JAPANESE KNOTWEED UK LAW: LEGAL GUIDE

OVERVIEW OF THE LAW

UK law establishes clear requirements regarding Japanese knotweed. Property owners must prevent its spread and properly dispose of plant material. This guide examines the key legislation and case law affecting property owners, buyers, sellers, and developers.

Laws

Wildlife and Countryside Act 1981: does not allow you to plant or cause knotweed to grow in the wild
Environmental Protection Act 1990: classifies Japanese knotweed as “controlled waste” and requires proper disposal
Anti-social Behaviour, Crime and Policing Act 2014: allows prosecution for not controlling knotweed on your property or allowing it to spread to your neighbour’s land
The Town & Country Planning Act 1974: Although having Knotweed in your garden isn’t illegal, not controlling its spread can get you into legal trouble.

Consequences and risk of prosecution

If you allow or cause Japanese Knotweed to spread in the wild, you can be prosecuted
If you have disposed of Japanese Knotweed incorrectly, you can be prosecuted. Japanese Knotweed is classed as controlled waste, requiring transport and disposal by registered waste carriers to be disposed at licensed landfill sites

Other

You can be sued for costs and damages if knotweed spreads to your neighbour’s property
Japanese knotweed can devalue your home significantly

Last updated: March 12, 2025

ABOUT US

Written and reviewed by: Lindsay Hardy, Managing Director, CSJK Certified and a Japanese Knotweed Expert. This guide represents the current legal landscape regarding Japanese knotweed in England and Wales as of March 2025. Our experts and the Law Firms that we work with Roach Pittis and DLG Legal Services, have over 100 years of combined experience in environmental law and Japanese knotweed remediation, having handled more than 500 knotweed-related legal cases and property transactions.

We’ve put together this page to help you understand exactly where you stand legally if you find Japanese Knotweed on your property. A question we get asked all the time by worried property owners: “Am I breaking the law by having knotweed on my land?” The short answer is no – it’s not illegal to have Japanese Knotweed on your property.

The problems start when it spreads next door, and you could be liable for expensive civil claims from your neighbours.

PROPERTY OWNERS RESPONSIBILITIES

Despite its notorious reputation, Japanese Knotweed is not a notifiable weed – something that surprises most of our clients. You don’t have to report it to the Environment Agency, but there are strict regulations around disposal and deliberate planting. Disposing of Japanese knotweed waste must be done in accordance with legal requirements to prevent its spread and avoid legal consequences. Property owners and waste carriers must ensure that knotweed waste is managed legally, using licensed landfills and registered waste carriers.

Our team is PCA-certified and has seen every type of knotweed scenario imaginable. We’ve developed solutions for everyone we’ve come across. We’ll help you identify Japanese Knotweed and explain why professional treatment far outperforms those DIY solutions.

It’s crucial to make a positive Japanese knotweed identification to ensure proper management and avoid potential legal repercussions.

LEGAL CONSEQUENCES OF NON-COMPLIANCE

WILDLIFE AND COUNTRYSIDE ACT 1981 (SECTION 14)

The Wildlife and Countryside Act 1981 (Section 14) establishes key legal requirements regarding Japanese knotweed:

Section 14(2) makes it illegal to “plant or otherwise cause to grow in the wild” Japanese knotweed and other invasive non-native species.
Penalties include fines up to £5,000 and/or up to 2 years imprisonment.
Property owners have a responsibility to prevent knotweed from spreading to natural habitats.
Recent enforcement has focused on those who negligently allow the spread to protected areas.

Read our complete guide to the Wildlife and Countryside Act.

ENVIRONMENTAL PROTECTION ACT 1990 (SECTIONS 33-34)

Under the Environmental Protection Act 1990 (Sections 33-34), Japanese knotweed is classified as “controlled waste” with specific legal requirements:

Japanese knotweed plant material and contaminated soil are classified as controlled waste under the Environmental Protection (Duty of Care) Regulations 1991
All waste containing Japanese knotweed must be accompanied by proper Waste Transfer Notes [Environment Agency Code of Practice, 2018]
Transportation requires a registered waste carrier license [Environmental Protection Act 1990, Section 34]
Disposal is restricted to licensed landfill sites with the appropriate permits [Hazardous Waste Regulations 2005]
Penalties include unlimited fines and up to 5 years imprisonment for improper disposal [Environmental Protection Act 1990, Section 33(8)]

Read our complete guide to the Environmental Protection Act.

