RHS horticulturist Liz Mooney uncovers the myths and surprising benefits surrounding this increasingly popular way of growing
In my mind, ‘no digging in the garden’ has the same appealing ring to it as ‘no washing up after dinner’. But is it really that simple?
What’s the deal with no-dig gardening? In a nutshell, no-dig gardening involves little or no soil cultivation. Instead, the ground is covered with a thick layer of well-rotted organic matter every year. This is left for soil-dwelling organisms to incorporate into the ground (effectively, they do the digging).
Until relatively recently, I dutifully dug my allotment with pride, but since I started working at RHS Wisley’s World Food Garden, where we’ve practiced no-dig from the outset, I’m now a convert and an advocate of this method.
Why the change in thinking? Studies, particularly those conducted by Charles Dowding at his garden, Homeacres, consistently show that higher yields can be achieved by avoiding soil cultivation where possible. Between 2013 and 2020, in side-by-side comparison beds (where the same crops were grown and equal amounts of organic matter were added, but one was dug and the other wasn’t), he produced 855kg of no-dig produce, compared to 755kg with digging.
This leaves me wondering if digging was dreamt up as work creation for Victorian garden apprentices, to keep them warm and busy through winter. In the photo below, two students of old diligently double-dig the trials field at RHS Garden Wisley – this was the standard way of preparing soil for generations.
However, we greatly benefit from the investigative work of modern day soil science. This has shown that low or no cultivation (i.e. minimal digging) creates a more balanced soil ecosystem. Fauna overwintering in the soil is protected, so there is a larger population of beneficial organisms ready to help control those you may not want.
Soil is also healthier, with many more mycorrhizal associations (beneficial fungi that attach to roots), and the reach of the root system is greater, allowing plants to gather water and nutrients from further afield. This leads to soil that supports healthier, stronger plants, and means additives and fertilisers aren’t needed. I apply no fertilisers of any kind to my beds and still get impressive harvests.
Want fewer weeds on your plot? Digging soil over brings weed seeds to the surface, where they soon germinate, sometimes in surprising numbers. No-dig prevents this, although woody weeds such as brambles may need removing before starting your plot. Otherwise, weeding is minimal. An initial layer of cardboard laid over the ground at the outset will suppress most unwanted weeds and grasses, meaning there are usually much fewer weeds on a no-dig plot.
Doesn’t soil get compacted if it’s not dug? People often confuse firm and compacted soils. True compaction only significantly occurs after prolonged heavy machinery use (not through footfall). However, most plants actually root better in firm soil than loose. At Homeacres, in a trial where the surface of the soil was loosened every year, the loosened ground produced around 5% fewer crops than a comparison in which the soil was left undisturbed.
I’ve also found that I water less, since soil structure is left intact. No-dig improves drainage, allowing water to sink in slowly. It’s then held at the roots, where the plants need it most, rather than draining away.
Environmentally speaking, carbon is locked into the soil in a no-dig scenario. Dug soil that is exposed to the elements releases CO2. So the no-dig carbon reservoir helps in the battle against climate change.
I believe that no-dig is better for the soil and therefore better for plants, and I would encourage everyone to give it a try. Here are my tips for getting started.
How to start a no-dig plot
First, remove perennial weeds like brambles, thistles, docks and nettles. Collect plenty of thick cardboard, re-purposed from packaging. Lay this over the ground, with plenty of overlap to prevent anything pushing up in the gaps. There’s no need to remove existing turf, as no-dig pioneer Charles Dowding (above) demonstrates as he lays down a double layer of cardboard to extend an existing veg bed in his own garden, Homeacres.
Cover the cardboard with a thick layer of organic matter (10-15cm deep), using well-rotted homemade compost. You can then sow or plant veg plug plants directly into the mulch.
And don’t forget – the powerhouse of the no-dig method is a good compost heap!
Pick of the crop
Look for the RHS Award of Garden Merit (AGM) when buying vegetable seed or small plants. You can also download the RHS lists of recommended cultivars.
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About the author – Liz Mooney
I am a horticulturist with the edibles team at RHS Garden Wisley, working mainly in the World Food Garden. I also give regular talks about fruit and veg growing at our Hilltop Live events. In my spare time, you’ll find me working on my own allotment.