Organic weed management
Weeds are often considered the organic grower’s biggest challenge as they compete with crops for nutrients, light and water. But not all weeds are bad. Some attract pollinators and others can improve the soil. And most can be composted, which will add nutrients to your soil.
Before you reach for the toxic weed killers, read on for information on:
- How to manage weeds on patios, paths and other hard surfaces.
- How to clear larger areas, such as an overgrown allotment or veg patch.
- Top tips on hoeing
- 100 individual weeds: how to identify, and how to manage.
- Five reasons why NOT to use toxic weed killer.
If you have an existing area of hard surface, you can rid it of weeds in one of the following ways:
- Carefully pour boiling water over them
- Remove them by hand with a sharp knife or trowel
- Use a flame or thermal weeder. These are particularly effective on young weeds.
You will need to repeat methods 1 and 3 every so often to keep on top of the weeds.
You can buy organic weedkiller from The Organic Gardening Catalogue which is based on pelargonic acid. This kills the foliage but doesn’t penetrate the root. Some use vinegar but this isn't something we would recommend as it's not been proved effective. Some councils use DEFRA approved acetic acid (the basis of vinegar) but as this acid is a synthetic chemical compound it is not certified for use in organic growing.
If you are creating a new path or patio, to minimise weed growth in future, make an impenetrable foundation layer: a geotextile membrane or a substantial mix of hardcore rubble and sand, firmly flattened to exclude all light and reduce moisture.
Cracks between pavers should be filled with mortar - not sand, which provides the ideal medium for weeds to germinate. Lime mortars are more environmentally friendly than cement mixes.
If you’ve taken on an allotment or veg patch covered in weeds it can be a daunting task to clear it. But don’t worry, here are our tips:
- Slash down high standing weeds and then cover the area with a thick compost manure mulch (at least 20cms) and tread down firmly. You can also use sheets of cardboard under the mulch. Without light the weeds will weaken and eventually die off. Use the slashed foliage and stems on the compost heap.
- Dig up deep-rooted weeds, such as dandelions and docks. Put foliage on the compost heap, and drown the roots in a bucket of water for a month or so. The water can be used as a liquid feed.
Persistent weeds such as bindweed and ground elder have to be dug over regularly, removing as much root as possible. Using the above mulching method will make the soil much easier to dig roots out after a few months. If bindweed or ground elder is woven into your herbaceous border, it is worth waiting until autumn then digging up individual plants which you want to keep.
Clean their roots of the weed’s root fragments, and then replace into a well-composted bed which has been dug over to get out the weed roots. Often it will take a few years of constant digging to weaken the weeds and make it easier to keep on top of them.
Put the weed foliage and roots (but not flowers or seed heads) into a black plastic sack. Tie up the top and leave in an out-of-the-way corner until it turns into gooey sludge, then compost it.
Remember, it is not just your own health that will benefit from not using toxic chemicals – you will be helping other life forms to thrive in your growing area. Leaving some weeds, such as a discreet area of stinging nettles, will provide food for pollinating insects, as well as leaves to make a liquid feed, high in nitrates.
3. Hoeing the the veg patch
Controlling weeds with a hoe is very effective. It allows you to easily kill weed seedlings, including those which have not yet appeared above the ground.
If your veg are planted in lines, with space between, then hoeing is easy. You can guide the hoe between rows, with a gentle push or pull, and not disrupt your chosen plants.
Hoeing is more difficult if your chosen plants are arranged randomly: it can be difficult to tell which is a weed seedling and which is a young veg plant, and sometimes it's not easy to manoevre the hoe between clumps of plants.
When to hoe
- The best time to hoe is before you have a problem with the weeds, even before they appear on the surface. Weed seedlings are developing all the time just below the soil surface and if you hoe regularly these weed seedlings will be disturbed and killed.
- It's good to hoe when the soil surface is dry. This means when the weeds are chopped off they won't reroot in moist conditions.
- Hoeing early in the morning allows the weed growth to lie on the surface and dry out as the day passes.
How to hoe
- First, make sure that when you hoe you are as upright as possible. This makes it easy on your back. The length of the hoe is key to this.
- Also keep your hoe blade sharp. This allows you to cut the weed from the roots at just below soil level.
- Push or pull the hoe through the soil, approx one or two centimetres deep.
- You can leave the uprooted weeds on the soil to dry in the sun.
4. Individual weed information
Knowing about a weed’s habit, biology, persistence & spread will help you to keep on top of it. Here is detailed information on more than 100 individual weeds, from dandelion to creeping buttercup, bindweed and ground elder.
- Weeds can contribute to your growing area's biodiversity. To use toxic chemicals to obliterate them is simply not necessary.
- Most contain glyphosate, which has been found to be carcinogenic.
- Glyphosate is usually mixed in chemical formulations to make it more effective. These formulations, such as Roundup or Weedol Path Clear, are potentially far more dangerous.
- None of these formulations has been independently tested for safety. Government regulatory bodies only test individual components, and industry never reveals their exact make-up.
- Independent research has revealed that glyphosate also affects the body’s endocrine system – causing problems in the liver and kidneys. Industry testers dispute this, but have declined to reveal all the results of their safety tests.
Garden Organic has over 60 years of research into organic weed management. Working with farmers, we conducted huge field-scale investigations. Here are some of the results.
Crop rotation produces healthy soil, healthy plants and good yields. It can also help manage weed infestation.
Direct control methods
Although organic crop rotations can mitigate weed infestation, it is likely that some form of direct action - mechanical or manual - will be needed against weeds to prevent crop loss.
Crop weeding strategies for farmers
A list of how to control weeds the organic way within specific crops, from alliums to rhubarb.