Everyone agrees gardening would be way more fun, and many people would be more inclined to take it up if it didn’t require all that back-breaking work, like digging… It may surprise many people, but digging IS NOT a necessary part of gardening at all!
So how did we get into the habit of digging up our gardens in the first place? It’s basically just an old tradition. Historically, people have treated their gardens like miniature farms. They saw how vast tracts of land were farmed and did the same on a smaller scale because that’s what they knew how to do.
You may be asking, “Why do farms till the soil anyway?” The answer is that tillage (i.e., ploughing) loosens compacted soil, making it easier to plant into, rips up weeds, and buries the scraps left over from harvesting.
This raises the logical question of why the soil is compacted in the first place if it’s constantly tilled. Several causes of re-compaction in tilled soil include animal-powered and mechanised farm equipment (such as tractors and oxen), people walking on the soil, and rain impacting bare soil.
Before we can understand why we don’t dig soil, we need to understand what soil is; otherwise, it’s unclear what we’re dealing with.
Why We Shouldn’t Dig the Garden!
The soil is not just ‘dirt’ to anchor plant and tree roots, though that’s how many people treat it! It is a complex ecosystem teeming with diverse life.
In fact, the soil is more abundant in life and more complex than any other ecosystem above the ground. There are about 50 billion microbes in 1 tablespoon of soil. By comparison, the human population numbers just over 7 billion. These organisms include Bacteria, Actinomycetes, Fungi, Yeast, Protozoa, Algae and Nematodes. Furthermore, there are arthropods and insects in there as well, including earthworms. That’s a lot of life in the soil!
So what are all these critters doing in the soil? Soil bacteria form a beneficial relationship with plant roots, and soil fungi form a beneficial relationship with tree roots, helping them access nutrients. The soil organisms carry out important functions, including nutrient cycling, improving soil structure to aid water and air movement through the soil, controlling diseases, and enhancing plant growth. Most of the soil fungi occupy the top 15 cm (6”) of the soil, while the rest of the organisms live at all depths.
Digging and turning over the soil exposes a delicate ecosystem to air, which dries it out, and to the sun’s ultraviolet rays, which sterilise the soil – killing the soil organisms. The soil loses many of its nutrients, such as carbon and nitrogen. It also loses much of its organic matter, and as a consequence, does not retain water as well. The delicate soil structure is destroyed, compaction occurs, leading to hardpan formation, reduced water infiltration, and more surface runoff, which increases soil erosion.
Tillage is the term used to describe the agricultural preparation of the soil by digging and turning it over. So why are farmers so fond of this destructive practice? They found that when you first dig up the soil, fertility goes up and plants grow better. The reason is that the bodies of the soil organisms that have just been killed by digging break down, releasing their nutrients into the soil. The catch is that it only works once, and then your soil is sterile. Plants are worse off, become more prone to disease, and require even more fertiliser than they normally would. To further compound the problem, chemical fertilisers are pumped into the dying soil, which effectively kill off what soil life is left. Yes, chemical fertilisers kill soil life! It’s really a fool’s game to destroy soil life for a short-lived, once-off nutrient boost, which shows gross ignorance and a complete lack of understanding of soil ecology and what makes plants grow!
That, in a nutshell, is why we don’t dig the soil.
Working With Nature, A Smarter Way to Garden
In Nature, soil does not need to be manually cultivated for spectacular forests to grow. What holds true in Nature also holds true in the garden. In a forest, organic matter in the form of fallen leaves, twigs and branches, annual plants at the end of their yearly cycle, and other plants at the end of their lives is deposited on the forest floor, where it decomposes into rich humus.
We can add organic matter directly to the soil surface, such as manure, compost, straw, and leaves. Garden waste, such as prunings from trees and shrubs, can be fed into a mulcher to break it down into smaller pieces, then spread over the soil as a mulch.
Adding a layer of organic matter over the soil, approximately 5-15cm (2-6”) thick, is effectively ‘sheet composting’, where the garden beds become large composting areas. Through the action of earthworms, bacteria, fungi and insects, the organic matter is slowly broken down and released into the soil, providing nutrients to the garden. Because the soil is not disturbed, a stable soil ecosystem is created, and plant health is improved. Moisture is also better retained due to the mulching, and the organic matter in the soil acts like a sponge to retain moisture. The mulching also prevents soil erosion, stops runoff of rainwater across the surface, and assists rainwater to percolate into the soil. The earthworms will create channels in the soil, which will help both water and air to penetrate into the soil.
How To Protect the Soil and Reduce Work
In no-dig gardens, the soil stays loose because it isn’t walked on! Walking on soil compacts it, blocking air and water from reaching plant roots, which harms plant health, stunts growth, and lowers yields. Paths are for people to walk on, while garden beds are reserved for plants ONLY! Keep these areas separate, and gardening will become much more productive and easier.