TOWN AND COUNTRY PLANNING ACT 1990 (SECTION 215)

The Town and Country Planning Act 1990 (Section 215) has implications for Japanese knotweed management.

Although having Japanese knotweed growing in your garden isn’t illegal, not controlling its spread can get you into legal trouble. Councils can force you to clear up any Knotweed on your land if it affects the community, especially if it’s lowering the value of neighbouring properties. Additionally, you could face civil liability if it causes a nuisance to others.

The TCPA also affects development, as Planning Authorities often require the Knotweed to be cleared before development begins.

Many developers get stuck here—clearing the topsoil is not good enough.

Knotweed can regenerate from fragments as small as 0.7 grams, and contaminated material can cause ecological damage with legal consequences. You need to treat following PCA-approved protocols.

Read our complete guide to the Town and Country Planning Act.

ANTI-SOCIAL BEHAVIOUR, CRIME AND POLICING ACT 2014 (PART 4)

The Anti-Social Behaviour, Crime and Policing Act 2014 (Part 4) introduced measures that can address Japanese knotweed issues.

Part 4 of the Anti-social Behaviour, Crime and Policing Act introduced Community Protection Notices (CPNs) and Remedial Orders that can address Japanese Knotweed issues.

A CPN is a notice issued under the Anti-social Behaviour, Crime and Policing Act 2014 that requires an individual or body to stop conduct that is having a detrimental effect on the quality of life of those in the locality. It targets unreasonable, persistent or continuous behaviour that negatively affects local quality of life.

Section 57 defines “behaviour” as both actions and inactions. Therefore, a landowner persistently allowing Japanese Knotweed to spread can be grounds for a CPN if it negatively impacts the community’s quality of life. To effectively treat Japanese knotweed, it is crucial to use professional chemical treatments like glyphosate-based herbicides and adhere to legal disposal practices to prevent its spread.

Read our complete guide to the Anti-Social Behaviour, Crime and Policing Act 2014.

Professional Support: Our PCA-certified specialists provide comprehensive knotweed surveys and management plans that ensure legal compliance.

WE WORK EXCLUSIVELY WITH THE FOLLOWING SOLICITORS

LANDMARK LEGAL CASES: RECENT PRECEDENTS

The law surrounding Japanese Knotweed is constantly changing through major court cases. These precedents have shaped how the law is applied and interpreted:

Waistell vs. Network Rail (2017)

The case involved Mr Waistell, who owned property adjacent to land owned by Network Rail. Japanese knotweed was growing on Network Rail’s land near the boundary with Mr Waistell’s property. Even though the knotweed hadn’t physically crossed onto his land, Mr Waistell claimed that its presence still constituted a nuisance because of it:

Reduced the value of his property (the “stigma” effect)
This made it difficult for him to sell his property
Potentially threatened the structural integrity of his property in the future

In February 2017, Recorder Grubb ruled in favour of Mr Waistell at the Cardiff County Court. The key finding was that even without physical encroachment, knotweed on Network Rail’s land constituted an “actionable interference” with using and enjoying Mr Waistell’s property. Network Rail was found liable for a private nuisance.

Network Rail appealed the decision, but in July 2018, the Court of Appeal upheld the ruling (though on slightly different grounds). The Court of Appeal emphasized that the actionable nuisance was not merely the diminution in property value but the interference with the land’s amenity value – specifically, the owner’s ability to use and enjoy the property.

This case established an important precedent in UK property law by expanding the scope of a private nuisance to include situations where invasive plants on neighbouring land affect property values and marketability, even without physical encroachment. It placed greater responsibility on landowners to control Japanese knotweed when it could affect neighbouring properties.

