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No dig growing
Many gardeners are discovering the benefits of growing healthy food without any soil cultivation. As well as saving the effort of digging, rotovating, 'forking through' or whatever, you will find that weeds eventually grow much less, that vegetables grow just as well, or better, and that soil sticks less to your boots - which may seem a small point but it makes a big difference to the pleasure of being out in the plot.
Here is a comment from Mark Burge, gardener at Barnsley House in Gloucestershire:
"No matter how many photos you see, nothing can compare with the real thing, it was amazing to see your veg 'zinging' with health and vitality and no weeds in sight, although you did manage to find one hiding in amongst your brassicas."
The first step depends on the weeds you have, and how much organic matter you can use. Below I show a process of patient mulching, to clean soil of existing weed growth and to either smother or exhaust the reservoir of weed seeds. Once this is achieved, in 6-18 months depending on the current weed situation, gardening becomes significantly easier with less germination of new weeds.
For faster results, you can either use extra compost, up to six inches on top to smother all weed growth and then sow or plant straight into that, see stage 2 below. For an approach like this and growing potatoes at the same time, see Naomi Schillinger's blog of summer 2012 http://outofmyshed.co.uk/2012/08/13/im-never-gonna-dig-again/
Or you can do a one-off dig to remove roots of perennial weeds and bury annual weeds, leaving a surface of clean soil to sow and plant into. However, annual weeds will germinate in this soil, and extra hoeing and weeding is needed at first, see below.
- There is no need to double (or single!) dig before starting, or to incorporate manure at depth. Placing any organic matter on top is the best way to bring soil alive because that is how soil organisms work, searching for and eating organic matter at the surface, then digesting it in the soil, excreting and building a permanent structure in so doing.
- After a year or so of no dig, your beds will have a more stable soil structure than if you were regularly loosening them. From this point onwards, you can walk on them when needed. Occasionally to take a short cut I even push a heavy wheelbarrow across my beds (clay soil!) and theere is no sinking in or ill effect.
WEEDS and MAINTENANCE
After digging, soil recovers from the disruption by re-covering with weed growth. It also needs time to recover in a more general way*. By contrast when left uncultivated it has less need to re-cover and grows less weeds - but there will always be some, mostly from seeds blowing in or brought in with manures, and they need removing by hand or hoe at all times. It is a little and often approach, without a grand dig to bury all the trouble. Vegetable growing is more bountiful and much easier when weeding is just a small issue.
There are three different stages to pass through in reclaiming weedy soil for growing vegetables:
1 Initial composting and/or mulch of weedy and grassy plots. Any organic matter can be applied on top at this stage and used as a light suppressing mulch. Sheets of cardboard and/or manure, compost, leaves, grass mowings, half rotted manures and composts and so forth are all good for feeding worms which get busy under dark mulches. So soil is improving at the same time as weeds are dying off. You can also use black plastic mulches, preferably with some organic matter underneath.
manure on grass & weeds in August, paper mulch on top, but six weeks later some of the paper blew off, dandelions alive!
so more mulch (cardboard this time) is applied in September, this is Steph helping here. A problem with cardboard can be weighting it down, because under manure, as in this photo, it rots more quickly. Black plastic is easier from that point of view, and worms seem happy either way.
Here is another example, March 2013 at Homeacres where i have put two inches of well rotted compost and manure on grass, in beds three and a half feet wide, then mulched with black or green polythene or cardboard, with card in the pathways too, for an experiment to see the effects of different surface mulches. This soil has some couch grass, buttercup, cow parsley and other vigorous, perennial weeds. Keep an eye on progress in This Month.
2 Patience is key at this stage, allowing enough time for weed roots to be exhausted under whatever mulch has been used. Annuals need two to three months, many perennials take six months and up to a year for their roots to be exhausted by trying to grow in darkness. If you peel back a mulch and still find white stems of weeds, their roots are not yet exhausted.
AN EXCEPTION is when six inches or so (15cm) of manure and compost have been used to cover weeds because this is enough to prevent re-growth of all weeds (except bindweed and marestail) so you can sow and plant straightaway, see below.
LEFT same ground in June after spreading an inch or two of mushroom compost - and raspberry suckers have been planted in December, then RIGHT same ground in late August, view from other end. Little weeding needed, raspberries establishing, fine growth of four plants of winter squash
December, bed on grass made simply with manure & compost, no other mulches - and growth in May of spring vegetables
3 The third stage is normal growing, but with less weeds than one often sees on dug plots. All sowing and planting is into the dark surface layer, with plants then rooting into undisturbed soil below, which is firm but NOT COMPACT. Do bear this difference in mind at all times. Firm is good! My soil is clay and I find that all vegetables send roots into and through my walked-on, wheelbarrowed-on pathways of dense, firm but not compacted soil. Undisturbed soil develops and maintains a honeycomb stucture of small air passages, especially when it is fed annually with an inch or so of compost on top. Compost can be animal manure that has been stacked for six months or more.
paths being washed with flood water in November 2011!!... and exposed roots in a pathway afterwards of endive and chard
NO DIG IS EASY?
Yes, because of not needing to dig, and having less weeds; but no dig does not mean no work! The input of time is in other ways that lead to higher fertility and less weeds. No dig can be practiced without spreading much organic matter, but an annual dressing of compost helps accelerate the improvement in soil structure and is definitely worthwhile for growing good vegetable crops.
