I define weeds as plants you don’t want growing where they have appeared. It’s a personal call and does not mean they are evil plants, rather that they are strong growers and good at reproduction. Weed plants can spread over whole areas quite rapidly, either from seed or from roots.
This module is about having a clear strategy for clearing and staying clear of weeds. Neither underestimate weeds, nor fear them. Understand how they grow, so that you are well prepared for weeds that appear, and can stay ahead of their attempts to fill your growing space.
In the 1980s I visited the fields of other organic growers, and saw the work needed to prevent crops from being smothered by weeds. In 1987 I lost half an acre (2000 m2) of carrots to chickweed, after having prepared the soil with a rotavator.
These experiences helped me to understand how fine the line is between having a few weeds and having too many. I recommend you ignore those who advocate tolerance of weeds, because that approach can so easily lead to a big drop in harvests and, more importantly, to a lot of time wasted.
Some advocate ‘weeds as ground cover’, but when your vegetables and flowers grow strongly, they cover the ground. The soil is also covered by mulches of organic matter, such as compost, so with no dig I feel that ‘ground cover’ is not an issue. One way or another it’s always covered, but not with weeds.
Here are the underlying themes of Module Four:
- Be thorough with mulching in year one, especially on perennial weeds.
- Having zero or almost no weeds is an achievable state, and saves much time.
- Develop the habit of little and often weeding – much easier than being occasionally overwhelmed.
- Tolerate weeds in wild areas – many have flowers that attract insects – but keep a tidy strip around your growing area.
How no dig reduces the weed burden
In the 1980s, visitors were amazed when seeing my weed free market garden. I thought the lack of weeds was due to my mulching, and diligence. I was conscientious and hard-working, with a keen desire for clean soil. That came partly from a fear of being overwhelmed by weeds and losing crops, which I had seen happen too often.
However the same weed free effect has happened in all of my no dig gardens. I have come to understand how soil is actually calmer (for want of a better word) after being left undisturbed. It is calm rather than upset or disturbed, and therefore has no need to recover, or re-cover with weeds. Just like us: when disturbed, we need to recover.
- Soils which have been forked and pulverised, stirred, turned and lifted, are in a state of shock. They need to calm down and to recover – weeds are part of the healing process.
- Weed plants do a great job of growing fast, covering soil, and filling it with their healing roots when soil needs this help.
There are different weeds for different tasks, such as fast-growing, pioneer weeds for rapid colonisation of cultivated ground. Deep-rooting weeds, such as docks, are found on trampled and heavy soils.
Depending on the compost used, there may be a flush of weed seedlings on no dig beds in early spring, from seeds in the compost. Then, after you pull or hoe these, there is little growth of new weeds for the rest of the year.
By comparison, I notice that on the dig bed of my trial weeds keep germinating all year long. This is the more ‘usual’ situation faced by gardeners who dig and till. Plus the soil is sticky when wet, or hard when dry, and weeding is more difficult.
There are other considerations which I address in this module, such as weed seeds blowing in and weed roots zooming in from edges. The key approach is that, whatever their origin, you mulch weeds to clear them, with minimal disturbance. Your soil will love you for it!
Andy H, email, 20 October 2018:
‘I was close to giving up my allotment, partly due to the weeds!!! Your methods have given me the impetus I needed and I’m now working on the allotment!’
No dig gardeners love having so few weeds, and this is one of the many such comments I receive. The following one came from ‘Offwego’, when I had a website forum, 19 May 2018:
‘Shock horror, I actually found three weed seedings in my no dig onion bed today – the first of the year. Wind-blown from the adjoining overgrown plot.
Plot neighbours are asking if I am coming down very early in the morning as this year they never see me weeding; truth is I haven’t had any.
This system is far easier to maintain, and I find water retention is far better as well. With my old soil, as soon as I watered it disappeared; now the water is held in the compost.’
Perennial weeds
The most useful categorisation for understanding weeds is between perennial and annual types.
Perennial weed characteristics centre on the their persistence and durability:
- Roots survive removal of stems and leaves.
- Roots survive winter, often dormant with no leaves visible.
- Roots spread into new soil out of sight.
If left to grow, perennial weeds will also drop seeds when at a mature stage of growth. This means they have two ways to take over in a convincing fashion!
Woody perennial weeds
What I call a ‘woody weed’ has either stems of wood (brambles, any shrubs and young trees), or a fat and woody taproot (chiefly large docks). These are best dug out with a sharp spade, because otherwise their vigorous shoots grow through mulches.
You don’t need to remove all the roots, only the central clump of stems in the case of brambles, or the top 10–12 cm (4–5 in) of dock root. Once the digging out is finished, use your foot or the spade to firm soil down again.
