TA6 Japanese Knotweed: What to Disclose
What you need to declare about Japanese knotweed on the TA6 Property Information Form, including current infestations, treated knotweed, and knotweed on neighbouring land.
What you need to know
When completing the TA6 Property Information Form, sellers must disclose any Japanese knotweed on the property or neighbouring land that they are aware of, including infestations that have been professionally treated. Section 7.8 of the form asks directly about knotweed, and failing to answer honestly can result in a misrepresentation claim after completion.
- Section 7.8 of the TA6 form specifically asks about Japanese knotweed — you must answer honestly, even if the knotweed has been treated.
- Treated knotweed still requires disclosure, along with the treatment plan, progress reports, and insurance-backed guarantee.
- You must disclose knotweed on neighbouring land if you are aware of it, especially if it falls within the seven-metre RICS boundary zone.
- Deliberately concealing knotweed can result in a misrepresentation claim under the Misrepresentation Act 1967, with damages or rescission of the sale.
- Providing full documentation upfront reduces buyer solicitor enquiries and keeps the sale on track.
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Check your sale readinessJapanese knotweed is one of the most contentious issues in UK residential property sales. For sellers completing the TA6 Property Information Form, knowing exactly what to disclose about knotweed — whether it is currently growing, has been treated in the past, or is present on a neighbouring property — is essential. Getting this wrong can delay your sale, collapse the transaction, or expose you to legal action after completion.
This guide explains what Section 7.8 of the TA6 asks, what constitutes a proper disclosure, and how to present knotweed information in a way that keeps your sale moving. It also covers the specific scenarios that sellers most commonly find difficult: treated infestations, neighbouring knotweed, and situations where you are genuinely uncertain.
What Section 7.8 of the TA6 asks about Japanese knotweed
The TA6 Property Information Form is a detailed questionnaire about your property that gets sent to the buyer's solicitor as part of the conveyancing process. Section 7 covers environmental matters, and Question 7.8 specifically asks whether the property is affected by Japanese knotweed. The question is designed to capture three scenarios:
- Knotweed currently growing on the property — Active Japanese knotweed on any part of your land, whether in the garden, along boundaries, or in outbuildings and hard-standing areas.
- Knotweed that has been treated or eradicated — A past infestation that has been professionally treated, even if there is no longer any visible growth above ground.
- Knotweed on neighbouring or adjacent land — Japanese knotweed on a neighbouring property that you are aware of, particularly if it is within seven metres of your boundary.
You are asked to respond with ‘Yes’, ‘No’, or ‘Not known’. If your answer is ‘Yes’, you are expected to provide additional information, including the location of the knotweed, whether it has been treated, and what documentation is available. Understanding the scope of this question is the first step to completing your property information form accurately.
Disclosing current Japanese knotweed on your property
If Japanese knotweed is currently growing on your property, you must answer ‘Yes’ to Section 7.8 and provide details. This is the most straightforward scenario, and there is no ambiguity: active knotweed must be disclosed. The key is not just acknowledging it but providing enough information for the buyer and their solicitor to assess the situation.
Your disclosure should include:
- The approximate location of the knotweed on the property (for example, along the rear boundary, in the side garden, or near the driveway).
- Whether a professional survey has been carried out, and if so, the RICS risk categorisation (Category A, B, C, or D).
- Whether a treatment programme is underway, including the name of the PCA-accredited contractor, the treatment method, and the current stage of the programme.
- Whether an insurance-backed guarantee has been issued, or when one is expected to be available.
If you have not yet arranged treatment, you should explain this and indicate your plans. Untreated knotweed with no management plan is the scenario most likely to cause problems with the buyer's mortgage lender. For a broader understanding of how knotweed affects property sales, see our guide on Japanese knotweed and selling your property.
Disclosing treated or eradicated knotweed
A common mistake sellers make is assuming that because Japanese knotweed has been treated and is no longer visible, they do not need to mention it on the TA6. This is wrong, and it is one of the most common TA6 mistakes. Treated knotweed still requires full disclosure.