One thing I haven’t mentioned yet is that Nature does dig, but not in the way we humans do—it’s much more efficient, thanks to earthworms!
Earthworms Dig Better Than Humans
When there’s digging to be done, let the experts do the work!
Earthworms are Nature’s wonder creatures. They are a tireless army of super-efficient diggers whose abilities we humans cannot replicate, despite all the technology we have available. I keep stressing that Nature does it better than we ever could, but for those who need more convincing, here is the evidence:
- One hectare of land can support up to 7 million worms, which together weigh 2.4 tonnes. In favourable conditions, they can turn over around 50 tonnes of soil per hectare each year, enough to form a new layer of topsoil 5 mm deep. It has been reported that in one trial, worms built an 18-cm-thick topsoil layer in 30 years.
- Earthworm burrows aerate the soil and allow water to drain up to 10 times faster than in soils without earthworms. Uncultivated soils with high populations of earthworms have up to 6 times greater water infiltration than cultivated soils, which reduce earthworm populations.
- Worms help plants grow better – worm castings are richer in nutrients than the surrounding soil, with phosphorus levels four times higher and readily available nitrogen. Their burrows allow plant roots to reach deeper into the soil to access more water and nutrients. In addition, the burrows contain nutrient-rich worm castings.
- Earthworms improve soil fertility. In research conducted in New Zealand and Tasmania, the introduction of earthworms into perennial pastures (where there were no earthworms previously) initially increased pasture growth by 70–80% and by 25% over the long term. Research in the Netherlands showed a 20% increase in pasture growth, and in Ireland increases of 10% were observed. In wheat production research conducted by the CSIRO in Adelaide, glasshouse trials showed an increase of 35%, while paddock trials showed increases between 13% and 75%. (Sources: NSW Department of Primary Industries – “How earthworms can help your soil”, Department of Environment & Primary Industries Victoria – “Worm Wise II”)
This clearly shows us that earthworms can dig far more soil than we can, and they do it in a much more efficient manner. Even more so, they can dig soil in a way that produces many additional benefits. When we dig the soil, we damage it! That should be enough to convince us that it’s best to let the worms do their job, and that it’s in our benefit to build no-dig gardens. So without any further ado, let’s look at what no-dig gardening is all about.
The Technique of No-Dig Gardening Explained
In 1977, Esther Dean, an Australian gardener and author, pioneered the technique commonly referred to as “no dig gardening” with the publishing of her book “No-Dig Gardening and Leaves of Life”. Since that time, countless no-dig gardens have been built worldwide and the technique is thoroughly time-proven and tested. It has proven to be an immensely productive way to grow all manner of trees and plants. In the US, no-dig gardening is often referred to as lasagna gardening.
There are many ways to build a “no-dig garden”, but they all share the same underlying principle, which is soil building. No-dig gardens can be constructed anywhere because this technique creates soil – a rich, dark, healthy, nutrient-filled humus that plants love. They can be built over soil, an existing lawn, or concrete.
As a brief description, no-dig gardening works by laying down different organic materials such as pea straw, lucerne, animal manure, finely chopped prunings, kitchen scraps, and compost in layers over each other to create what is essentially a thick, flat composting system that fills a garden bed. To plant seedlings or plants into such a garden bed, small ‘pockets’ or holes are made that hold as much compost as a small pot you could grow the plant in. They are then filled with compost, and the plants are planted into them. It’s really simple, and the results are incredible. Essentially, the no-dig garden is constructed of alternating layers of carbon-rich and nitrogen-rich materials, just like a properly made compost heap.
This diagram shows how a no-dig garden bed is typically built:
How to Build a No-Dig Garden in Ten Easy Steps
Building a no-dig garden is a very simple technique that doesn’t take very long. I have taught no-dig gardening classes where students get to build a no-dig garden for the first time ever, and a small group can easily construct and fully plant up a 1m x 4m (3’ x 12’) no-dig garden in around 30 minutes.
There are two main construction methods for building a no-dig garden:
- No dig gardens built on concrete, paved areas or rocky ground.
- No dig gardens built on existing garden beds or lawns.
The only difference is that you need to add an extra layer first when building on hard or rocky surfaces.
Here are the step-by step instructions for building a no-dig garden:
Step 1 – Select and Mark Location
- Select a suitable location to construct a no-dig garden bed. Ideally, it should be on a fairly level surface and receive 5 hours or more of sunlight each day. You can build the no-dig garden over any surface, including existing soil, lawn, concrete or paving – the first step of the construction will vary depending on the surface.
