No Dig Vegetable Gardening
7th November 2012
Charles Dowding has been growing organic vegetables for thirty years, always in a no dig way, in different gardens and countries. From 1998-2012 he cropped an intensive acre of surface composted beds in Somerset, principally for salad leaves as well as a wide range of vegetables, sold in local shops and restaurants. He has written four books on vegetable growing, writes articles for several gardening publications, gives talks, and runs courses, see www.charlesdowding.co.uk . Here he explains what 'no dig' gardening is, how to do it, and what the benefits are.
Because so many gardeners are used to digging their soil every year, they wonder how it can be possible not to, and I offer answers here to some commonly asked questions.
What does ‘no dig’ mean?
Two main things, no soil disturbance and encouraging soil life. You need never move a tool through the soil, except if you need to hoe. Spread a thin mulch of compost every year to provide food for worms and other soil life, helping them to maintain air channels and a good structure. My experience of thirty years has revealed how plants love to grow in undisturbed soil, even dense clay, whose surface is always dark and crumbly.
Is the first year the hardest with no dig?
Yes the first year needs most input, and things become easier after that. Initially some digging of large perennial roots may be required, such as docks, brambles and woody plants. If the soil is full of long lived perennial weeds such as couch grass and bindweed, you can mulch for a year with black plastic, perhaps growing a few large plants through it such as courgettes.
In the first year only of vegetable growing, I spread 6-12cm of compost/manure to help worms improve soil structure and raise fertility. I suggest when starting no dig that you begin with one or two beds and experiment to find your favourite methods. It may seem strange at first, planting into compost on top of undisturbed soil, but the rewards are huge, especially the reduction in weed growth.
How do you prepare soil for sowing?
Each autumn I spread 2-3cm of garden compost or animal manure, after clearing last year’s plants and any weeds. Frosts then break up the lumps and by spring the surface is soft and dark, excellent for sowing and planting. Rake very lightly before sowing, to smooth out the surface of slightly raised beds, for which a good width is 1.2m wide and with no wooden sides, to reduce slug habitat. Pathways of 0.5m mean that you need compost for about two thirds of the growing area.
How to create and maintain pathways?
Bare soil is best, to have less slugs and allow vegetables to root into pathways, which you can weed and hoe just like the beds. This is made easier by spreading about 3cm of rough compost on paths in the first year only. Also there is always a little compost falling from beds onto the paths and that is fine because path soil needs feeding too.
Why switch to no dig?
My experiments suggest that dug soil needs time to heal. Most scientists are only recently discovering about the life and structure of soil, how it is a delicate living organism which responds bountifully to correct care and feeding. Professor Elaine Ingham in the USA has pioneered many new understandings.
In different gardens over three decades I grow superbly healthy and high yielding plants with less addition of nutrients than is sometimes recommended – for instance, I do not feed tomatoes in the polytunnel (yet they yield well), I never use fertilisers, even organic ones, and I think the ever increasing amounts of soil life are mobilising the soil’s previously undeveloped potential, by maintaining an open structure for roots to travel in, and then helping those roots to find what they need, when they need it.
Do you recommend thick mulches?
For growing most vegetables I use just the thin mulch of compost, but mulching also depends on the climate, weeds and on what you want to sow or plant. Thicker mulches of partly rotted organic matter are good for dry conditions and for smothering abundant weed growth in just the first year of no dig, also for mulching soft fruit bushes and large vegetable plants such as courgette.
Doesn't soil have to be turned every three or four years to increase air and reduce weeds?
No way. My longest run of no dig was fifteen years and best growth was at the end, in the difficult weather of 2012. When soil inhabitants are fed, they can build an enduring structure which is aerated but firm: for instance one can walk on beds if need arises, and push wheelbarrow loads of compost on the permanent paths of soil. Yet roots such as carrot and parsnip go down happily.
Keeping weed free is easier than you may imagine because weeds germinate less in undisturbed soil, and are easy to hoe or pull out of the soft, compost-fed surface. Regularly pull the few small weeds you see so that none ever set seed, resulting in clean soil and almost no weed seeds in the compost heap. In early spring there is often a small flush of weed seeds germinating from their winter dormancy, and from composts or manures, and a light hoeing is often needed in April.
Do you need fertiliser in no-dig gardening?
No dig allows the soil food web to remain active, so less nutrients need to be added, except where you know of mineral deficiencies. The only mineral additions I make are occasional dust from volcanic basalt, and seaweed, because I have a feeling that many soils are low on trace elements and therefore benefit from small additions of these intensely rich soil foods. Adding them to compost heaps or animal litter is another way of increasing soil health.
Is no dig gardening a new practice?
No dig has been practised forever, yet has never caught on generally. I am unsure why, but have noticed that it is difficult to be ‘different’! However I am now finding a rapidly growing interest in my work, through books, the talks I give and courses I run, and from successes enjoyed by gardeners when they stop digging. My website www.charlesdowding.co.uk is full of advice on many topics, including six years’ results from my experiment of four beds 1.5x2.5m, comparing growth of the same vegetables between the two dug beds and the two undug beds.
What has the experiment revealed so far?
Total harvests are similar from the dug and undug beds, but there are also some fascinating differences. Vegetables grow faster in spring on the undug beds, especially onions and spinach, while there are more weeds on the dug beds. Parsnips root better into the undug soil and potatoes are the only vegetable to prefer the loose, dug soil. Slug damage is more evident on the dug beds, I think because they like the smooth surface of clay soil to slither over, compared to the rougher surface of compost on undug beds. And when watering, water runs more easily into the undug soil.
Images above show 'no dig' gardens. Copyright; Charles Dowding.
BOOKS BY CHARLES DOWDING