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First allotment

How to clear an overgrown allotment

The short answer

Clear it in sections: cut down the top growth, dig out brambles and the roots of perennial weeds where you will grow this year, and cover the rest with a light-excluding mulch. Winter is the best time to start. Covering needs at least one growing season, and deep-rooted weeds like couch grass, bindweed and horsetail can take years; RHS says don't worry if it takes several seasons.

There is no fast way to clear perennial weeds, and the sources disagree on the slow ways. What they agree on is doing it a piece at a time, so that part of the plot is growing while the rest is being cleared.

Step by step

  1. Start in winter, before the growing season.(RHS)
  2. Divide the plot into sections and tackle one at a time.(National Allotment Society)
  3. Check long grass for hedgehogs and slow worms before strimming.(BBC Gardeners' World Magazine)
  4. Cut brambles and woody growth down and dig them out; shred woody waste for compost.(RHS)
  5. Remove perennial weed roots such as bindweed, couch grass, ground elder and nettles, and don’t compost them.(RHS)
  6. Cover what you can’t clear yet with an opaque mulch. RHS says it needs at least one growing season.(RHS)

The weeds that come back

  • Rotavators can spread perennial weed fragments if used carelessly.(National Allotment Society)
  • Docks and dandelions: Garden Organic drowns the roots in a bucket of water for a month before composting.(Garden Organic)
Perennial weeds and what RHS says about them
WeedWhat RHS says
Couch grassCover with cardboard and about 20cm of organic matter, and leave it for at least a few years.
BindweedRegenerates from tiny root fragments. Keep the soil covered for a few years.
DocksRemove the top 12 to 15cm of root; deeper sections are unlikely to regrow. Seed can arrive in manure.
Horsetail (mare’s tail)Rhizomes up to 2m deep. Avoid digging or rotavating, which spreads fragments; eradication can take many years.
Japanese knotweedReport it, and have it managed through your council or a licensed specialist.
RHS weed pages, and the National Allotment Society for knotweed.

Where the sources disagree

Where the sources differ
QuestionRHSOthers
How long to coverAt least one growing season on the allotment page; a few years for couch grass and bindweed.National Allotment Society: black plastic usually 12 to 24 months. Gardeners’ World: at least two years for couch.
Dig perennial weeds out?Weed pages: avoid digging or rotavating couch, bindweed and horsetail, which regrow from fragments.National Allotment Society: couch grass needs persistent digging, removing every piece.
Plastic sheetingOpaque mulch, not carpet.Mole Valley: membrane only as a short-term solution. Wirral: avoid plastic-based membranes.
WeedkillerDoes not support weedkillers; all weeds except Japanese knotweed can be controlled without them.Wirral: use sparingly and follow the label, avoiding drift onto other plots.

While the covers are down

  • Grow on what you have cleared. Potatoes, courgettes and squash smother weeds.(RHS)
  • Or sow a green manure to protect and improve the soil while keeping weeds down.(National Allotment Society)
  • Garden Organic’s mulch: slash the weeds, cover with cardboard and a thick compost or manure mulch, ideally at least 20cm, trodden down.(Garden Organic)

Put your plot on the plan, free

Add your beds with their sizes, roughly is fine, and Vercro draws them to scale, keeps a record of what grew where, and shows what each empty bed could take next.

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Where this comes from

The growing advice on this page comes from the published sources below, each linked beside the point it supports. Where two good sources disagree, we show both rather than choosing the convenient one. Reviewed 19 September 2026.