The complete Japanese knotweed legal guide

Environet has been a specialist in Japanese knotweed for over 25 years. We are seen as a leading authority on Japanese knotweed and are often called upon to give expert testimony in legal cases. If you are looking to understand your legal obligations for Japanese knotweed, this is the guide for you.

We are often asked by worried customers whether they are breaking the law by having Japanese knotweed growing on their land. The straightforward answer is no, but if you allow it to encroach onto a neighbouring property, then you are leaving yourself wide open to civil prosecution that could become very expensive indeed. There is various legislation in place that regulates and controls the disposal and planting of knotweed, but people are often surprised to learn that it is not an offence to have knotweed on your land and it is not a notifiable weed, therefore the local authorities do not need to be told of its presence.

Quick facts

Who is responsible for knotweed?

  • The responsibility for controlling Japanese knotweed always lies with the landowner.


  • The Environment Agency, Scottish Environment Protection Agency, Natural Resources Wales or the Northern Ireland, Environment Agency are responsible for regulating waste. They are also responsible for granting permission to apply chemicals in protected areas such as SSSI and near water courses. These statutory bodies are not responsible for controlling invasive non-native species, other than those plants growing on land in their ownership/ stewardship. Managing such species is the responsibility of the owner/occupier of a site.


  • Where Japanese knotweed is growing near your boundary (within 3m), it will usually impact your ability to sell or mortgage your house. You should therefore write to the adjoining landowner to request action. If you are unable to find out who owns the land in question, you may be able to find the information by carrying out a land registry search.
Knotweed encroachment on a residential site

What is the law regarding Japanese knotweed?

There are several pieces of criminal and civil legislation relating to Japanese knotweed.

Criminal Law

Japanese knotweed is listed in Schedule 9, Part II of the Wildlife and Countryside Act 1981. Section 14(2) of the Wildlife and Countryside Act (WCA) 1981 states that, “if any person plants or otherwise causes to grow in the wild any plant which is included in Part II of Schedule 9, he shall be guilty of an offence”.

Both the Police and local authorities have enforcement functions under the Act. Penalties for a Section 14 offence have been modified by the Countryside and Rights of Way Act 2000 for England and Wales. A magistrates’ court can impose a maximum fine of £5,000 or a maximum prison sentence of six months, or both. A Crown Court can impose an unlimited fine or indictment or a maximum prison sentence of two years, or both.

Any soil and waste containing propagules of a plant species listed in Schedule 9 of the Wildlife and Countryside Act 1981 (as amended) that you discard, intend to discard or are required to discard are considered to have the potential to cause ecological harm and hence deemed “Controlled Waste‟ or “Directive Waste‟ (Waste Management Licensing Regulations (WMLR) 1994 as amended).

The most relevant provisions are in Section 33 (1a) and (1b) which create offences to do with the depositing, treating, keeping or disposing of controlled waste without a licence. The possible sentence for a breach of s33(1)(a) depends on whether your matter is dealt with by the Magistrates’ Court or the Crown Court.

If your case is dealt with by the Magistrates’ Court, you may be liable to a sentence ranging from a fine (up to an unlimited value) to imprisonment for 12 months. If the Crown Court deals with your case, the possible sentences range from a fine (up to an unlimited value), to imprisonment for 5 years.

There are powers under the Town & Country Planning Act section 215 for Local Authorities to force landowners to clear up land if it detracts from local amenities, including that infested by Japanese knotweed. The Town & Country Planning Act is also often used by Local Planning Authorities by way of planning conditions to ensure developers properly remediate sites infested with knotweed.

Part 4 of the Act introduced Community Protection Notices and Remedial Orders. The community protection notice can be used against individuals who are acting unreasonably and who persistently or continually act in a way that has a detrimental effect on the quality of life of those in the locality. The Anti-social Behaviour, Crime and Policing Act 2014 does not explicitly refer to Japanese knotweed or other, similar invasive non-native plants, as the powers are intended to be flexible. However, frontline professionals can stop or prevent any behaviour that meets the legal test in the powers.

The notice can be used to require someone to control or prevent the growth of Japanese knotweed or other plants that are capable of causing serious problems to communities. The test is that the conduct of the individual or body is having a detrimental effect of a persistent or continuing nature on the quality of life of those in the locality, and that the conduct is unreasonable. Under section 57 of the Act, “conduct” includes “a failure to act”.

The Infrastructure Act 2015 gives environmental authorities in England and Wales the power to issue species control orders. These orders will make it possible to compel land owners or occupiers to carry out control or eradication operations, or allow them to be carried out by the issuing authority.

Breaching a species control order will be a criminal offence, but owners or occupiers will have the right to appeal to a tribunal and, where relevant, may be compensated for any damage caused by the eradication work.