The reason is straightforward: the rhizome system of Japanese knotweed can survive underground for up to 20 years, and even after a successful herbicide programme, there is a residual risk of regrowth. This is precisely why treatment contractors issue insurance-backed guarantees — to cover the buyer and their lender against the possibility that the knotweed returns. If you omit the treatment history and the buyer later discovers evidence of a past infestation — through old photographs, contractor records, or regrowth — you could face a misrepresentation claim.
When disclosing treated knotweed, your answer to Section 7.8 should include:
- The date the infestation was first identified and by whom (for example, a PCA-accredited surveyor or your own observation).
- The treatment method used (herbicide application, excavation, or a combination).
- The name and PCA accreditation number of the contractor who carried out the treatment.
- The start and end dates of the treatment programme, including how many seasons of herbicide were applied.
- Details of the insurance-backed guarantee, including the insurer, the guarantee period (usually a minimum of 10 years), and the guarantee number.
Far from being a negative, presenting a comprehensive treatment history with an insurance-backed guarantee actually reassures buyers and their solicitors. It demonstrates that the issue has been managed professionally and that financial protection is in place. This is far better than a blank or evasive answer that triggers additional enquiries and suspicion.
Disclosing knotweed on neighbouring land
Your disclosure obligation extends beyond your own property boundary. If you are aware that Japanese knotweed is growing on a neighbouring property, you should disclose this on the TA6 form. The RICS categorisation system recognises knotweed within seven metres of a property boundary as a material risk factor (Category B), so neighbouring infestations in this zone are directly relevant to the buyer and their mortgage lender.
You are not expected to survey your neighbours' land or hire a specialist to inspect adjacent properties. Your obligation is to disclose what you actually know. For example:
- You have seen knotweed growing in a neighbour's garden or along a shared boundary.
- A neighbour has told you about a knotweed problem on their land.
- You have received correspondence from the local authority about knotweed in the area.
- A previous treatment contractor or surveyor mentioned neighbouring knotweed during their inspection of your property.
When disclosing neighbouring knotweed, note the approximate location relative to your boundary and whether you are aware of any treatment being carried out by the neighbour. If you have discussed the issue with your neighbour and they have confirmed they have a treatment plan in place, include this information. If you have had no contact with the neighbour about the issue, say so — the buyer's solicitor may raise enquiries with the neighbouring property owner directly.
It is worth understanding your broader duty of disclosure as a UK seller to ensure you are meeting all your obligations, not just those relating to knotweed.
When you genuinely do not know
There are legitimate situations where a seller does not know whether Japanese knotweed is or has been present. You may have purchased the property recently and have no knowledge of its history, or you may live in an area where knotweed is not common and have never had reason to investigate. In these cases, answering ‘Not known’ to Section 7.8 is appropriate.
However, ‘Not known’ must be a genuine statement, not a convenient way to avoid an uncomfortable disclosure. If you have any reason to suspect knotweed — unusual plant growth, comments from neighbours, a previous survey that mentioned it, or treatment records left by a prior owner — you cannot honestly answer ‘Not known’. The concept of ‘wilful blindness’ applies: if you have chosen not to investigate something you have reason to believe exists, this may be treated as dishonesty by a court.
If you are unsure, the safest approach is to explain what you know and what you do not. For example: ‘We are not aware of Japanese knotweed on the property but have not commissioned a specialist survey. We have noticed some unusual plant growth along the rear boundary but have not had it identified.’ This kind of honest, qualified answer protects you far better than a flat ‘Not known’ that later turns out to be misleading. For more on the consequences of dishonest answers, see our guide on what happens if you lie on the TA6.
