Introduction to No Dig

No dig works in varied climates and conditions. It’s always the same principle of encouraging soil life, just the techniques may differ. For those of you in dry climates who may be wondering whether to mulch with hay or straw as opposed to compost, here is the view of the horticulture editor of ABC Gardening Australia 06/08/18:

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One third of my no dig garden at Lower Farm, 2008, on clay soil which until 1999 was compacted by heavy machinery

It’s much more fun mulching with compost instead of undecomposed material. I love the clean finish and it’s far less bulky than piling up a range of undecomposed materials on the beds. The surface is more workable and it feels luxurious to be planting into a generous layer of pure compost. I’ve been spreading my homemade compost first and topping it off with the compost I pick up from my local council at around £17 per tonne, such a fabulous resource.

Phil Dudman
ABC Gardening Australia

Most soil already has a good structure for plant roots to grow, and is full of growth-enabling organisms. Millions of fungal threads, nematodes and earthworms, to name a few, are being helpful right under our feet, mostly out of sight. We need to help them to help us.

You have already started no dig without knowing! Since the last time you dug or tilled or forked your soil, it has been healing itself, with networks of fungi, breeding of health-bringing organisms and recreation of a stable structure. Your task is to build on that, to enable good structure and drainage, plus you will discover some extra benefits.

On a farm scale, no dig is called no till. Farmers converting from cultivation to no till find that years one and two can be difficult, with lower yields as the soil organisms and structure recover. Thereafter the benefits are very positive – see this study, and the work of John & Alex Cherry who run Groundswell Festival in Herts, every June.

You can hear about how I became a no dig grower from 1982, on this podcast by Jesse Frost of No Till Growers in the USA.

Why no dig is so successful

Some rain would do miracles… but not as amazing as the no-dig miracle. Thank you for all your teachings and inspiration! We eat so much thanks to you!

Dita in north Poland
Blog Reader
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August 2015, after clearing onions I am about to plant autumn salads, no weeding, few slugs, no compost since the previous autumn: it’s rapid

The main bonus for gardeners and farmers whose time is so precious, is that weeds germinate less.

because organic matter on the surface (instead of dug in) is a weed suppressing mulch, both physically and through encouragement of fungi near the surface – see the work of Elaine Ingham

because undisturbed soil does not need to recover: just as disturbed people need to recover, so does disturbed soil, and it achieves that through what we call weeds.

because their seeds are not exposed to light during cultivation

As well as needing to weed less, the few weeds you need to pull will come out easily, or hoeing is easy in the soft surface.

No Dig Advantages

Mycorrhizal fungi stay intact so can help plant roots to find more nutrients and extract more moisture, because they are smaller than roots and can reach into tiny crevices.

You can be in the garden during wet weather because drainage is good: the soil’s structure has not been broken by tools or machinery, water runs through and mud does not stick to your boots! This was emphasised to me by a Scottish farmer: “It always rains in Scotland, but I can be in my no dig garden with clean boots in any month of the year”.

It’s easy to resow or replant at any time of year, quickly and with no soil preparation needed. Simply twist out plants when you clear a preceding crop to leave most roots in the soil, remove any surface debris, and pop in the new seeds or plants.

Moisture is retained and is available to considerable depth, because there is no ‘shatter zone’ caused by cultivations.

Warmth is retained by soil in winter because deep-level warmth can rise, unhindered by damage from cultivations: my gardens have always been admired for their early harvests.

Carbon stays in the soil rather than being converted to CO2 by oxidation after cultivations.

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Article by veteran gardener Jim McColl in the Aberdeen Press and Journal, November 2017. After being sceptical, Jim is now impressed with the potential of no dig.
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The Edibles Garden team March 2018 in front of their dig/no dig comparison beds, year one. Most of the rest of this garden are no dig, worth a visit.

In spring 2018 I was invited to Beechgrove garden near Aberdeen in NE Scotland, not the easiest climate, where BBC Scotland run a garden of many facets. The experience of Jim McColl and George Paterson, plus input from Chris Beardshaw, mean there is plenty to show on every programme. They are running a did/no dig trial, where Jim interviewed me for the programme on 10th May 2018. I had this feedback from a viewer, Robert Hine by email:

Congratulations on your recent visit to Beechgrove. Succinct, to the point, punchy. A brilliant interview with a simple message, well delivered.

Robert Hine
Programme Viewer

Rapid uptake by prominent gardeners

Many gardening organisations are now trialling no dig, after seeing it’s potential:

  • The RHS at Wisley in Surrey, worth a visit with a new garden project opening 2020. Sheila Das the gardens manager first heard of no dig at a talk I gave at Kew Gardens in 2011. This is her feedback August 2018:
    “I am really pleased with our veg garden and student plots this year. I haven’t seen the Wisley veg garden looking as abundant in years.”
  • The National Trust is no dig at many of its gardens and especially those producing vegetables, such as Sissinghurst, where I was employed as consultant in 2012/13, to reduce the garden acreage and make it profitable.
  • Kew Gardens in London, where the kitchen garden is no dig since 2016.
  • Ballymaloe Cookery School near Cork in Ireland, growing food for the students on 3 acres and noticing huge labour savings from reduced weed growth.