Civil law

The presence of Japanese knotweed can have legal implications and consequences for neighbours, landlords, tenants, buyers and sellers of land and houses.

In the case of Japanese knotweed spreading from one owner’s land to a neighbour’s land the landowner could face a legal claim by the neighbour. This is because under the common law of nuisance a landowner must take reasonable steps to prevent a nuisance which may cause damage spreading from his land to neighbouring land. Generally, liability will only arise after the owner has been made aware or should have reasonably been aware of the problem. However, there is a legal argument which could be made to suggest that where the Japanese knotweed has been brought on to the land by the landowner and spreads to the neighbouring land he has a strict liability to his neighbour irrespective of whether the steps he has taken to prevent it from spreading have been reasonable or not.

In either case, the claim is likely to be for damages for the cost of eradicating it from the neighbouring land and/or an injunction forcing the landowner to take steps in regard to its treatment.

In the case of landlords and tenants, depending on the wording of the lease and also whether the Japanese knotweed was present when the lease was entered into, a tenant may find himself unwittingly liable to his landlord under the terms of his lease to have any Japanese knotweed on the demised property treated or removed.


In February 2016, in the landmark case Waistell vs, Network Rail – Recorder Grubb found that Mr Waistell had successfully made out his claim in private nuisance against Network Rail. It was found that not only had Mr Waistell’s property suffered from encroachment, but also that the mere presence of knotweed on Network Rail’s land was an actionable interference with the use and enjoyment of Mr Waistell’s land. As a result, Mr Waistell was awarded damages for the cost of treatment and the residual diminution in value of his property after the treatment had been carried out.

The case is significant as it holds big landowners to account and imposes a positive duty on them to ensure that any knotweed that is on their property is not preventing neighbouring landowners from being able to sell their property for market value. Failing to comply with this obligation will result in awards for damage for the cost of treatment of the knotweed and any residual diminution of value.

In this context, a misrepresentation is a false statement of fact (relating to the presence of knotweed) made by the seller to the purchaser, which induces them into purchasing the property and causes them to sustain a loss.  It does not need to be the only factor which induced the sale.

The starting point is ‘The Law Society’s Property Information Form’ (TA6) question 7.8.  This requires the seller to say whether the property is affected by knotweed and specifically asks:

“Is the property affected by Japanese knotweed?”

The seller then has the following tick box options available; ‘Yes’, ‘No’ or ‘Not known’.

If the seller ticks either ‘No’ or ‘Not known’ to this question but they did in fact know of the presence of knotweed on the property then it is likely that they have committed a fraudulent misrepresentation. 

If they ought to have known about the presence of the knotweed or ticked ‘No’ and had no reasonable grounds for believing that the property was not affected by knotweed then it is likely that they have  committed  a negligent misrepresentation.  An example of negligent misrepresentation would be where the seller knew a plant was growing in the garden but took no steps to seek to identify it prior to completing the TA6.

Japanese knotweed encroachment on a residential site

Can I sue my neighbour for Japanese knotweed?

The legal remedy for knotweed spreading onto your land from adjoining land can be found in civil nuisance. To bring a successful claim, the claimant needs to demonstrate that the knotweed originated from the adjoining land, and that the knotweed is causing the claimant owner “nuisance”.

  • It’s not always easy to prove the knotweed origin, but an expert should be able to give an opinion based upon “the balance of probabilities”, the test required in a civil case. A site survey should be able to identify this.


  • If the adjoining landowner, the defendant, is seen to be taking reasonable steps to mitigate the nuisance that may in itself be a suitable defence, making any claim likely to fail. However, we often see steps being taken that are not reasonable e.g. long treatment programmes and restrictions on use of the garden/property whilst the lengthy treatment programme is carried out.


  • If you think you are a victim of encroachment please talk to us. We can help you. One of our experts can provide Japanese knotweed expert witness services in accordance Civil Procedure Rules (CPR 35). We can also put you in touch with lawyers, highly experienced in Japanese knotweed disputes.

Do you have to disclose Japanese Knotweed?

If you find Japanese knotweed on your property, there is no need to inform any statutory body, or local authority.

However, when you come to sell a property you will be required to answer a set of pre-contract enquiries which typically follow the Law Society’s TA6 Form. This form has a specific question relating to Japanese knotweed, that you must answer truthfully and is phrased: “Is the property, or an area adjacent to or abutting the boundary, affected by Japanese knotweed? ” You can answer “Yes”, “No” or “Not known”;

  • The definition of “affected” has historically been a grey area, but in 2020, the Law Society published revised guidance to sellers. It states, if sellers choose to answer “No” (the property is not affected by Japanese knotweed) they must be certain (Law Society emphasis) that no rhizome (root) is present in the ground of the property, or within 3m of the property boundary, even if there are no visible signs above ground.
  • Due to the nature of knotweed it is almost impossible to be certain that no rhizome is present, so often the safe bet is to answer “Not known”, except of course where the answer should be “Yes”.
    1. that they know what knotweed is, and
    2. that they have taken positive steps to satisfy themselves that it is not present on the property.