What documentation to provide
The strength of your TA6 knotweed disclosure depends heavily on the supporting documentation you provide. A well-documented disclosure reassures the buyer and their solicitor, reduces follow-up enquiries, and gives the buyer's mortgage lender the information they need to make a lending decision. You should aim to provide:
| Document | Purpose |
|---|---|
| Specialist knotweed survey report | Confirms the identification, extent of the infestation, and RICS risk categorisation |
| Treatment plan | Details the proposed or completed treatment method, timescales, and contractor credentials |
| Progress reports | Shows each treatment visit, observations, and herbicide applications over the treatment programme |
| Insurance-backed guarantee | The single most important document for mortgage lenders; typically covers a minimum of 10 years |
| Waste transfer notes (if excavation was used) | Proves that knotweed-contaminated soil was disposed of legally at a licensed landfill |
| Site photographs | Visual record of the infestation before, during, and after treatment |
Collating these documents into a single knotweed information pack and providing it to your solicitor before marketing the property is one of the most effective things you can do to prevent delays. The buyer's solicitor will inevitably request this information, so having it ready from day one keeps the transaction moving.
The legal consequences of non-disclosure
Failing to disclose known Japanese knotweed on the TA6 form is treated as misrepresentation. The legal framework that protects buyers in this situation is well established:
- Misrepresentation Act 1967 — If a buyer can show that your false or misleading TA6 answer induced them to enter the contract, they can claim damages. For fraudulent misrepresentation (deliberate concealment), there is no cap on damages. For negligent misrepresentation (carelessness), the burden shifts to you to prove you had reasonable grounds for your answer.
- Consumer Protection from Unfair Trading Regulations 2008 — If your estate agent markets the property as free from knotweed when they know otherwise, both you and the agent could face legal consequences.
- Limitation Act 1980 — The buyer has six years from completion to bring a misrepresentation claim. For fraudulent concealment, the six-year period starts from the date the buyer discovers (or ought reasonably to have discovered) the misrepresentation.
There have been several reported cases in England and Wales where buyers have successfully sued sellers for concealing Japanese knotweed. In Ryb v Conyers (2021), the court awarded substantial damages to a buyer who discovered knotweed that the seller had deliberately concealed. These cases serve as a clear warning: the risk of non-disclosure is far greater than the risk of honest disclosure.
How knotweed disclosure interacts with environmental searches
Buyers' solicitors routinely order environmental searches as part of the conveyancing process. Some environmental search products include checks against databases of known Japanese knotweed infestations, such as the Environet knotweed heat map or local authority records. If knotweed is flagged in the environmental search results, the buyer's solicitor will cross-reference this against your TA6 answers.
This creates a significant risk for sellers who fail to disclose. If the environmental search reveals knotweed that you did not mention on the TA6, the buyer's solicitor will raise immediate enquiries, and the inconsistency will undermine your credibility. At best, this delays the sale while additional investigations are carried out. At worst, the buyer loses confidence and withdraws.
Conversely, if your TA6 disclosure aligns with the environmental search results and you have provided comprehensive supporting documentation, the buyer's solicitor is likely to be satisfied that the issue is being managed. Consistency between your disclosure and the search results builds trust and reduces the likelihood of protracted negotiations.
Practical tips for a strong knotweed disclosure
Based on common enquiry patterns and the issues that cause the most delays, here are the practical steps that make the biggest difference:
1. Commission a specialist survey before listing
A PCA-accredited knotweed survey (typically £250 to £500) gives you an objective assessment of the infestation and a RICS risk categorisation. This is far more credible than a self-assessment and gives the buyer's lender the professional opinion they need.
2. Start treatment as early as possible
Herbicide treatment is seasonal (April to October), so plan ahead. A property with a completed or well-advanced treatment programme and an insurance-backed guarantee is in a far stronger position than one where treatment has only just begun. If you are planning to sell within the next year or two, starting treatment now can make the difference between a smooth sale and a protracted one.
3. Be specific in your TA6 answer
Do not simply tick ‘Yes’ and leave it at that. Provide a written explanation covering the location of the knotweed, the treatment history, and the documents available. A detailed answer reduces the number of follow-up enquiries the buyer's solicitor needs to raise.
4. Prepare a knotweed information pack
Gather all documentation — survey report, treatment plan, progress reports, insurance-backed guarantee, waste transfer notes, and photographs — into a single pack. Provide this to your solicitor before you market the property. This allows your solicitor to respond to buyer enquiries immediately rather than chasing you for documents mid-transaction.