A prominent soil scientist, Elaine Ingham in the USA, has spent her life researching the biology of soil, which is key to understanding the benefits of no dig. She refers to the Soil Food Web, and here is a nice summary of soil biology, by one of her students.

A good book to read as background to these understandings is Teaming with Microbes (Timber Press 2006) by Jeff Lowenfels and Wayne Lewis.

Garden Size

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The no dig bed of my trial 28th April 2018, spring plantings starting to grow
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Same bed 4th August 2018, all veg except the onions are second plantings after 43kg/95lb harvests already taken

No dig works on any scale, even a single bed as above.

My market gardens have ranged in size and style, and I was cropping 11 acres /4.4ha in the 1980s, with four apprentice helpers. The beds received just a half inch of compost per year, but I was also adding organic matter to the paths (straw), and was cropping less intensively than now.

Homeacres has just a quarter acre/1000m2 of beds, mulched with up to 2in/5cm compost every year, once a year, and cropped often twice a year. We harvest year-round salad leaves and a wide range of vegetables, sold in local shops and restaurants. The garden grows trials too, such as comparing the effect on plant growth of dig and no dig.

Learning from Comparative Trials

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Trial beds, the no dig one is closest, dug bed behind and both have the same amount of compost, 21st May 2018 with lettuce being harvested already

Since 2007 I have been recording growth and harvests in dig and no dig beds, surface area 7.5 square metres each. Total harvests 2007-2017 are 863.95kg dig, and 923.42kg no dig. In nine years out of eleven, the no dig was higher yielding. Find details of this trial, under the Learn banner.

Often there is not a huge difference in growth, but a common variation is stronger growth in early spring on no dig. In a cold spring such as 2018 this was especially marked, that seedlings preferred starting life in surface compost, compared to sticky soil in which the compost was incorporated while digging, so roots take time to access it. Plus the soil structure was damaged by digging.

Furthermore in spring 2018 there was more slug and wireworm damage on the dig bed, which contradicts the common assertion that “digging allows birds to eat pests”. What should also be mentioned is that digging allows birds to eat worms, and disrupts the natural balance of pest and predator, for example disturbing beetles that eat slugs.

Generally I notice more slug damage on the dig bed, compared to the no dig one. I wish there were more research on this because, from what I can find, we need more understanding about how soil organisms interact.

I just had to let you know how Amazing my Garden is doing, it is doing so well, too well almost. It is so abundant I can hardly keep up. I did exactly what you said No Dig Mushroom compost on top and planted. It had done so well, Thankyou. I have told the people that said No you can’t do that how good it is and the guy who delivered the Compost is Amazed. I have given everyone your Website details. Thanks Charles, your Amazing!!

Rachel
New Patch Forum Participant

No Dig on Clay

It’s often claimed that you can’t start no dig on clay soil, without digging or even double digging. This is not true.

At Lower Farm, Shepton Montague, Somerset in 1999, I took over a third acre of clay soil which had been compacted in wet weather by heavy machines. There were putrefying lumps of grey and airless soil, whose surface was sticky in winter and hard in summer. Gradually my mulches changed it to brown, healthy clay as soil life multiplied and created a structure, without any cultivations.

I cleared the weeds by hand and surface mulched with only 3-4cm compost which was18 month old horse manure. In the first year, crops were below average as the soil was recovering. But in the second year there was good growth; for example parsnips grew deep and long into the still dense clay, which was becoming more aerated by soil life.

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This clay soil at Lower Farm had been compacted by machinery in 1998/9. Then I surface mulched only, with compost, and soil life gradually recreated an aerated structure. This is September 2010.
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View of vegetables growing in this same clay soil, no dig for 11 years, September 2010
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Grown in this clay soil, March 2011 I needed a spade to lever out these parsnips, sown a year earlier in the compost mulch, then they descend without forking into the soil below.

Every autumn I spread another 3-4cm compost and from year three onwards my vegetables were abundant. Furthermore weeds were few and easy to pull or hoe, in a surface which stayed soft in dry weather and was not sticky in winter.

My conclusion is that feeding earthworms and other soil organisms from above allows them to recreate a damaged structure, over time.

A rare exception is soils where a true hard-pan has developed, such that growth and drainage are awful. In this case a one-time dig or forking is worthwhile, before adding on top.

Incidentally, what is sometimes referred to as “compaction” is just soil’s natural firmness, which is good! Plants like rooting into firm soil; if soil is too loose, they fall over and moisture is lost.

Virtues of compost

Compost is not ‘fertiliser’ in the common sense of the word: it is soil food and holds nutrients in water-insoluble form. Therefore you can spread compost even in autumn, even though it is washed through by rain before plant roots have access to it. My gardens boast abundant growth a year after spreading compost mulches: this would not be the case if nutrients leached away.

There is no need to spread more compost after clearing crops in summer! Simply sow or plant the next vegetables and flowers, because there is goodness in the soil waiting to feed them.