If it can be proved that knotweed was present at the time of sale and that the seller knew of its presence, or ought to have known of it, then it is likely that the purchaser will have a strong claim against the seller for misrepresentation.

TA6 form

Is knotweed reportable?

As it is not an offence for someone to have Japanese knotweed on their land, there is no requirement for it to be reported. However, you can help in the fight against Japanese knotweed by reporting any sightings on our Japanese knotweed Heatmap, Exposed™. The map has already been populated with thousands of infestations through our own historical records and new verified sightings, which are uploaded and verified by our team daily.

By reporting Japanese knotweed, you are helping to provide a picture of the distribution of Japanese knotweed, which in turn allows us to define which areas are at greater risk of being affected. This is useful for;

  • Homebuyers who might decide to instruct a Japanese knotweed Survey on a property they are interested in, where the risk in the local area has been identified as medium or high.
  • Property professionals involved in house transactions such as chartered surveyors, conveyancing solicitors and estate agents, who can provide better advise to their clients using the data.
  • Developers and contractors, who are looking at buying land, where again they are recommended to instruct a pre-purchase survey to check for Japanese knotweed.

Is Japanese knotweed notifiable in the UK?

Contrary to popular belief Japanese knotweed is not a notifiable weed, , in fact, the entire concept of “notifiable weeds” is a complete myth. There is no legal requirement to report the presence of any plant on land you own or control to the Authorities.

The concept of “notifiable weeds” is derived from the Weeds Act 1959, which lists 5 plant species that were considered injurious where they were allowed to grow, uncontrolled in, or in close proximity to pasture land. These are:

  • Common Ragwort.
  • Broad-Leaved Dock.
  • Curled Dock.
  • Creeping Thistle.
  • Spear Thistle.


The Act does not make controlling the plants compulsory for landowners or occupiers. Nor does it prohibit anyone from growing them, and it does not make possession of any of those plants a criminal offence.

Can I claim compensation for Japanese knotweed?

Being able to claim compensation for Japanese knotweed depends greatly on the given situation. Having a Japanese knotweed survey completed will ascertain a number of potential factors that may make a claim feasible. These situations could be that Japanese knotweed has encroached onto your property within the last few years. You’ve bought a house where you’ve found Japanese knotweed present though weren’t made aware of it during the sale or it wasn’t included on a surveyor’s report.

Costs can be recovered for the eradication of Japanese knotweed and associated insurance backed guarantee, any diminution of value to the property as a result of the Japanese knotweed and any consequential losses.

Is knotweed illegal?

There are many laws surrounding knotweed, which can be confusing.

Japanese knotweed is not a notifiable weed nor is it illegal to have it growing on your property as long you don’t allow it to spread onto adjoining land. If this happens, either a civil nuisance claim can be brought against you for allowing the knotweed to encroach onto private land, or you may be committing a criminal offence under the Wildlife and Countryside Act 1981 if you have caused Japanese knotweed to grow in the wild. 

As Japanese knotweed is also identified as a “Controlled Waste” under the Environmental Protection Act 1991, it is also illegal to dispose of any viable Japanese knotweed plant material (roots, greenery, or soil) without the appropriate licence.

Key do’s and don’ts with Japanese knotweed to avoid breaking the law:

  • Make certain that any site or property is thoroughly inspected prior to any purchase or disturbance works taking place.


  • Ensure any Japanese knotweed documentation is kept on file, up to date and made available to involved parties.


  • Make sure that any Japanese knotweed is not allowed to spread into the wild or neighbouring properties.


  •  If you believe that knotweed is spreading from neighbouring land into your property/land then have a reputable company attend to inspect and provide guidance.


  •  Do not attempt to sell land or property where Japanese knotweed has been purposely concealed.


  •  Do not dispose of Japanese knotweed into household or green waste collections. A licenced contractor must dispose of the waste and provide waste transfer slips.
Knotweed next to a river

Is having Japanese knotweed a criminal offence?

Having Japanese knotweed in your possession or growing it on your land is not a criminal offence, however you would be committing a criminal offence in the following circumstances:

  • Allowing Japanese knotweed to knowingly spread into the wild or neighbouring property. You may be committing a criminal offence under the Wildlife and Countryside Act 1981 if you have caused Japanese knotweed to grow in the wild.


  • By not disposing of viable Japanese knotweed material (controlled waste) through a Environet Agency registered waste carrier via a licensed landfill site. Environmental Protection Act 1990 includes provisions including a “duty of care” for the storage, processing, treating and disposal of controlled waste. Japanese knotweed and the soils it infests are considered to be a controlled waste.

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