Spring is here, which means trees and shrubs aren’t the only things blooming. So is the itch in the mind of every gardener to start working on this year’s flowers.
We do not want to prune your enthusiasm, but you may want to sheath the shovel and stow the hoe, as the prevailing wisdom on the science of the soil is to go easy on the soil in your garden.
No-dig gardening is quickly becoming the way to grow for soil scientists and horticulturists. The reasoning is simple: it’s a greener and easier way to grow plants and vegetables.
But why digging is not good?
“Digging disrupts the natural processes that keep the soil healthy and productive,” he says Guy Barter, chief horticulturist at the Royal Horticultural Society (RHS). “Minimizing cultivation is desirable when trying to grow plants in ways that have the least environmental impact.”
Excavate the earth bulldozes a number of underground structures. The drainage channels created by the worms are destroyed, the important fungal networks are broken and the carbon that has been locked in the soil is released into the atmosphere.
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Digging also brings weed seeds closer to the surface, making them sprout more easily.
Barter and his team use no-dig gardening methods in the RHS gardens. He says that the benefits do not require the best crops, although other gardeners have reported higher yields.
Charles Dowding, a champion of no-dig gardening, compared beds side-by-side over eight years. One was dug, the other was not. He reported 100 kg of additional products from the bed without digging.
So how do you grow a garden without digging? Instead of tilling the soil, no-dig gardeners cover their beds with a layer of mulch or well-rotted organic matter, either from their compost piles or from the garden center.
If the soil is weedy, just cover it with a few sheets of cardboard, says Barter. Then add another layer of compost on top (this is sometimes known as lasagna gardening).
“The trees will be cleared,” says Barter, “and the plants will root in the soil below, which will be enriched by the activity of the worms that carry the compost into the soil below.
“There is no need to use expensive wood to make beds and they do not need to be very high – 15 cm (6in) is enough to get the benefits of raised beds. Try not to step on your beds, because this will compact the soil, especially in wet weather, and the compacted soil may need to be dug up.”
If that all sounds a bit… well, easy, there’s another trendy technique to try. Hügelkultur is used to make brownfield sites more fertile. It involves creating a mountain from decaying wood and other compostable matter and then turning it into a raised bed.
“The theory is that decaying wood supports a wide range of fungi and other organisms that could be beneficial to soil and plant health, and promote good crops,” says Barter.
“Like other raised bed techniques, it is especially useful where the underlying soil is poor.”
Barter recommends trying a small patch first, maybe 2m2 (22 feet2). Create a shallow trench and fill it with fallen logs, twigs and branches. Add mulch, compost or other organic matter on top and finish with soil.
It’s a cheap approach to gardening and, like the no-dig method, it simulates what happens in nature. To date, there has been no robust research in hügelkultur, but rotting wood is thought to promote nutrient-rich soil and also act as a sponge, retaining moisture to keep plants watered.
In addition, because the wood takes so long to decompose, the bed should be pushing daisies (literally) for years to come.
Late winter is the perfect time to experiment with the no-dig garden. The soil should be less waterlogged and you can prepare your garden just in time for the spring season.
It’s not a zero-work approach to gardening, but it’s definitely lazier and more sustainable. Sometimes, it’s really easy to be green.
About our expert:
Guy Barter is the principal horticultural adviser at the Royal Horticultural Society (RHS). He joined as trials superintendent at RHS Garden Wisley in 1990, following experience in the world of commercial horticulture after graduating with a degree in horticulture. After this, he went on to run the RHS Member Advisory Service. A self-described gardener who likes to get his boots muddy, Barter grows fruit and vegetables in my spare time and experiments to try and test new plants, methods and products.
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