To maintain fertility, simply spread an inch or two of homemade compost, or composted animal manure, or purchased compost every autumn ideally, or you can spread compost at any time of year, spring is good too. The compost is a mulch that protects soil. Winter weather in particular, breaks its lumps into softer pieces by spring, with some help from light passage of a rake. Rain can wash through and nutrients are held, in water-insoluble form, until fungi help plants to feed on them.

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Charles spreading compost (2 year old cow manure in this case) in cold December weather, Lower Farm 2010
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Charles spreads homemade compost in May 2011, after clearing spring cabbage, with garlic behind, Lower Farm

Compost is the best mulch in damp climates such as the UK, because it does not offer habitat to slugs. Avoid mulching with straw or hay. Paths can have mulches of half-decomposed and small pieces of wood, but do be wary of offering slug habitat.

Nutrients become available when needed by plants, through a combination of

  • air and soil temperatures being high enough for plant photosynthesis/metabolism, which causes roots to signal fungi with requests for food, and moisture too
  • fungi in compost and soil, mainly mycorrhizae, which are able to find nutrients (and moisture) for roots.

Chemical fertilisers are a risky and polluting way to feed plants because they are mostly water soluble, damage soil fungi, and may be leached out by rain before plants can use them all.

No dig: grow soil and plants

Save time and effort by helping natural processes to work with you. No dig allows soil to develop its own aerated structure, so vegetables and flowers grow more easily. Weeds grow less because undisturbed soil does not need to recover: I say that from 35 years of no dig experience.

  • Fertility building from on top is a copy of natural processes, where organic matter always lands on top. Worms and soil fauna travel upwards to find the food.
  • As soil life increases, the soil becomes better aerated. A better result more quickly, and without the disadvantages of digging such as loss of moisture & structure, damage to soil life including worms and fungi, extra weeds growing after digging, expense of time and labour.
  • The soil surface, even on sticky clay, becomes darker and crumbly, with a consistently good tilth of fine yet stable soil crumbs. It’s easy to hoe (if needed) or pull weeds from, and needs less water.
  • Throughout the soil, there is a proliferation of beneficial bacteria and fungi such as mycorrhizae. They help plant roots to find nutrients and moisture, which may often have been present already, but sometimes remain unavailable to roots if biological activity is low. Fungi love wood especially so small wood in the pathways is worthwhile, say 2cm/1in layer, apply before winter if possible.
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12th December 2017, Homeacres West side and most beds mulched with compost
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12th December 2017, main garden Homeacres where we trialled wood shavings in the paths to add organic matter and feed soil life

After a year or so of no dig, your beds have a more stable soil structure and with better drainage than if you were regularly loosening them. You can even walk on them when needed. Occasionally to take a short cut I push a heavy wheelbarrow across my beds and there is no sinking in, or ill effect.

It’s so heartening to consider all the benefits for soil life. For example, fungi are mostly invisible and less obvious than earthworms, but Claire Lassman, biologist from Frome, Somerset writes: “I come from a mycorrhizal background and no dig makes complete sense, because plants can simply ‘plug in’ to an established soil network, with immediate access to nutrients rather than having to start anew”.

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4th June 2017, no dig bed on left and dig bed on right
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Five years of harvests from the two trial beds, dig bed is dug every December to 9in/22cm

My dig/no dig experiments at Homeacres and Lower Farm show that most vegetables grow more strongly and healthily on the no dig beds, for less effort and time needed. The no dig bed on right needs four hours less per year than it’s neighbouring dug bed.

The quality of harvests is sometimes different, for example the root vegetables from undug soil come out cleaner, and I see less slug damage to the no dig vegetables.

In summary, no dig/no till saves time, gives bigger harvests, is ecologically beneficial and keeps carbon in the soil.

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Part of my Homeacres garden August 2017, easy to plant and maintain, almost no weeding needed, paths are mulched and weed free with no wooden sides for the beds

So is No Dig Easy?

Yes, because you can grow the same amount of food in a smaller space, and with less time needed for weeding. No dig can be practiced without spreading much organic matter, but some on the surface is good. An annual dressing of compost accelerates the improvement in soil structure, and is particularly worthwhile for growing good vegetables.

In dry climates the surface mulch can be straw, hay, grass and any undecomposed organic matter. In climates where slugs are prevalent, compost works best.

In temperate climates, all that soil needs is a cover of compost, to maintain it’s life and enable plants to feed. Adding compost is as much about enabling soil to mobilise it’s resources, as about adding new nutrients. Compost is not ‘fertiliser’ in the common sense of the word: it is soil food.

Hence there is no need to spread more compost after clearing crops in summer! Simply sow or plant the next vegetables/flowers, there is goodness in the soil waiting to feed them.

Spread an inch or two of homemade compost, or composted animal manure, or purchased compost every autumn ideally, but you can spread compost at any time of year. The compost is a mulch that protects soil. Winter weather breaks its lumps into softer pieces by spring, with some help from light passage of a rake.

If the benefits of no dig growing appeal to you then carry on reading to find out how to get started.