Tree seedlings
Below is an elder tree (Sambucus nigra), starting life as a little seedling. If left for half a year, it would develop a woody tap root and already be difficult to pull. At Homeacres we also pull many hawthorn seedlings in spring (Crataegus monogyna); like the elder, their seeds arrive in the droppings of birds, who have eaten their berries.
We also pull seedlings of sycamore (Acer pseudoplatanus) and ash trees (Fraxinus excelsior). These are blown in by the wind – have a look around to see where you may be gaining weed seeds, be vigilant for them, and keep nearby edges as tidy as possible.
No dig success with mulching perennial weeds
It fascinates me how successful one can be at eliminating 100% of perennial weeds, simply by mulching the surface. When I say this on courses at Homeacres, there are sometimes diggers present who look surprised, even disbelieving, after their years of attempting to remove every last root of whatever perennial weed it was.
If soil is continually sifted in that search for every root, the disturbance is cumulative and massive. Therefore every tiny bit of broken root will make a huge effort to recover itself and the soil.
With mulching it’s the opposite, as roots gradually wither in situ from lack of food, due to no photosynthesis happening. Then suddenly they are completely gone, a happy moment for gardeners and a huge timesaver for years to come.
This was Evan on my forum, February 2018:
‘After 1.5 years not digging (mulching), what was once grass, oxalis, dead nettle, wild onion and the dreaded couch grass is now mostly weed free! I remove occasional weeds from compost or ones that blow in, but the recurring culprits have died!’
As well as the success we enjoy with mulching weeds, there is a feeling of the job being less intimidating and more achievable, fun even. This is Laura Evans after a day course at Homeacres, February 2020:
‘I spent several enjoyable hours renovating a neglected bed of raspberries using compost and polythene, a job so daunting I had put it off for months. Am feeling very empowered.’
Some perennial weeds, and how long they take to die under mulches
Bindweed
There are two types of bindweed, and they both take more than a year to eradicate, often two years:
- Hedge bindweed or bellbind (Calystegia sepium) is a vigorous climber with white, trumpet-like flowers and thick, fleshy roots, many of which lie close to the surface.
- Field (or lesser) bindweed (Convolvulus arvensis) has smaller leaves, thinner roots going deep, and mostly pink flowers that are small and discrete.
Girly HR Gardener on my YouTube Bindweed video, August 2018:
‘I had bindweed in my original allotment plot and by following no dig I have got rid of it, so now in my 3rd year there is no bindweed at all’.
Bramble (Rubus fruticosus)
To find the roots, cut and clear the thorny and trailing stems first. Brambles look more difficult to deal with than they actually are, because careful digging out of their relatively few root stems is enough to prevent regrowth, while the myriad of small roots can stay in the soil to decompose.
Use a sharp spade to cut around each cluster of stems, making a circle of cut soil, perhaps the size of a football. Then, with the spade end at 15 cm (6 in) depth, cut diagonally through the main roots, and lever out the whole surface bundle.
- Mulching without doing this is not effective, because the strong stems will push up and through.
Buttercup, creeping (Ranunculus repens)
Roots are wiry and tenacious, although quite shallow. Mulching sees them gone within 4–6 months of the growing season. They often grow from seed, and can be hoed when small.
Also in this family is celandine (Ranunculus ficaria), whose tuberous roots are tricky to extricate, but can be mulched from late autumn to early summer during their period of growth. They are spreading if left to grow, and have pretty yellow flowers in early spring.
Couch grass (Elymus repens)
In temperate climates, many gardeners have problems with couch grass, also called quack grass, crab grass and twitch. Its leaves are dark green and wider than many other grasses, and also a little hairy, while the white and spear-like root stems travel horizontally, and at some speed! This is a difficult weed to deal with if you are a digger. It grows in cool conditions as low as 6°C/43°F, survives freezing, and stays dormant in dry soil.
Mulching reveals its weak point: that most roots are near the surface and hold less store of food than other perennials, like bindweed. The whole root system often dies within a year, but you must be thorough. Always mulch a strip around the edge of your growing area, to prevent re-invasion.
Creeping thistle (Cirsium arvense)
It looks bad but is not difficult to eradicate. Wearing a glove, insert your fingers below the leaves and gently grasp the fleshy but firm stem. Then pull evenly and gently to remove 7–10 cm (3–4 in) of white stem, which grows up through mulches from deeper roots. Persistence pays, and this weed – although of daunting appearance – can be completely eradicated within a year, or even half a year, by mulching and then regular pulling.
