous productivity makes them ideal plants for intensive growing systems.

A plant’s available growing energy can either go into vegetative growth (leafy green growth, basically leave and branches), or flowering and fruiting productive growth. We can direct the plants growth into flowering and fruiting simply by preventing the growth of new shoots (branches) by pruning them off.

Unlike determinate bush tomatoes which fruit at the ends of their branches and therefore need branches to fruit, indeterminate tomatoes don’t. A stem and leaves will do the job.

tomato-indeterminate-growth-habit

 

As we can see in the picture below, cutting off the new shoots (branches) growing from stem does not affect the flowers, as the flowers are produced on the stem.

indeterminate-tomato-pruning-shoots

If we prune off all new shoots (branches), we end up with a tall plant that is comprised of a stem with leaves along its length and flowers emerging from it –  basically a columnar (tall and narrow) tomato plant, the ideal shape for intensive plantings where many plants are fit into a small space!

indeterminate-tomato-stem-shoot

Don’t throw away any shoots that are pruned off, they can be very easily turned into new tomato plants! Just put them in a bucket with some water in the bottom, and locate in a protected area exposed to morning sun only.

tomato-cuttings-bucket

In a few days the cuttings will put out roots!

tomato-cutting-roots

 

Hydroponic-Style Supports for High Density Plantings

When tomato plants are pruned to be tall and narrow, they can space them quite closely, even in containers.

Pictured below are three tomatoes planted side-by-side in two self-watering containers, supported by strings attached to an overhead frame. The pots are 70cm (28”) wide, with the tomatoes spaced around 25cm (10”) apart, quite an effective use of space!

tomatoes-self-watering-containers

To support tomatoes on strings, as they do in hydroponic setups, attach hydroponic tomato clips (as pictured below) to the base of each tomato plant, then tie the string to the top of any overhead support, then wind tomato stem around the taught string.

image
Hydroponics tomato clip – plastic clips which hold string to base of tomato plant stem just above soil level

 

hydroponic-string-support
Hydroponic string support, constructed of thick galvanised wire, attaches to overhead frame

 

hydroponic-string-support-tree-tie
Hydroponic string support fastened to overhead support using plastic tree tie strip

Here is a tomato stem supported on a string, the stem is just wound around the string as it grows, and any new shoots (side branches) are pruned off. This maintains the narrow shape as the tomato grows upwards only.

indeterminate-tomato-string support

Using such a setup, it’s possible to grow tomato plants extremely closely, and it’s cheaper than using wooden stakes. The plastic string lasts several years, and is extremely cheap to replace.

I constructed my support frame out of square aluminium sections that connect with plastic fittings which just push together, all purchased from a local hardware store. Since these materials don’t rust or crack, they can withstand the weather and last almost indefinitely.

There is no limit to what can be used as an overhead support to attach the strings to. Two wooden tomato stakes in the ground with at third lashed to the top to form an inverted ‘U’-shape will work perfectly well in a garden bed.

For spacing, I’ve used a distance of 45cm (18”) between plants in the ground in garden beds, and in my experience this provides plenty of air circulation to prevent diseases. When planting in the ground, I always remove all leaves off the bottom 30cm (12”) of the tomato plant once it’s tall enough, as this prevents soil splash from the rain reaching the leaves which causes that all too familiar disease where to bottom leaves dry out and the infection slowly spreads upwards. Using a thick layer of mulch also helps considerably in preventing this problem.

In conclusion, we can exploit the growth habit of indeterminate tomatoes and borrow some tricks from hydroponic tomato growers to create high density, high productivity planting in the smallest of spaces. If you like experimenting and trying something different, I recommend trying these ideas out. Traditional tomato growers can still stake up and prune indeterminate tomatoes into columnar shapes this way to squeeze way more tomatoes into a garden bed than was ever possible!

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Gardening Calendar (Australian Temperate Climate) – September

It’s September, the beginning of spring, the time of new life and renewal! The weather is starting to warm up, but there are still cold days, rainy weather and winds to contend with.

Early spring is the best time to mulch garden beds, as the soil is still moist and is slowly warming up.

This month is the last chance to plant bare rooted deciduous trees and shrubs, as they need time to establish before the summer heat arrives. Container grown ones with well developed roots can be planted right through spring.

Things to Do This Month:

  • Plant evergreen shrubs and trees (this includes citrus trees).
  • Relocate evergreen shrubs – they can now regrow their roots during the mild weather.
  • Last chance to plant bare-root deciduous trees, shrubs and vines (otherwise wait till autumn).
  • Feed all fruit trees if you didn’t do so last month.
  • Clean up old growth in perennial herbaceous plants to make room for new growth.
  • Propagate plants by taking cuttings or layering (both ground layering and air layering).
  • Divide perennials, such as chives.
  • Tie canes of brambleberries to wires before the vigorous growth commences in early spring.
  • Plant passionfruit.
  • For seedlings raised indoors in August, harden off by slowly increasing sun and exposure to outside temperatures for 7 to 10 days before planting out.
  • In ponds, begin feeding fish small amounts of food often, so food is not left over to pollute water.

