Do I have to declare Japanese knotweed? The law explained

Selling a house with knotweed

The Law Society's TA6 Property Information Form is the questionnaire sellers fill in for the buyer's solicitor in England and Wales. The 6th edition, in use since 30 March 2026, asks about Japanese knotweed at questions 8.6 and 8.7: whether it is present, and whether there has been a survey and a management plan. Its notes say a property is usually treated as at risk if knotweed is growing on it or within three metres of its boundary.

The form asks for answers that are truthful, complete and as accurate as possible, and warns that a buyer who is given misleading information may be able to claim compensation after completion. Answering no means being confident there is no knotweed or rhizome within that three metre zone. Not known is an accurate answer where nobody has looked, though the buyer will often then ask for a survey. Where there is knotweed, attaching the specialist survey, the management plan and any guarantee helps keep a sale moving.

Scotland's conveyancing works differently, through the Home Report, but the surveyor's knotweed assessment follows the same professional standard described below.

Having it is legal; spreading it is not

Government guidance for England says there is no legal duty to remove Japanese knotweed from your own land unless it is causing a nuisance, but that you must stop it spreading off your property.

Section 14(2) of the Wildlife and Countryside Act 1981 makes it an offence in England and Wales to plant, or otherwise cause to grow in the wild, any plant listed in Schedule 9, and Japanese knotweed is on that list. On conviction in the Crown Court the penalty is up to two years in prison, a fine, or both. Scotland's version of the offence is wider and its maximum sentence longer.

Dumping cut stems or contaminated soil over a fence, in woodland or on a verge is a common example of the offence.

Neighbours, nuisance and community protection notices

Knotweed that crosses a boundary can be the basis of a civil claim. In Network Rail v Williams and Waistell [2018] EWCA Civ 1514, the Court of Appeal held that encroaching knotweed rhizome is an actionable nuisance because it burdens the neighbour's land and reduces its value, before any physical damage appears.

Councils and the police in England and Wales can also use community protection notices under section 43 of the Anti-social Behaviour, Crime and Policing Act 2014, where conduct has a persistent, unreasonable and detrimental effect on the quality of life of people nearby. A written warning comes first. Failing to comply with the notice is an offence carrying a fine of up to £2,500 for an individual and an unlimited fine for a business. The fixed penalty that can be offered instead is up to £100; from 26 October 2026 councils can set it at up to £500.

Mortgages and the three metre rule

Surveyors valuing homes for lenders work to the Royal Institution of Chartered Surveyors (RICS) professional standard on Japanese knotweed, in force since March 2022. It replaced the old seven metre distance with three metres, and sorts sightings into four categories.

For categories A and B, RICS expects most lenders to want an inspection by a specialist belonging to a trade body and a management plan backed by an insurance backed guarantee, possibly with a retention. RICS also says it is not appropriate for a lender to demand treatment of knotweed on a neighbour's land.

Disposal rules

Cut knotweed and soil containing rhizome may be classed as controlled waste. It must not go in a garden waste bin or to a household recycling centre, and anyone carrying it away for a business must be a registered waste carrier taking it to a landfill or incinerator with the right permit. The government guidance for England adds that whoever sends it off site must tell the Environment Agency where it went.

On site burial is allowed at a depth of at least 5 metres, or 2 metres inside a sealed geotextile membrane, with the Environment Agency told at least a month beforehand. Businesses that burn it must notify the Environment Agency a week in advance, inform the council's environmental health team and register a waste exemption. Anyone spraying it needs a certificate of competence in herbicide use or direct supervision by someone who holds one, and spraying near water needs the agency's agreement.

Getting it treated

A specialist survey costs £250 to £800. A herbicide programme on a stand under 50 square metres runs £1,500 to £3,000 over three to five years, and full excavation with off site disposal on a domestic plot runs £4,000 to £20,000. The questions to ask are membership of the Property Care Association or the Invasive Non-Native Specialists Association (INNSA), the length and underwriter of any guarantee, and the sprayers' certificates, because the paperwork from the treatment is what a buyer's solicitor and lender will want to see.