The no-dig method of gardening, dishes out big promises. Less digging, less weeding, higher yields and healthier vegetables. The success lies in maintaining the quality and structure of the soil, by regularly mulching the top layer to leave lower layers undisturbed, which allows beneficial organisms and fungi to flourish.
The king of no-dig is Charles Dowding. He has been trailing the method at his organic garden in Somerset for decades and has seen it work miracles on his crops. Here Charles explains the principals and benefits of no-dig gardening in more detail.
Why no digging?
So much that happens in the soil is invisible, and can work for us if we allow it by minimising soil disturbance and feeding soil workers with organic matter. This results in a soil that is structured rather than loose and crumbly: roots can penetrate but also find anchorage, and flourishing populations of micro-organisms help to supply nutrients. Weeds tend to grow less and are more easily removed.
Two features stand out in three years of comparisons between vegetables grown in dug and undug soils. Firstly, spring growth is stronger and healthier in the undug beds, whereas the dug beds tend to catch up in autumn. This suggests that soil needs time to recover from being disturbed by digging. Secondly, the main vegetables that grow bigger on dug soil are brassicas, whose roots do not use mycorrhizal associations to help them forage for nutrients. This supports the important point that soil cultivation is damaging to soil fungi, mycorrhizae above all.
No-dig exponent Charles Dowding pulls leeks from his intensively cropped, organic vegetable garden in Somerset.
In my own garden I grow vegetables and ornamentals on two-and-a-half acres of clay soil that has not been dug or loosened in any way for up to 12 years. Some of it was compacted, airless and blue with clay when I took it on. My approach is simply to surface-mulch with compost and composted manure: the results are good and it is always especially impressive to see the long, straight growth of root vegetables such as parsnips and carrots.
How no-dig reduces weeds
Under the no-dig method, weed seeds are less inclined to germinate. If my two acres grew a normal amount of weeds, I would soon be out of business. Undug, surface-composted soil grows few weeds, which I explain in terms of recovery. Soil is firstly re-covering its surface, physically, and secondly this new green carpet helps the recovery in the sense of healing from a trauma, after the damage caused by cultivation. For example, one often sees a carpet of green seedlings after rotavation.
Perennial weeds can be weakened and sometimes eliminated by mulching to exclude all light, most effective in the growing season. I find that two applications of cardboard for ten weeks each will (say starting in March) kills all annual weeds, creeping buttercup, nearly all dandelions and all grasses except for couch, which needs either another four to six weeks cover or careful extraction with a trowel. Mulching with compost as well helps to bring any remaining perennial roots up closer to the surface, easier to pull or extract, although bindweed needs persistent removal to weaken its far reaching roots.
Benefits of adding organic matter
Adding organic matter, like well-rotted manure to the surface of growing beds, encourages organisms that contribute to soil structure and fertility.
- Instead of disturbing soil, add organic matter to its surface, to encourage the organisms that contribute to soil structure and fertility.
- Impoverished and thin soils draw major benefit from thick mulches (10cm-15cm) of well-rotted organic matter. This improves moisture retention and reduces weeding.
- Have organic matter on the surface for most of the year, to protect and enrich soil.
- All composts are effective but animal manures are best for nutrient shortages.
- Annual applications of 2.5cm-5cm organic matter on the surface will improve soil fertility and structure, reducing the need for synthetic fertilisers and herbicides, which are not helpful to soil life.
Charles Dowding is the author of Organic Gardening the Natural, No-Dig Way, Green Books, 2010 (second edition). You can find out more about the no-dig method at Charles’ website.