In short
In England, GOV.UK says you do not legally have to remove Japanese knotweed from your land unless it is causing a nuisance, but you must stop it spreading off your property, and you can be prosecuted for causing it to spread into the wild. Treatment with approved herbicides “usually takes at least 3 years”, and a new plant can grow from a piece of root (rhizome) as small as 1 cm. Soil containing knotweed may be classed as controlled waste. A buyer should ask the seller about it, ask the surveyor to look, and ask the lender what it requires.
What the law says
Spreading it is the offence, not having it. Section 14(2) of the Wildlife and Countryside Act 1981 makes it an offence to plant “or otherwise cause to grow in the wild” any plant listed in Part II of Schedule 9. It is a defence to prove that you took all reasonable steps and exercised all due diligence to avoid the offence (section 14(3)). The section is marked as applying to England and Wales.
Nuisance. GOV.UK’s wording sets the line: no legal duty to remove knotweed “unless it’s causing a nuisance”. A neighbour’s complaint about knotweed crossing a boundary is therefore a matter to raise with a conveyancer before buying.
Who deals with it. GOV.UK makes clear that the Environment Agency is not responsible for dealing with knotweed: it is the landowner’s responsibility.
How it spreads and how it is treated
GOV.UK names four invasive knotweeds in the UK: Japanese (the most common), dwarf, giant and Bohemian (hybrid). They spread by root growth and by fragments of stem and rhizome. Rhizome can lie dormant in the soil for many years and regrow if disturbed or moved.
| Method | What GOV.UK requires or advises |
|---|---|
| Spraying or injecting | Approved herbicides only; respraying needed; at least 3 years. Sprayers may need a certificate of competence. Near water, Environment Agency agreement is needed. |
| Burying on site | Notify the Environment Agency at least one month before. At least 5 metres deep, or 2 metres with an undamaged geotextile membrane. |
| Disposal off site | Through a registered waste carrier to a permitted facility. |
GOV.UK advises against treating it yourself unless you have the skills and experience, and points to specialist companies.
What a buyer should check
- Ask the seller in writing whether knotweed is or has been on the property, and whether a treatment plan exists. Your conveyancer gathers these answers with the other pre-contract information: see conveyancing explained.
- If treatment is under way, ask for the plan, the contractor’s details and whether any guarantee transfers to you.
- Ask your surveyor to look for it; a survey is a visual inspection: see home survey levels.
- Ask your lender what it requires. Each lender sets its own policy; there is no official rule for mortgages on affected homes.
- Check the boundary: knotweed on a neighbour’s land close to yours raises the nuisance question above.
Scotland, Wales and Northern Ireland
The GOV.UK guidance applies to England and links to separate guidance for Scotland, Wales and Northern Ireland. In Wales, see Natural Resources Wales; in Northern Ireland, nidirect’s page on invasive non-native plants. Payotte has not summarised the rules of the other nations here: check with the nation’s environment body before relying on the English position.
What it costs
There is no official cost of treatment: it is set by the contractor and depends on the size of the stand and the method. Budget for at least 3 years of treatment if you spray, according to GOV.UK.
Which professional to consult
A surveyor can identify a suspected stand. A conveyancer reviews the seller’s answers and any treatment guarantee. A mortgage adviser can find lenders’ positions. See also property searches, flood risk when buying and, where a stand sits near the line with a neighbour, property boundaries.
Frequently asked questions
Is it illegal to have Japanese knotweed in your garden?
No. GOV.UK says you do not have to remove it unless it is causing a nuisance, but you must stop it spreading off your property.
Can you be prosecuted over Japanese knotweed?
Yes, for causing it to spread into the wild. Section 14(2) of the Wildlife and Countryside Act 1981 makes that an offence, with a due-diligence defence.
How long does knotweed treatment take?
GOV.UK says spraying usually takes at least 3 years, and dormant rhizome can regrow if disturbed.
Can I put knotweed in my garden waste bin?
GOV.UK says contaminated soil or plant material may be controlled waste, to be disposed of through a registered waste carrier to a permitted facility.
Who is responsible for knotweed, the council or the owner?
The landowner. GOV.UK says the Environment Agency is not responsible for dealing with it.
General information drawn from the official sources cited and dated on this page. It is not legal, tax or financial advice: for your own situation, ask a licensed professional.
More guides on buying
- Buying a home in England: the steps, offer to registration
- Buying a home in Northern Ireland: process and registers
- Buying a home in Scotland: Home Report, offers and missives
- Buying a listed building: consent, offences and checks
- Buying a new-build home: reservation, snagging and warranties
- Buying a second home: SDLT, ADS and LTT higher rates
- Coal mining searches when buying a home in the UK: reports, costs and subsidence claims
- Conveyancing explained: who does it and what it covers
- Exchange and completion: when you are bound to buy
- First registration of unregistered land in England and Wales
- First-time buyer relief: England, Scotland and Wales
- Flood risk when buying a home: maps, zones and Flood Re
- Gazumping and gazundering in the UK: why they are legal before exchange and how to protect yourself
- Home survey levels 1, 2 and 3: which one to choose
- Joint tenants or tenants in common: buying a home together
- Land Registry fees in the UK: Scale 1, Scale 2, Registers of Scotland and LPS compared
- Land Transaction Tax in Wales: rates, higher rates, 30 days
- LBTT in Scotland: rates, first-time buyers, ADS, 30 days
- Lease extension cost: how the premium is worked out (England and Wales)
- Leasehold and freehold: what you own, and 2024 reforms
- Missing planning permission or building regulations sign-off: what it means when buying
- Non-UK resident SDLT surcharge: the 2% and how to reclaim it
- Property searches when buying a home in the UK
- Restrictive covenants, easements and rights of way on a UK property
- Right to Buy: discounts, rules and where it still exists
- Stamp Duty Land Tax: rates, who pays and the 14 days
- Stamp duty refund on higher rates: reclaiming the surcharge after selling your old home
- The Home Report in Scotland: contents and your rights
- The title register: what it shows and how to get it
Sources
- How to stop Japanese knotweed from spreading (GOV.UK, Environment Agency, Defra and Natural England, updated 12 February 2026) (consulted 21 October 2026)
- Wildlife and Countryside Act 1981, section 14 (legislation.gov.uk) (consulted 21 October 2026)
- Invasive non-native plants (nidirect) (consulted 21 October 2026)