Updated: Oct 28, 2020
No-dig garden beds (raised or in-ground) and containers are fundamental to urban permaculture. Whether you live in a suburban neighborhood and tend a backyard garden, or nurture soil-filled growbags on a sunny window ledge or rooftop in Brooklyn, your efforts will be more productive, beautiful and righteous if you adopt a no-dig philosophy. I promise.
Why? Because at its roots, no-dig mimics nature's logic, and in following her you simply cannot go wrong (or at least, not often). In natural ecosystems undisturbed by human intervention, nature top-dresses the soil from above and from the forest canopy, while simultaneously and invisibly conducting a symphony of beneficial relationships below ground. Happy 'contained' soil looks very much like moist chocolate cake to me, offering a deep brown-black damp, sticky sponginess much like a black forest chocolate cupcake.
This is no accident. Healthy soil is busy soil, supporting an ecosystem of visible and microscopic organisms whose job it is to decompose plant residue and carry out a range of important functions. The less disturbed (tilled, dug) the soil and the greater the amount of beneficial organic matter retained, the more plant residue and food there is to support biological activity.
Worms feed on decomposing plant matter, and as they move through and poop in the soil they aerate and fertilize at the same time - contributing to the sponge and structure. In circulating, feeding and pooping, worms and larger insects are captive, living recyclers of soil.
Tiny microfauna like protozoa and nematodes, and microflora like fungi and bacteria are equally important to soil biology and play specific roles within the biomass of the soil.
I am blown away by what goes on below ground, and while I certainly don't understand soil biology in its entirety, I know a few things about dirt. Whenever possible, use an organic soil or organic green compost as a planting medium, over manufactured sterile soil mix. Further, support that soil by emulating nature in managing what goes into it and how it comes out.
I do not dig, turn over, or otherwise unnecessarily disturb the soil, and never use synthetic fertilizers or insecticides that would harm organisms and kill or harm soil biology. We harvest plants at soil level by cutting the stems and leaving the root structure to decompose naturally and become food for organisms. There are exceptions of course, but very few.
Disturbing the soil can damage or destroy the airy network of tunnels that worms and insects worked so hard to create, and it breaks the mycorrhizal network of fungal hyphae (mushrooms are the fruiting bodies of this underground network) that can traverse thousands of miles back and forth through the soil contained in a single small bed. This network creates mutually beneficial relationships with plant roots and root hairs, exchanging nutrients and minerals, and increasing the nutrient and moisture absorbing surface area and capabilities of the roots.
When nature composts from the top with leaf litter and decaying matter, organisms in the soil come to the surface to feed and pull the matter down below the soil - aerating and adding structure in the process - and the decomposition process is enhanced.
I have smallish planter pots and feed-trough planters that have supported very healthy tomato plants, fruit trees, and root vegetables for well over a decade. I have never replaced the soil or turned it over by digging. I do top-dress every year with organic compost, as the soil levels naturally drop as organisms and plants feed on the soil, breaking it down and turning it into food for my family.
Organic compost soil is available from most plant nurseries and garden centres in bags, and quite often you can find a double or triple-screened version for using as a seed starter mix. I simply screen organic compost myself through an old plastic strainer and by rubbing the compost between my palms. It works beautifully, in part because it holds moisture better than prepared mixes, and extra lightness afforded by sifting creates a lighter weight, extra-aerated medium that gives tender seedlings an easier go of breaking through the maleable soil.
Large quantities of organic green compost is becoming easier to find, as organic farmers are creating cash-crops from their trimmings and surplus. So-called veggie mix is often very similar to organic compost, but be sure to double-check before purchase. As I am still expanding my permaculture garden and adding beds in ground and above ground, I typically order a small tip-truck load of organic topsoil in the spring, using the bulk of it and saving a quantity to age, for use later in the season.
An autumn top-dress of compost at the end of the season, seems to give my dormant winter garden and container plants a bit of an edge in transitioning to damp and cold. My intuition tells me that this may be particularly important in colder climates and in small space gardens where compost doubles as mulch. Many no-dig gardeners disagree with a fall feed, but I think we should all do what works best in our gardens and for our schedule. This works for me.
And the very best part - that things that converts diggers to no-diggers - I've left for last. No-dig equates with far, far fewer weeds. There are virtually no weeds in my no-dig gardens that utilize fully-cooked green compost as a growing medium. Proper composting effectively kills weeds seeds and if left undisturbed, buried weed seeds rarely germinate. Even no-dig beds comprised of garden variety dirt, if left undisturbed should become relatively weed-free once they develop healthy soil biology, structural integrity, and germinated weeds have been spent. Of course you will see the odd sprout here and there from a seed deposited one way or another by a bird or a small furry creature, or by the wind, but those are beautiful signs of a healthy, living, organic garden that welcomes and supports wildlife.
raised beds such as those pictured above should be bottomless, encouraging the exchange of nutrients, minerals and moisture between the soil in the beds and the soil beneath the beds, unless of course the site is or was contaminated.
a bases layer of upturned composted sod, or double thickness of brown box cardboard (edges overlapped) underneath the growing medium will a) kill any existing grass, and b) prevent errant grass and weeds from growing up into the beds.
When creating raised no dig beds without sides, it is advisable to lay cardboard, recycled black plastic or other opaque material over the bed area several months in advance (winter is ideal for this), to ensure that the grass dies off completely first.
containers gardens especially, should never dry out completely, as this can kill organisms and collapse the moisture-absorbing capacity of roots networks.
cut vegetation at the soil level whenever possible, leaving root structures in place to recompose and feed organisms in the soil.
do not dig or till soil; in nature, disturbed soil self-mulches with cover in the forms of weeds and grasses. When starting with well-composted soil there will be few weeds from the outset, but regardless, a no-dig ethos will generate similar results over time.
ensure that container beds have adequate drainage, to avoid water pooling.
top-dress annually with organic compost (or soil) or the closest available thing to it.
denser plantings tend to act as natural mulch, keeping the soil cooler and moister.
treat container beds and pots as you would raised beds, but on a smaller scale.
water the soil as opposed to the plants; this helps prevent rot, slugs and pests.
the undisputed king of no-dig gardening, in my book anyway is Charles Dowding, whose Somerset, UK market garden 'Homeacres' runs regular comparative trials.
To watch the Modern Farmer | Million Gardens Movement video "No Dig Beds" featuring our urban permaculture garden, on YouTube click here.
Subscribe to the Modern Farmer channel watch future permaculture segments.
To read more about soil and fungi, and their relationship to bees, visit Beemushroomed, a Love Affair with Bees.
Happy no-dig gardening.