Vegetables and Herbs to Sow:

Sow in September   Harvest (weeks)
Amaranth** ds 7-8
Asparagus d 2-3 years
Asparagus Pea d 8-11
Basil s 10-12
Beetroot ds 7-10
Broccoli ds 10-16
Burdock d 17-18
Cabbage ds 8-15
Cape Gooseberry ds 14-16
Capsicum s 10-12
Carrot d 12-18
Celeriac s 14-28
Celery s 17-18
Chicory d 16-24
Chilli s 9-11
Chives ds 7-11
Climbing beans** d 9-11
Coriander d 30-45
Corn Salad d 5-8
Cucumber d 8-10
Daikon d 8-10
Dill d 8-12
Dwarf beans** d 7-10
Eggplant s 12-15
Endive ds 10-11
Fennel d 14-15
Globe Artichokes s 42-57
Horseradish d 16-24
Jerusalem Artichokes d 15-20
Kohlrabi d 7-10
Leeks ds 15-18
Lettuce ds 8-12
Luffa s 11-12
Marrow* d 12-17
Mint s 8-12
Mustard greens d 5-8
NZ Spinach s 8-10
Oregano s 6-8
Parsley ds 9-19
Parsnip d 17-20
Peas d 9-11
Potato d 15-20
Pumpkin* ds 15-20
Radish d 5-7
Rhubarb d 12 months
Rocket d 21-35 days
Rockmelon* ds 10-16
Sage d 18 months
Salsify d 14-21
Shallots d 12-15
Silverbeet ds 7-12
Snow Peas d 12-14
Spring onions d 8-12
Squash* d 7-8
Sunflower ds 10-11
Sweet corn** ds 11-14
Tomatillo s 10-14
Tomato ds 8-17
Turnip d 6-9
Winter Savory s 6-10
Zucchini* ds 6-9

Key:
d = sow directly into ground
s = sow in seed tray
ds = sow directly into ground or seed tray
*= frost tender
**= sow after frost

Download printable PDF version of Gardening Calendar (Australian Temperate Climate) – September

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The Difference Between Soft and Hard Mulches

garden-mulches

Hard woody mulches or soft non-woody straw-like mulches, what’s the difference?

They both work equally well as garden mulches to  moderate soil temperature, reduce water loss from the soil through evaporation, conserve soil moisture to reduce the need for watering, inhibit weed seed germination and suppress the growth of weeds.

Selecting the right kind of mulch is important, as it can make a huge difference to the quality of your soil over time!

Typically, woody mulches take longer to break down, usually around two years, as compared to six to twelve months for the soft non-woody mulches. But there’s more to consider than longevity, namely what happens when the mulches do break down, the ecological process of soil building and the carbon cycle.

 

The Carbon Cycle

Nature recycles everything! We’re all familiar with the water cycle, where rain falling from the sky soaks into the soil, the water is taken up by plants and transpired through their leaves back into the air as water vapour, which forms clouds and repeats the process. Well, there are cycles for all soil nutrients too, including carbon. Mulches are carbon-rich materials, so when they break down, they release carbon back into the soil. If there’s a carbon cycle, that would logically suggest that the carbon can move, and may possibly not stay in the soil.

Carbon_cycle
The Carbon Cycle – Diagram adapted from U.S. DOE, Biological and Environmental Research Information System (http://earthobservatory.nasa.gov/Features/CarbonCycle/)

When we look at the carbon cycle, we can see that carbon does indeed leave the soil naturally through microbial respiration and decomposition (as carbon dioxide), or through made made changes to the environment. That said, soil carbon is not all the same, and depending on the form of carbon we’re talking about, it may leave the soil very easily or it may be extremely stable and stay in the soil for a very long time.

 

Soil Organic Carbon – Labile and Stable Forms

Organic materials are essentially materials which contain carbon, the building block of all life on this planet. All living things are carbon-based life forms, us included! Soil is one of the most complex ecosystems on the planet, extremely rich and diverse in life, so it’s no coincidence that it contain a very wide range of organic materials, each with different chemical and physical properties.

Soil organic carbon in its various forms is generally divided into two major categories, labile carbon which decomposes relatively rapidly (days to years) and stable carbon which takes much longer to decompose (many years to decades to centuries). There is a further category of stable carbon, such as biochar, referred to as recalcitrant carbon which can last much longer, and may persist in soil for centuries to millennia.

Labile soil carbon is composed of small pieces of plant material 0.05–2 mm in size, as well as living organisms and the remains of dead organisms, all of which can break down relatively easily, serving as an energy source for soil organisms, and therefore able to be recycled through the carbon cycle.

Stable soil carbon is composed of much finer particles of organic matter that are either physically protected within clay for example, or are in a chemically-stable persistent form such as soil humus. In case you’re wondering, humus is ‘the black stuff in soil’, it’s essentially decayed organic matter which is very finely broken down and resistant to further breakdown, and it plays a very important role in the retention of moisture and nutrients in the soil.