- Either mark out where the no-dig garden bed will be and build it without ‘sides’ or edging, or construct a raised garden bed.
Step 2 – Gather Materials
You will need the following materials:
- Newspapers or cardboard
- Animal manure or organic fertilizer
- Straw bales or lucerne (alfalfa hay) bales or both
- Compost
Optional materials:
- Kitchen scraps, worm castings, rock dust
If building on hard or rocky ground, you’ll also need:
- dry small sticks and branches, old dry leaves
- dry seaweed (optional)
You will also need the following items:
- If using cardboard – Bucket of water for soaking cardboard
- Watering can or hose for watering
Step 3 – Preparing the Ground
- If building over an existing garden bed or soil, no further preparation is required.
- If building over concrete, paving, rocky ground or other hard surfaces, first lay a 7-10 cm (3”-4”) layer of small sticks and branches, twigs and old dry leaves. This layer improves drainage, preventing water from pooling on the hard surface and creating waterlogged soil. You can also add dried seaweed (if you can get it) to this layer.
- If building over lawn or grass, you can mow the grass very low first, or just leave it. Next, fertilise it with plenty of nitrogen-rich fertiliser (such as blood & bone or manure) and lime, then water it in. The fertiliser will help the grass break down once it is covered and buried under all the layers that will go on top of it.
Step 4 – Lay down Newspaper
- Lay down sheets of newspaper in layers approximately 0.5cm thick (approx. 1/4” thick), and overlap the edges by 10-15cm to prevent grass or weeds growing through.
- Using a watering can or hose, water the newspaper well.
This newspaper layer will retain moisture and serve as a weed barrier. It will gradually break down over time.
If using cardboard, you will need to pre-soak it in a bucket of water first, which is not as easy. Another issue with cardboard is that it contains glue made from borax, so it’s really a second choice.
Use newspapers if they are available, and more importantly, do not use glossy printed paper or office paper, as they contain toxic inks and bleaches, something you don’t want going into your food!
Step 5 – Lay down Lucerne
- Lay down a layer of lucerne approximately 10cm (4”) thick over the newspaper.
- Using a watering can or hose, water in well.
You can use any other carbon-rich material like peas straw, hay, or sugar cane mulch, but lucerne is preferred because it has a higher nitrogen content and decomposes more easily. The carbon-to-nitrogen ratio (C:N) for lucerne (alfalfa hay) is 18:1, whereas for straw, it is 80:1.
Step 6 – First Manure & Compost Layer
- Sprinkle a thin layer of manure. You can also add compost to create a layer 5cm (2”) thick.
- Using a watering can or hose, water in well.
NOTE: If you want to add other ingredients such as kitchen scraps, worm castings, or rock dust to your no-dig garden, this is the layer to add them to. Just use a thin layer; don’t overdo it! The worm castings and rock dust can also be used in the higher layers, but kitchen scraps need to be placed in this lower layer only to keep them well buried. This prevents vermin such as rats and mice from digging them up.
Step 7 – First Straw Layer
- Lay down a layer of straw approximately 10cm (4”) thick over the layer of manure or manure/compost.
- Using a watering can or hose, water in well.
You can use any carbon-containing material here, such as pea straw, hay, sugar cane mulch, etc.
Step 8 – Second Manure & Compost Layer
- Sprinkle a thin layer of manure. You can also add compost to create a layer 5cm (2”) thick.
- Using a watering can or hose, water in well.
NOTE: If you want to add other ingredients, such as worm castings or rock dust, to your no-dig garden, you can also add them to this layer.
Step 9 – Second Straw Layer
- Lay down another layer of straw approximately 10cm (4”) thick over the layer of manure or manure/compost.
- Using a watering can or hose, water in well.
You can use any carbon-containing material, such as pea straw, hay, sugar cane mulch, etc., here.
Step 10 – Make Pockets of Compost in Top Layer and Plant Up
- Make holes in the top layer of straw approximately 10-15cm (4-6”) wide, and equally deep.
- Fill with compost.
- Plant seeds, seedlings or plants.
- Using a watering can or hose, water in well.
You can also add seaweed extract to the water when you water the seeds, seedlings, or plants. Plants need more than the basic NPK (nitrogen, phosphorus, potassium) in chemical fertilisers. Seaweed contains nearly every beneficial mineral, including all the trace elements that plants need, and it really helps your plants develop strong, healthy roots.
Now that you’ve finished, step back and admire your newly constructed no-dig garden bed! It’s that easy, and that’s how you build it in 10 simple steps!