According to Joseph Henry, Associate at Hodge Jones & Allen: “This decision also paves the way for disputes between individual owners of neighbouring properties.”

Williams v Network Rail (2017)

The Williams case involved Mr Williams and Mr Waistell, who owned properties adjacent to Network Rail land in South Wales, where Japanese knotweed was growing. The cases were initially heard separately but were joined for the appeal.

In the Court of Appeal ruling, Sir Terence Etherton, the Master of the Rolls, clarified the legal reasoning. While the county court had found for the claimants based partly on diminution of property value (pure economic loss), the Court of Appeal took a different approach. The court rejected the pure economic loss argument, stating that nuisance claims cannot be based solely on a reduction in property value.

However, the court upheld the finding of nuisance on different grounds – that the presence of Japanese knotweed represented an interference with the “amenity value” of the claimants’ properties. The court found that knotweed imposed a burden on landowners by impeding their ability to use and enjoy their land fully, particularly with regard to development potential.

The Williams case, together with Waistell, established that knotweed within 7 meters of a property boundary could constitute an actionable nuisance even without physical damage or encroachment, based on its impact on the practical use and enjoyment of the property rather than just economic considerations.

JMP Solicitors state: “Network Rail have admitted to their failings in dealing with this pernicious weed and the injunction we brought to make them deal with the problem has been agreed with by the Court of Appeal.This is a significant case for local authorities, land-owners and private home owners alike.

This ruling has had significant implications for property owners. It has led to numerous subsequent knotweed claims against landowners who failed to control Japanese knotweed near neighbouring properties.

Ryb v Conway Chartered Surveyors (2019)

This professional negligence case resulted in a surveyor being found liable for not identifying Japanese Knotweed during a pre-purchase survey. The court awarded the buyer £50,000 in damages, making it clear that surveyors have a duty of care to find Japanese Knotweed during property inspections. This case highlights the importance of knotweed surveys during property transactions.

Davies & Another v Bridgend County Borough Council (2023)

This recent case found local authority liability for knotweed encroachment from council-owned land. The court found the council had failed in its duty of care to prevent Japanese Knotweed from spreading, setting an important precedent for public body accountability for Japanese Knotweed on public land.

CIVIL LAW AND JAPANESE KNOTWEED: UNDERSTANDING THE LEGAL IMPLICATIONS

Japanese knotweed laws impose serious legal responsibilities on homeowners to control its growth and prevent its spread. Non-compliance with these regulations can result in significant penalties. It brings serious legal implications for everyone connected to affected properties – neighbours, landlords, tenants, buyers and sellers alike.

It is crucial to remove Japanese Knotweed thoroughly to prevent regrowth and avoid legal complications, as contaminated soil or plant material must be managed carefully to prevent ecological harm and legal consequences. At Knotweed Services (UK) Ltd, we offer complete guidance on professional treatment options to protect your interests.

ENCROACHMENT

Encroachment in this scenario is defined as: when Japanese knotweed physically crosses a boundary onto neighbouring land.

If Japanese Knotweed on your land spreads to a neighbour’s property, you could be pursued under common law nuisance principles. These require landowners to take reasonable steps to prevent issues on their land from affecting adjacent properties, i.e., preventing Japanese Knotweed from spreading.

Liability kicks in when you’ve been notified or should have reasonably known about the knotweed issue. But if you caused Japanese Knotweed to be introduced and then spread to a neighbour’s land, you could be strictly liable even if you’d taken steps to prevent it.

Any successful claim for Japanese knotweed compensation from legal action would likely seek damages for the cost of treatment and possibly a court order to make you undertake the removal.

The landlord-tenant situation adds to the complexity. Depending on the terms of the lease and when the Knotweed originated, tenants could find themselves responsible for knotweed treatment costs.

MISREPRESENTATION

Let’s look at misrepresentation and define what it is: A false statement of fact that induces someone to enter a contract, potentially making the contract voidable.

Can be:

Fraudulent misrepresentation: When a seller knowingly makes a false statement
Negligent misrepresentation: When a seller makes a statement without reasonable grounds to believe it’s true

When a seller lies about Japanese Knotweed, it affects a buyer’s decision and causes financial loss.