When organic materials break down and decompose, what is basically happening is that soil microorganisms are breaking them down to use them as food, as an energy source. Since labile soil carbon materials break down more easily than stable ones, soils with more labile organic carbon will have a larger population of soil microorganisms feeding on them, and they will release more nutrients as a result of the decomposition process.

Now that we’ve made that distinction, it’s important to discuss which mulch materials create labile soil carbon, and which ones create stable soil carbon and a nice, dark, rich, long lasting humus.

 

Stable Soil Organic Carbon and Lignin

All woody plant materials contain lignins, complex organic (carbon-containing) compounds which play an important role in providing structural support of plant cell walls, particularly in wood and bark.

Chemically, lignins are cross-linked phenolic polymers – polymers are simply large molecules made up of smaller molecules repeatedly chained together. Plastics are synthetic polymers, and as an example, polystyrene is made up of many (Greek poly-, “many”) styrene molecules linked together. A cross-link is a chemical bond that links one polymer chain to another, creating a stronger structure.

Due to their chemical structure, lignins are rigid, and very resistant to decomposition and breakdown.

Bark contains more lignins than wood, and that would make sense as you would want the outside of a living tree to be resistant to decay! Therefore, mulches made of tree bark are higher in lignins than mulches made of tree wood alone, but both, when completely broken down into fine composted matter, create a dark, rich humus that is high in lignins, and therefore high in stable soil organic carbon.

 

Soil Carbon – Slow in, Slow Out, or Fast In Fast Out?

Woody mulches break down quite slowly, eventually releasing their lignin-rich humus, which is a stable soil carbon, into the soil. Since bacteria cannot readily break down stable organic soil carbon, it can last in the soil for years, decades or centuries. Over time, the soil will become darker and richer, improving soil quality.

biomat mulch
Woody mulches create a stable soil organic carbon – slow in, very slow out.

 

Gardeners who use non-woody mulches in their gardens during the start of the warm season usually notice that by wintertime the mulch will have all broken down back into the soil, depending on seasonal humidity levels.

Non-woody mulches include all the soft mulches, such as straw, lucerne, sugar-cane, and pea-straw, as well as any non-woody plant material that you may chop-and-drop on the soil surface. Non-woody plant material which is composted or buried in the soil acts in the same way, it breaks down very quickly, adding carbon the to soil very fast, because these are labile soil carbon materials.

Microorganisms are able to feed on labile soil carbon materials, and If we look at the the carbon cycle, just like us, they can engage in aerobic respiration, using oxygen and organic matter to produce energy, releasing the waste products water and carbon dioxide, the latter of which returns as a gas to the atmosphere, where it can be taken up by plants during photosynthesis.

straw-mulch
Non-woody mulches create a labile soil organic carbon – fast in, fairly fast out.

 

In Summary

Non woody mulches break down faster and more easily, adding to the pool of labile organic soil carbon, which is available to bacteria. The carbon enters the soil quickly, and leaves just as easily – Fast in, fast, out.

Woody mulches contain lignins, these compounds are complex organic polymers which provide structural support in the cells of woody plants and trees, and are resistant to breakdown and decomposition. Once woody plant material breaks down into the soil, the lignins remain, strongly binding the carbon for a very longer time, forming rich, dark soil humus. It takes a while for woody material to break down, and once the stable carbon is in the soil, it will remain there for a very long time – Slow in, slow out.

So, what should we use in our gardens, woody or non-woody mulches? The answer is WWND! (What would Nature do?)

In Permaculture, we emulate natural ecosystems, because Nature has perfected the process of soil-boiling and plant growing! What happens in Nature? We can look, observe and learn!

On forest floors we have a mixture of branches, bark and whole fallen trees supplying the stable soil organic carbon. These materials favour soil fungi and create a very stable, persistent soil humus.

We also have fallen leaves, and lots of other non-woody plant materials which supply the source of labile soil organic carbon, which favours soil bacteria, and the release of nutrients which become available for plants to use.

By adding both stable and labile soil organic carbon, we can enrich the soil and create a stable soil ecology which supports the growth of healthy and vigorous plant life, and that is what we should aim for.

In practical terms, we can take a Permaculture solutions thinking approach and get creative, here are a few suggestions which I use in my own garden.

  • If your garden beds use straw mulches, prune any woody shrubs and trees, chop up or mulch the woody material, lay it on the soil (and also add fertiliser and compost if you want to practise no-dig gardening), then cover with straw mulch.
  • If your garden beds use woody mulches, before replenishing the mulch, push aside any remaining mulch and dig compost into the soil, or empty your compost bin contents on the soil surface (and also add fertiliser if you want to practise no-dig gardening), and then add new woody mulch to the top.

In Permaculture, we look to Nature for inspiration, and to science for the explanations!

 

References:

  1. Soil Quality Fact Sheets Labile Carbon http://soilquality.org.au/factsheets/labile-carbon
  2. A Comparison of Landscape Mulches: Chemical, Allelopathic, And Decomposition Properties by Mary L. Duryea, R. Jeffery English, and L. Annie Hermansen
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