Dandelion (Taraxacum officinale)
Along with many common salads such as lettuce and endive, dandelion is a member of the Asteraceae family. Its generic name derives from ‘taraxos’ meaning disorder, and ‘akos’ meaning remedy. The leaves are diuretic: cleansing for the liver and rich in minerals, and can be eaten in salads, even blanched. Roots dug out in autumn can be dried, roasted quite hot, and then ground to make a dark, earthy drink that is wrongly called a coffee substitute – I call it an acquired taste.
Dandelions colonise large areas by seed dispersal, from their ‘clock’ heads, mostly in late spring and early summer. They pull easily at the two or three leaf stage.
In the darkness under a mulch, large roots can survive for up to six months before expiring. They die more quickly in spring when growth is fastest, meaning root resources are used up more rapidly. In year one at Homeacres, just three months (from March to May) saw vigorous dandelions die under polythene.
Dock, broad leaved (Rumex obtusifolius) and curled (Rumex crispus)
Docks of both types have large leaves, with reddish stems from the broad leaves, and both are prolific seeders. Large docks are easier to clear than it may appear at first sight, using a sharp spade to slice through taproots, 15 cm (6 in) down. The remaining root will be weak and die under a mulch, as will small dock plants.
Other weeds of notable vigour from their taproots are Alexanders or horse parsley (Smyrnium olusatrum) and burdock (Arctium lappa). As with docks, use a sharp spade to remove the top part of taproots.
Ground elder or goutweed (Aegopodium podagraria)
A member of the carrot or umbellifer family, famously introduced by the Romans for its edible leaves – tasty as a filling in omelettes, raw or steamed. They are greens for the hungry gap, when other vegetables are scarce.
Eradicable in one year of mulching, some weak regrowth may need pulling in year two until it expires completely. The roots are tough, white, and of medium thickness, and tend to snap as they are being pulled. They travel horizontally more than vertically, and entwine around roots of other plants, making mulching around existing plants difficult. Cut thick cardboard to shape so that it butts up to the stems of plants, then keep pulling any new weed shoots near the stems for a year or more.
Horsetail, marestail or paddys pipe (Equisetum hymale)
An extremely vigorous weed, whose spiky stems and leaves appear as remnants of a prehistoric time. Horsetail prefers soil that is continually damp, and takes six years or more to die when all methods are used: mulching as well as pulling, and even hoeing. However its vigour diminishes over the years, and it is not invincible. I need to do a composting trial on roots of horsetail to check their survival rate. Until that happens, I suggest not adding the roots to your compost heap.
Stinging nettle (Urtica dioica)
These are a sign of rich soil, and are not difficult to remove because their roots are shallow and spreading – just wear gloves when handling large plants. Harvest the tips in spring for excellent soups and even eat as salad, chopped very fine to dissipate the sting.
Mulching works to kill nettles but may need a year. You can also slide a fork near the main roots, downwards at a 30 degree angle, to lever out the main clump of pale yellow roots. Smaller roots do not regrow. Seeding is prolific, and seedlings can be hoed.
Willowherb (Chamerion angustifolum)
An invasive weed, from seeds and roots. Seedling rosettes of shiny and dark green leaves can be mistaken for lambs lettuce and then, if left to grow, develop tenacious roots and also white, fleshy stems below soil level – these endure for many years, but can be pulled out.
Pretty pink flowers on a long stem in late summer turn to hundreds or thousands of feathery seeds. Germination occurs whenever soil is moist enough, including in mild winters.
John McConville, comment on You Tube Spring video, May 2019:
‘I have a field which has always been a weed and stone infested problem.With no dig and composting it’s turned into a small vegetable garden which is fantastic.’
Annual weeds
Annuals are easier to deal with – or are they? Their root systems are certainly less powerful than perennial weeds; however annual weeds can overwhelm from prolific seeding.
Two important qualities to be aware of are:
- Seed dispersal is their method of reproduction.
- They can flower and make viable seeds in a short time period.
Annual weeds do not regrow after being pulled, providing they are removed with some roots on the stem. All their fine roots can stay in the ground and do not regrow.
Alternatively, hoe them when so small as to be barely visible: you will be killing more weeds than you suspect, almost invisible ones with more root than leaf. After hoeing they can be left to dry and die in the disturbed mulch.
Annual weeds are in the group of pioneer plants, nature’s tool for creating life out of apparently not much. On bare rocks, lichens and moss, they are the first colonisers. On damaged soils, pioneer weeds grow exceptionally fast, faster than most cultivated plants. This explains the saying ‘chickweed follows the rototiller’. As do masses of perennial weeds, after the soil and their roots have been chopped up.