Properly identifying and disclosing the presence of invasive non-native plants when selling a property is key to avoiding legal issues during the transaction.

The Law Society’s Property Information Form (TA6) covers this in question 7.8: “Is the property affected by Japanese knotweed?” Sellers must answer ‘Yes’, ‘No’ or ‘Not known’.

A seller knowingly answering ‘No’ or ‘Not known’ when they know of Knotweed could be liable for fraudulent misrepresentation or negligent misrepresentation might apply if the seller:

Should have reasonably known about the Knotweed
Didn’t investigate their suspicions
Answered ‘No’ without reasonable grounds
Noted unusual growth but didn’t properly identify it before completing TA6

BOUNDARIES AND PARTY WALL CONSIDERATIONS

Knotweed often creates complex legal situations when it crosses property boundaries. Here’s what you need to know:

Party Wall Act Implications

When Knotweed affects party walls or shared boundaries, the Party Wall Act 1996 may apply. This requires:

Proper notification to adjoining owners before treatment that affects shared structures
Potential party wall agreements for remediation work
Professional surveys to document the extent of growth and required treatment

Shared Responsibility Scenarios

Courts are now recognising that boundary knotweed requires joint treatment. In these cases:

Costs will be apportioned by the extent of the infestation
Joint management plans will be required
Legal agreements to confirm shared responsibilities are needed

Boundary Disputes

Knotweed causes boundary disputes when:

The source of infestation is unknown
Boundaries are unclear
Spread has occurred over many years

In these cases, professional boundary determination may be needed before liability can be established. We can provide **CPR 35-compliant expert witness services to help resolve these disputes.

**CPR 35-compliant:** Refers to expert witness reports that comply with Part 35 of the Civil Procedure Rules, which govern how expert evidence is presented in civil court cases in England and Wales.

BUT WHAT IF I MISS JAPANESE KNOTWEED?

Don't worry; we can conduct a Japanese knotweed site survey to find Japanese Knotweed or suspect growth.

We would highly recommend that anybody buying a house or selling a property with Japanese Knotweed has a Japanese knotweed survey. It prevents later compensation or misrepresentation claims for sellers and ensures the sale goes through fairly swiftly.

Not declaring Japanese Knotweed has, in our experience, only caused problems. We have seen cases where purchases have been seriously delayed and, in some cases, even cancelled.

BUYING AND SELLING PROPERTY

As we have discussed, having Japanese Knotweed on your property can cause problems for those trying to sell your property and for buyers trying to secure mortgage finance.

TA6 Form: The Law Society’s Property Information Form used in residential property transactions that requires disclosure of Japanese knotweed.

SELLERS

It is your legal obligation when selling a property with Japanese Knotweed to disclose if you have Japanese Knotweed in your garden on the TA6 form.

You will also be asked to include a knotweed management plan if you have one in place. If you don’t declare it, many lenders will still ask for a site survey and report.

BUYERS

If Japanese Knotweed is present, it must be declared on the TA6 form. Mortgage lenders won’t proceed without a professional management plan backed by an insurance-backed guarantee.

If you think the seller lied about Japanese Knotweed on their TA6, get legal advice straight away – you may be able to pursue a case for misrepresentation.

LEGAL PROTECTION FOR BUYERS

When buying a house with Japanese Knotweed, specific legal protections can safeguard your investment:

PRE-PURCHASE CONTRACTUAL PROTECTIONS

Savvy buyers should consider:

Specific knotweed warranties in the purchase contract
Retention clauses holding back funds pending treatment
Special condition clauses requiring professional remediation
Indemnity insurance against undisclosed infestations

PRE-PURCHASE
SURVEYS

For legal protection, buyers should:

Commission specialist knotweed surveys (not just standard building surveys)
Ensure surveyors have specific professional indemnity insurance for Knotweed
Document the condition with dated photographs
Retain all correspondence regarding knotweed discussions

POST-PURCHASE
LEGAL REMEDIES

If you’ve found Japanese Knotweed after purchase, buyers may have recourse through:

Misrepresentation claims (must be brought within 6 years)
Professional negligence claims against surveyors (subject to different limitation periods)
Breach of contract claims where specific warranties were provided
Nuisance claims against neighbouring properties if encroachment occurs

We can connect buyers with specialist solicitors experienced in knotweed litigation to protect their interests.