There Are Many Approaches to No-Dig Gardening
The steps above outline just one of the many no-dig gardening ‘formulas’. There are many ways to build no-dig gardens, and many recipes for what to use in each layer. Some no-dig gardens can be very high and freestanding, while others can be low. They all work because they use the magic natural formula we also use in composting, alternating layers of carbon-rich and nitrogen-rich materials.
So far, we’ve only discussed building no-dig gardens to create new garden beds, but the beauty of this system is that you can also convert existing garden beds to a no-dig system, and it’s even easier.
How to Convert an Existing Garden to a No-Dig Garden
Building new gardens from scratch is one thing, but it doesn’t happen very often. More often, we encounter a tired, run-down garden bed with depleted, compacted soil, where little grows other than weeds. It’s even easier to ‘retrofit’ an existing garden, to renovate it and convert it into a no-dig garden.
You can even use this technique to transform a fully planted garden bed into a no-dig garden by simply laying down a two-layer mulch!
Converting an existing garden bed to a no-dig system involves three key steps:
Step 1 – Prepare the Soil
If necessary, loosen compacted soil. If the soil is not compacted, go to Step 2.
You can loosen compacted soil manually with a garden fork, which takes a few minutes, or you can plant ‘green manure’ plants with deep tap roots, which will drill into the compacted soil and break it up. This will take much longer (a few months!) as the plant grows through its growing season. Once the plant starts to flower, it is cut down and the soil level and dropped on the soil surface, with the roots left in the ground – this is “chop & drop”. The roots will then break down and create deep air and water channels, and the soil will be loosened naturally.
- Cool Season ‘green manure’ plants which have deep taproots that can be used to break up compacted soil – Fenugreek, Lupins, Woolly Pod vetch
- Warm Season ‘green manure’ plants which have deep taproots that can be used to break up compacted soil – Lucerne
The most important thing to do is to give an old garden bed a head start. Once the soil is loosened, it will never be compacted again, because you don’t step in a no-dig garden!!!
To loosen compacted soil, break it up with a garden fork, but don’t turn it over – we’re just trying to make the soil loose and friable here, not to kill all the soil ecology, which is what turning the soil does in conventional gardening and why it’s done!
Once the soil is loosened and the no-dig garden layers are added, they will start to break down, adding organic matter to the soil. The earthworms will do all the digging from there on, taking the organic matter from the surface and carrying it further into the soil, slowly converting the soil underneath into a rich, dark humus – real soil! Remember, humans don’t dig; earthworms do, and they do a much better job than us. So leave the digging to the experts, the earthworms, and save your time and energy!
Step 2 – Lay down Manure & Compost
- Sprinkle a thin layer of manure. You can also add compost to create a layer up to 5 cm (2”) thick, but a thinner layer is just fine.
If there are existing plants in the garden bed, keep the materials away from the stems/trunks to avoid ‘collar rot’ – rotting the base of the plant.
You can also add other ingredients such as worm castings (a rich fertiliser filled with lots of beneficial soil organisms) or rock dust (a slow-release source of trace elements and minerals) into this layer. - Using a watering can or hose, water in well.
You can add seaweed extract to the water; it’s rich in potassium, which helps fruiting and flowering, and is loaded with lots of minerals that help the plants develop a strong and healthy root system.
Step 3 – Lay down Straw
- Lay down a layer of straw approximately 10 cm (4”) thick over the layer of manure or manure/compost.
If there are existing plants in the garden bed, keep the mulch away from the stems or trunks to avoid ‘collar rot’ – rotting at the base of the plant. - Using a watering can or hose, water in well. You can use seaweed extract with the water again.
You can use any carbon-containing material here, such as pea straw, hay, sugar cane mulch, etc.
So, in 3 easy steps, you’ve converted your existing garden into a no-dig system.
Make sure you don’t step in the garden and compact the soil again. Use paths – garden beds are for plants, paths are for humans! Remember, you and the plants have conflicting needs. They need soft, loose, friable soil they can easily sink their roots into, while you want firm, stable paths you can walk across without sinking into!
How to Maintain a No-Dig Garden from Season to Season
It’s really easy to maintain a no-dig garden. It’s a quick twice-a-year task!
At the start of spring or autumn, after the previous season’s crops have been harvested and the layers of material on the soil surface have rotted down, it’s time to add new material to replenish the layers of the no-dig garden.
To replenish the layers of the no-dig garden at the start of spring and autumn:
- Add a layer of manure as before (and compost if you wish, which is optional).
- Cover the manure/compost layer with a straw layer
- Water it in
That’s all you need to do until the next growing season! Quite simple, really!
In conclusion, with no-dig gardening, you can reduce your effort and time in the garden, save energy and water, maintain a healthy soil ecology, and let Nature do the work. It’s how Nature does it, and it’s the most sustainable way to garden!