Pioneer weeds from seed, in temperate areas, include grasses, bittercress, groundsel, goosegrass, chickweed and charlock. Different climates and soils will see other weeds performing this valuable healing job.
With no dig there are many less pioneer weeds. At Homeacres we see them most often after compost containing weed seeds has been spread as a mulch. The main approach is to hoe, rake, scatter or pull seedlings of annual weeds, when they are barely visible. Mulches make this far easier (which I explain further in Lesson 12).
Examples of annual weeds – their size, and how to react to them when seen
The measurements refer to a mature plant’s height.
Bittercress (Cardamine hirstuta)
3–5 cm (1–2 in), with tiny white flowers that drop seeds just 4–6 weeks after appearing. Mostly a winter weed of cool and moist soil, with small leaves that are edible and tasty. Plants are small enough to go unnoticed, until they scatter hundreds of long-lived seeds at a young age. Remove when tiny and they pull out easily.
Charlock (Brassica arvensis)
6 cm (2 in), with pale yellow flowers which seed in 8–10 weeks. It germinates in all seasons, though mostly in spring, and can overwinter as a seedling. Often full of flea beetle holes but still able to set hundreds of seeds. Easy to hoe when small, and easy to pull when larger; don’t underestimate its ability to gain ground through speed and numerical advantage.
Chickweed (Stellaria media)
5–7 cm (2–3 in), a spreading habit with small white flowers within a month. It germinates in damp soil, often in early spring or autumn, and in mild winters too. The odd plant here and there is easy to remove, but its ability to set seed quickly can lead to a thick cover when it is often too damp for hoeing. Watch for it, and hoe seedlings or pull any small plants you see, with a firm tug of the almost wiry but shallow roots.
From Bob Paton CBE – Market Gardener at Hexhamshire Organics, October 2019
‘Moving to no dig is the best thing we have ever done. Weeds such as chickweed which were such a problem to us last year are no longer an issue.’
Fathen (Chenopodium album)
75 cm (30 in), with nondescript flowers turning to clusters of pale green seeds within six weeks, mostly in summer. A weed of rich soil, related to spinach and with edible leaves. Seedlings often appear in great number, and are tiny at first but subsequently grow large. Hoe tiny seedlings to avoid the pain of hand weeding high numbers of large fathen.
Grass, Annual Meadow Grass (Poa annua)
3–5 cm (1–2 in), with feathery seedheads just 6–8 weeks after germination. A small, tough and common plant, growing whenever soil is mild and moist for a couple of weeks, and with mostly superficial roots, which dislike drought at least. Common in mild winters and in any other damp season, difficult to hoe and best pulled when small. Older clumps have tough roots which hang onto a lot of soil when pulled.
Groundsel (Senecio vulgaris)
5–22 cm (2–9 in), sets seeds 4–8 weeks after germination. Easy to hoe or pull but beware, because even one plant setting hundreds of seeds can lead to much extra weeding in subsequent years. It germinates and grows fast at all times except midwinter, mostly in fertile soil; if soil is dry or poor, plants seed when very small.
Goosegrass (Galium aparine)
1.5 m (60 in) if supported, and with sticky leaves and stem. The seeds are also sticky, called cleavers, and they follow small white flowers. Common in the cool and damp of late winter, spring and autumn; fast-growing, and the stem tips are fantastic for our lymph systems. A big seeder if you allow it, and perhaps the stickiest weed of all.
Shepherds Purse (Capsella bursa-pastoris)
5–10 cm (2–4 in), with a cluster of pointed leaves and then a spiky flowering stem, seeds in 4–6 weeks. It is most easily recognised by its stem of seed pods or purses. The plants have a vigorous taproot which may be hard to pull, and they can be killed by cutting this main root with a hoe or trowel, preferably when still small.
Sow Thistle, Prickly (Sonchus Asper)
90 cm (35 in), but often smaller, pale yellow flowers, which set seed in as little as 4–5 weeks if soil is dry. It germinates in a wide variety of conditions and can overwinter, but is most common in late summer and autumn. Its leaves are less prickly than creeping thistle, and it’s related to perennial sow thistle (Sonchus Arvensis), whose fleshy roots are quick to colonise new ground. All sow thistles need hoeing or pulling as small seedlings, to prevent them from invading.
Speedwell (Veronica persica)
Mostly under 5 cm (2 in), with slender stems and pale blue flowers, seeds in 4–6 weeks.
Of the many kinds of speedwell, including the perennial ones, this is the most common. It grows mostly in winter and spring, has shallow roots, and is easy to pull when small. Be vigilant, as it seeds by the thousand, then being hard to control.
