The Gardener's LogControlling Weeds in Autumn: Which Ones to Tackle and How
Weeds do not stop growing in October. Many are setting seed or storing energy in their roots for the winter, which makes autumn a good time to deal with them. A couple of hours' work now can save a lot of work in spring, when everything wakes up at once.
Know which type you are dealing with
Annual weeds complete their life cycle in a year: chickweed, groundsel, hairy bittercress, shepherd's purse, annual meadow-grass. They spread by seed, often prolifically. The aim is to remove them before they set seed.
Perennial weeds come back every year from roots, rhizomes or crowns: dandelion, dock, creeping thistle, bindweed, ground elder, creeping buttercup, couch grass, nettles, bramble. These are the tough ones, because even a small piece of root can regrow.
Identifying them matters, because the best method depends on the weed. If you are unsure, take a photo and use a plant ID resource, or ask at a garden centre.
Autumn is the time to remove perennials
In autumn perennial weeds draw energy down into their roots to survive the winter. Digging them out now, while the soil is moist and workable, is easier than in dry summer ground, and the roots are fat and visible.
- Dandelions and docks: Dig out the whole taproot with a hand fork or a daisy grubber. Leaving a bit of root means they regrow.
- Bindweed and ground elder: These have white, brittle roots that spread widely. Dig carefully with a fork, shake out roots and remove every piece. You will probably need to repeat the process, as it is hard to get every fragment. Do not put the roots in your compost heap.
- Couch grass: Fork out the white roots (rhizomes) in a thorough sweep, as any left behind regrow.
- Brambles: Cut back and dig out the root crown. Cutting the stems alone encourages stronger regrowth.
- Nettles: Dig out the yellow roots, or cut back repeatedly. Nettles are also valuable wildlife plants, so it can be worth leaving a small patch in a corner.
- Creeping buttercup: Pull up the runners and roots, and improve drainage as it loves wet, compacted soil.
Hoe away annual weeds on dry days
A sharp Dutch hoe, used just below the surface on a dry, breezy day, slices off the seedlings, and the sun and wind dry them out. Do it regularly, and little and often is much quicker than doing it all at once. On a damp day, weeds can re-root, so pick them up. Always remove any weeds that have flowers or seed heads.
Mulching beats chemicals for beds
Once a bed is clear, cover it with a mulch to cut the amount of light weed seeds receive.
- Spread 5 to 7 cm of well-rotted compost, composted bark or leaf mould over damp soil. Keep it clear of plant stems.
- For heavily infested ground, lay cardboard (tape removed) overlapped by a few centimetres, wet it, and cover with a thick layer of mulch. It takes time to break down but suppresses most weeds and improves the soil underneath. This is sometimes called sheet mulching.
- Avoid plastic or non-permeable sheets under beds long-term, because they trap water and cut off air and the soil life that makes a good soil.
Making your own mulch from garden material is covered in clearing leaves and composting at home.
Paths, drives and patios
Weeds in paving joints can be scraped out with a knife or a purpose-made weeding tool, or brushed out with a stiff brush after rain. Boiling water works on small areas but can harm nearby plants. If you have pressure-washed a patio, refill the joints so the weeds find it harder to root, as described in our jet washing guide. Be careful with strong chemicals near drains, as the product can wash into surface water and harm water life.
Lawn weeds
Lawn weeds such as daisies, plantain and dandelions are best tackled by hand on a small lawn, while building a healthier lawn with good feeding and mowing makes it harder for them to establish. For selective lawn weedkillers, follow the label closely. They work best when the weeds are actively growing and the temperature is mild, so late autumn is often too late. More in autumn lawn care.
Weedkillers: when and how
Chemical weedkillers can be useful on tough perennials and for clearing a large area, but they have to be used responsibly:
- Always read the label and follow it to the letter, including weather conditions, protective equipment and the number of applications allowed.
- Do not spray in wind, rain, or near ponds, ditches, drains or watercourses.
- Keep pets and children away until the product has dried or as directed.
- Store and dispose of unused product as directed, and never pour it down a drain.
- Remember that professional use of certain products requires qualifications, and some products have been withdrawn or changed, so check what is currently approved for amateur use.
A weedkiller is a tool to use sparingly, not a first resort. Sometimes patient digging and mulching gets a better result.
Invasive and notifiable plants
Some weeds need special care.
- Japanese knotweed: It is not illegal to have it on your land, but it is an offence to allow it to spread into the wild. It can damage hard surfaces and affect property sales and mortgages. Do not cut it or spread it, and do not put it in your compost or green bin. Get a specialist to identify and treat it.
- Giant hogweed: The sap can cause severe burns when exposed to sunlight. Do not touch it, and seek expert advice for removal.
- Himalayan balsam and others: There are legal restrictions on spreading certain invasive non-native plants. Check government guidance.
What to put on the compost heap
Annual weeds without seed heads can go on the compost heap. Perennial roots, such as bindweed and ground elder, and weeds with ripe seeds, are best dried out thoroughly on a hard surface, then composted, or put in the council green waste bin if accepted, because a cool home heap may not kill them.
A simple autumn weed plan
- Dig out perennial weeds while the ground is workable.
- Hoe annuals on dry days.
- Mulch cleared beds with compost or leaf mould.
- Refill gaps in paving.
- Be careful and sparing with chemicals.
Clearing weeds from borders is a good time to deal with other tasks in the same area, such as planting spring bulbs.