NEIGHBOUR DISPUTES

Property owners have a legal duty to prevent Japanese Knotweed from growing on their land and spreading to adjacent properties. Local councils can serve Community Protection Notices (CPNs) to homeowners who allow it to spread and take court action if ignored.

Suppose you see Knotweed on your neighbour’s land. In that case, we recommend talking to them first before reporting Japanese Knotweed to local authorities. Addressing the knotweed issue amicably usually works out best for everyone.

PRACTICAL CHECKLIST: SELLING A PROPERTY WITH JAPANESE KNOTWEED

MORTGAGE CONSIDERATIONS

COMMERCIAL PROPERTY CONSIDERATIONS

Commercial property owners face distinct legal challenges regarding Knotweed.

COMMERCIAL LANDLORD OBLIGATIONS

Commercial landlords must:

Meet specific disclosure requirements in commercial leases
Include Knotweed in pre-lease environmental surveys
Consider specific lease clauses addressing management responsibilities
Maintain appropriate commercial premises liability insurance

IMPACT ON COMMERCIAL LEASES

Knotweed infestations can affect:

Rent reviews and lease renewals
Dilapidations claims
Service charge arrangements
Tenant improvement works requiring ground disturbance

BUSINESS LIABILITY CONSIDERATIONS

Commercial operators should be aware of the following:

Potential business interruption from required treatment
Environmental liability for contaminated soil removal
Regulatory compliance requirements for industrial sites
Disclosure obligations during business property transactions

Our commercial property specialists can develop bespoke management plans that minimise business disruption while ensuring full legal compliance.

PLANNING PERMISSION REQUIREMENTS

Development sites with Japanese Knotweed require:

Detailed knotweed management plans as part of planning applications
Pre-development knotweed surveys and mapping
Specific conditions for treatment before groundworks begin
Monitoring provisions throughout the development process
Method statements for soil management and waste disposal

SITE SURVEY OBLIGATIONS

Developers must undertake:

Comprehensive knotweed surveys by PCA-registered specialists
Rhizome mapping to determine excavation requirements
Soil testing to determine contamination boundaries
Historical investigations to identify previous treatment attempts
Risk assessments for potential spread during development

ENVIRONMENTAL IMPACT ASSESSMENTS

For larger developments, knotweed considerations include:

Inclusion in formal Environmental Impact Assessments
Biodiversity net gain calculations accounting for knotweed removal
Sustainable disposal strategies
Long-term site management commitments
Monitoring regimes extending beyond completion

WHAT ARE THE IMPLICATIONS FOR DEVELOPMENT LAND?

Japanese Knotweed creates significant legal challenges for land developers.

Our development specialists can create phased management plans that integrate with construction schedules while ensuring full regulatory compliance.

FAQs

Am I breaking the law by having Japanese knotweed on my property?

No, it is not illegal to have Japanese knotweed on your property. However, you have legal obligations to:

Prevent it from spreading to neighbouring properties
Dispose of knotweed waste properly through licensed waste carriers
Disclose its presence when selling your property

Do I have to report Japanese knotweed to authorities?

No, Japanese knotweed is not a notifiable plant in the UK. You are not legally required to report it to the Environment Agency or local authorities. However, you must manage it responsibly. Click here to find out more.

How much can Japanese knotweed devalue my property?

According to RICS research (2022), Japanese knotweed can reduce property values by 5-15% depending on the severity of the infestation and proximity to structures. Some mortgage lenders may refuse lending entirely without a professional management plan.

What exactly must I disclose when selling my property?

When selling a property in England and Wales, you must accurately complete question 7.8 on the TA6 Property Information Form: “Is the property affected by Japanese knotweed?” Options are ‘Yes’, ‘No’ or ‘Not known’. If ‘Yes’, you must provide a management plan and survey.