I aim to spread an inch or two of my own compost, or composted animal manure, or purchased compost every autumn, so that winter weather can break its lumps into a tilth by spring, with some help from my rake. The organic matter is placed on beds only, about three fifths of the total area.
spreading compost in December, after harvests, on four foot wide beds - and in May after clearing winter cauliflower
Organic matter can be spread at any time of year! The most practical season is autumn, when soil is moist and still warm, so that worms can access it, and when harvests are finishing and soil is cleared of crop remains. Some ground becomes clear in spring after winter leeks, cabbages and so forth, and can be composted then if there is no remaining organic matter on the surface. I find that one composting a year is sufficient for two crops, once soil is in good heart. You can tell this by how healthy and vibrant your vegetables are looking.
Where to find the organic matter you need? Compost is becoming more available, and often cheaper, thanks to recycling of green waste, and there are surplus quantities of animal manure to be found in many localities, in addition to any compost you can make.
WHY NO DIG
- No-Dig, with compost spread annually on the surface, makes soil more fertile, plants more healthy and helps reduce weed problems
- Fertility building from compost and manure on top is a copy of natural processes (forest floor, animal excretion on pastures) and works really well for vegetable growing.
- Worms and soil fauna are encouraged, then as they increase the soil becomes better aerated, without the disadvantages of digging (loss of moisture & tilth, extra weeds, expense of time and labour).
- In time, the soil surface, even on sticky clay, becomes darker and crumbly with a consistently good tilth of fine but stable soil crumbs.
- Throughout the soil, there is a proliferation of beneficial fungi, such as mycorrhizae, and bacteria. These help plant roots to find the nutrients they need, which may often be present already, but can remain unavailable to roots because of a lack of biological activity.
- Growth of plants in undisturbed soil with a mulch of compost is generally healthy and vigorous, and the healthy topsoil becomes easy to sow and plant into.
- Time is saved, moisture is conserved, and weed growth diminishes - once perennial weeds are removed (by initial mulching or digging) and providing annual weeds are not allowed to spread their seeds.
- I run a dig / no dig experiment (see the banner and also the archived monthly blog for December 2008 and January 2009) and find that vegetables often grow more strongly and more healthily on the un-dug beds. Total yields are similar but the quality of harvests is noticeably and intriguingly different. This photo shows the four experimental beds, of which each pair are fed the same compost/manure and cropped the same.
- In summary, soil has it’s own life and structure, it benefits us to encourage and respect it.
PHOTOS: top, drawing drills to sow carrots; bottom, my dig/no dig experiment, undug bed in front, then dug, then undug, then dug SEE ALSO under 'dig/no dig experiment' on this site
- Remember that vegetables are hungry plants and require a soil that is well structured and full of life. First year dressings of organic matter may seem a lot but will repay the effort for years to come. Until the advent of chemical fertilisers, larger amounts of compost and manure were always used than has been the case since about World War Two. Since then, more emphasis has been placed on chemical nutrients from synthetic or concentrated sources, but they cannot provide soils with food for all its myriad of inhabitants who are so necessary in growing healthy plants.
- An initial dressing of 3-6" (7-15cm) of reasonably well rotted compost and animal manure, helps kill existing weeds and lifts soil fertility to a higher level for many years.
One-off, six inch (15cm) dressings of compost in deep beds, well trodden down, are enough to kill existing grass and many perennial weeds such as buttercup, dandelion, and even small amounts of couch grass. Cardboard under the compost, in this case of a thick dressing, makes no difference as weeds are killed by the 6" of compost.
filling a new bed on grass, one half with cardboard: the six inches of organic matter in this bed was enough to kill grass, dandelions and buttercups same bed, harvest of carrots in late July
- AVERAGE AMOUNTS OF COMPOST USED ANNUALLY are one to two inches and this on beds only. Using less compost is possible but creates more work through weeds growing in impoverished soil, less healthy growth and smaller harvests
- Soil which has enduring perennials such as couch, bindweed and marestail will require a year of light-excluding mulch such as cardboard or black polythene, preferably above a dressing of organic matter, all sitting on top of the weed growth.
- In the absence of enduring perennials, vegetables can be sown and planted into compost-rich dressings as soon as they are spread. The combination of growing plants above and increasing soil life below starts an ongoing process of soil improvement. Even root vegetables such as carrots and parsnips will find their way down, unless the soil below was seriously compacted: in such a case, it may take up to two years for worms and other organisms to develop a good structure. An initial dig would speed this up if you are in a hurry. In my garden I have always grown extremely long parsnips on heavy clay, except in the year when I took on a new patch of compacted soil. parsnips Gladiator, October 2009, were sown in well decomposed manure on top of heavy clay soil
- Sowing small seeds into clods of compost and manure is unlikely to succeed, so keep the most crumbly organic matter for your surface layer. An excellent time to spread compost is in autumn, as soon as the previous crops finish. Then there is time for frost to break up any lumps and for worms to start taking it down, leaving a fair tilth by spring. It also helps, when the surface organic matter is lumpy, if you knock it around in February or March with a fork, just on the surface, to smooth out the lumpy bits.
- Fine compost can be spread at any time of year, while lumpy compost or manure can be used in the summer as a mulch around established plants such as courgettes, or between rows of growing vegetables, even parsnips.
When plants are harvested, remove all debris to the compost heap, tread down any lumps caused by pulling rooots out, and then for any harvests before the end of August you can sow or plant again, with vegetables such as autumn salads.
a lettuce bed in May, after three pickings of outer leaves
In case you are wondering, no dig is a ‘permacultural’ approach, using compost instead of more bulky mulches of unrotted organic matter, or mulches of growing plants. The latter approaches are not really suitable, as Patrick Whitefield says, for our “slug infested island”.
My orchard is a beautiful permaculture garden with espaliered apple trees and vegetables growing between them.
(left) Orchard in July 2009, vegetables on undug soil between apple trees, and (right) the same view in August 2011: trees are on M26 and MM106 and have scarcely diminished vegetable growth (yet!), except in dry summers.