Japanese knotweed and the law

It is not illegal to have Japanese knotweed on your land, and you have no general legal duty to remove it or to report it. The law steps in when knotweed spreads or is handled carelessly: causing it to grow in the wild is an offence, waste rules govern how it is moved, and in England and Wales councils can serve notices and neighbours can sue when it reaches their land. The rules differ between England, Wales, Scotland and Northern Ireland.

Having knotweed on your land

The House of Commons Science and Technology Committee confirmed this position in its 2019 report on knotweed. In England, government guidance goes further: you must stop knotweed on your land from spreading off your property, although you are not legally required to remove it "unless it's causing a nuisance". The Environment Agency can give guidance, but dealing with knotweed is the landowner's responsibility. Wales, Scotland and Northern Ireland have their own guidance.

What you must tell a buyer when you sell a house with knotweed is a separate question.

The planting offence

In England and Wales, 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. Japanese, giant and hybrid knotweed are all listed. The current England and Wales entries were added on 6 April 2010, replacing an older entry under the name Polygonum cuspidatum, and GOV.UK guidance confirms that causing knotweed to spread into the wild can lead to prosecution.

It is a defence to show that you took all reasonable steps and exercised all due diligence to avoid committing the offence. The maximum penalties are set by section 21 of the Act. On summary conviction in the magistrates' court, the maximum is an unlimited fine, up to six months in prison, or both; on conviction on indictment, it is a fine, up to two years in prison, or both.

A "£5,000 fine" is still sometimes quoted, including in the 2019 Commons report, but section 85 of the Legal Aid, Sentencing and Punishment of Offenders Act 2012 removed the £5,000 cap on magistrates' court fines for offences committed on or after 12 March 2015.

Species control orders

Since 12 April 2015, environmental authorities in England and Wales have been able to use species control agreements and orders under Schedule 9A of the 1981 Act, inserted by the Infrastructure Act 2015. In England those authorities are the Secretary of State, the Environment Agency, Natural England and the Forestry Commissioners; in Wales, the Welsh Ministers and Natural Resources Wales.

An order can require an owner to carry out work to eradicate or control an invasive non-native plant, or to let the authority do the work, and failing to comply without reasonable excuse is an offence. We have found no published evidence of how often, if ever, these powers have been used for knotweed in a domestic garden.

Community protection notices

Community protection notices (CPNs) were created by the Anti-social Behaviour, Crime and Policing Act 2014 and apply in England and Wales. Home Office guidance says a CPN can require someone to control or prevent the growth of Japanese knotweed.

The test is whether a person's conduct is unreasonable and has a persistent or continuing detrimental effect on the quality of life of those in the locality. Section 57 of the Act provides that "conduct" includes "a failure to act", so doing nothing about knotweed can be enough if the rest of the test is met.

Councils and the police can both issue a CPN, although it will usually be the council, and a written warning must come first. A notice can be served on an individual aged 16 or over, or on a business or organisation, and can require the recipient to stop specified behaviour, put matters right within a set time and take reasonable steps to prevent a recurrence.

Failing to comply with a CPN is a criminal offence under section 48:

The fixed penalty is set by section 52, and the rise to £500 is made by section 4 of the Crime and Policing Act 2026, which comes into force on 26 October 2026. The £20,000 figure for organisations in the original Home Office note is out of date.

It is a defence to have taken all reasonable steps to comply, or to have some other reasonable excuse. The Home Office note adds that the community trigger, a formal review of an anti-social behaviour case, could apply to persistent knotweed problems.

Waste and disposal

GOV.UK guidance says soil or plant material contaminated with Japanese knotweed may be classified as controlled waste, which brings in the duty of care under section 34 of the Environmental Protection Act 1990. In England and Wales, anyone who produces, carries, keeps, treats or disposes of controlled waste must take reasonable measures to stop it escaping, transfer it only to an authorised person and pass on a written description of it. The Scottish wording differs.

Householders in England and Wales must take reasonable steps to make sure their household waste goes only to an authorised person, and breaching the duty of care is a criminal offence. In England, the guidance also rules out a waste licensing exemption for using knotweed. Landfill, burial and burning are each subject to their own conditions.

Private nuisance

Two cases shape the law of private nuisance in England and Wales. In Network Rail v Williams (2018), the Court of Appeal held that knotweed rhizomes encroaching onto a neighbour's land are an actionable nuisance even without physical damage, where the owner knows or ought to know of the risk and fails to take reasonable steps. It also held that a fall in market value caused only by knotweed on neighbouring land is not, on its own, a nuisance.

In Davies v Bridgend County Borough Council (2024), the Supreme Court refused damages for a fall in value that had occurred before the council's breach began, because the breach did not cause that loss. Timing is therefore central to a claim against a neighbour.

Scotland

In Scotland, the Wildlife and Natural Environment (Scotland) Act 2011 replaced the list of named plants. Under the Scottish version of section 14, it is an offence to plant, or otherwise cause to grow, any plant in the wild "at a place outwith its native range". The change took full effect on 2 July 2012, when Schedule 9 was also repealed for Scotland.

A statutory Code of Practice on Non-Native Species has applied since the same date. Breaching the code is not an offence in itself, but compliance with it can be used as evidence in a prosecution. In October 2025, Environmental Standards Scotland concluded that the code was "not fit for purpose" and called for a review, and the Scottish Government accepted that it should be reviewed and updated. We had found no revised code as of 20 October 2026, so check for updates before relying on the 2012 version.

The CPN rules and nuisance cases above are England and Wales law, and Scottish nuisance law is not covered here.

Northern Ireland

Article 15(2) of the Wildlife (Northern Ireland) Order 1985 makes it an offence in Northern Ireland to plant or otherwise cause to grow in the wild any plant listed in Part II of Schedule 9, which includes Japanese knotweed. Article 15(2A) adds an offence of knowingly causing or permitting this. Penalties and disposal rules for Northern Ireland are not covered here, so take local advice.

In practice

Because the defences turn on whether you took reasonable steps, keep a dated record of what you do. Do not dig knotweed out and take it away without following the waste rules, and GOV.UK advises against treating it yourself unless you have the right skills and experience. A specialist can prepare a knotweed management plan to show that you are dealing with the problem.