5. Brief your estate agent
Your estate agent should be aware of the knotweed situation so they can answer questions from potential buyers accurately. An agent who is caught off-guard by knotweed questions, or who inadvertently misrepresents the position, can create additional problems. Open communication between you, your solicitor, and your agent keeps everyone aligned.
Sources and further reading
- Law Society — TA6 Property Information Form (4th edition, 2020), including Section 7.8 on Japanese knotweed: lawsociety.org.uk
- RICS — Japanese Knotweed and Residential Property (information paper), including the four-category risk assessment system: rics.org
- Property Care Association (PCA) — Invasive weed control accreditation scheme and approved contractor directory: property-care.org
- Misrepresentation Act 1967 — Provisions governing liability for false statements inducing a contract: legislation.gov.uk
- Wildlife and Countryside Act 1981 — Section 14(2) on the offence of planting or causing Japanese knotweed to grow in the wild: legislation.gov.uk
- Environment Agency — Managing Japanese knotweed on development sites: the knotweed code of practice: gov.uk
- GOV.UK — Prevent Japanese knotweed from spreading: gov.uk/guidance/prevent-japanese-knotweed-from-spreading
- UK Finance — Mortgage Lenders' Handbook, guidance on invasive species and property lending decisions: lendershandbook.ukfinance.org.uk
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Frequently asked questions
Do I have to disclose treated Japanese knotweed on the TA6?
Yes. Even if Japanese knotweed has been professionally treated and is no longer visible above ground, you must disclose the treatment history on the TA6 form. Section 7.8 asks whether the property is affected by Japanese knotweed, and a past infestation that has been treated still counts as an affirmative answer. You should provide the treatment plan, progress reports, and the insurance-backed guarantee to the buyer’s solicitor.
What happens if I do not disclose knotweed on the TA6 and the buyer finds out?
If you deliberately conceal known Japanese knotweed, the buyer can bring a misrepresentation claim against you after completion. Under the Misrepresentation Act 1967, the buyer may recover damages for the cost of treatment and any reduction in property value. In serious cases involving fraudulent concealment, the court can order rescission of the sale, effectively reversing the transaction. Buyers have six years from completion to bring a claim.
Do I need to disclose knotweed on a neighbouring property?
If you are aware that Japanese knotweed is growing on a neighbouring property, you should disclose this on the TA6 form. Section 7.8 asks about knotweed affecting the property, and an infestation on adjacent land — particularly within the seven-metre boundary zone recognised by RICS — is considered relevant. You are not expected to survey neighbouring land, but you must disclose what you know.
What does Section 7.8 of the TA6 actually ask?
Section 7.8 of the TA6 Property Information Form asks whether the property is affected by Japanese knotweed. The question covers knotweed on the property itself and knotweed on neighbouring land that the seller is aware of. You are expected to answer ‘Yes’, ‘No’, or ‘Not known’, and to provide additional details if the answer is yes, including treatment history and any insurance-backed guarantee.
Can I answer ‘Not known’ to the knotweed question?
You can answer ‘Not known’ if you genuinely have no knowledge of Japanese knotweed on or near the property. However, if you have seen knotweed, been told about it by a neighbour, or received a management plan from a previous owner, answering ‘Not known’ would be dishonest. Deliberate ignorance or wilful blindness does not protect you from a misrepresentation claim. If in doubt, explain what you know and what you do not.
Will disclosing knotweed stop the buyer getting a mortgage?
Not necessarily. Most mainstream mortgage lenders will consider lending on a property affected by Japanese knotweed if a professional treatment plan from a PCA-accredited contractor is in place and an insurance-backed guarantee has been issued. Untreated knotweed with no management plan is more likely to result in a mortgage decline. Disclosing early and providing the guarantee gives the buyer’s lender the best basis for approval.
What documents should I provide alongside my TA6 knotweed disclosure?
You should provide the specialist survey report identifying the infestation, the treatment plan prepared by the PCA-accredited contractor, progress reports from each treatment visit, the insurance-backed guarantee (typically covering a minimum of 10 years), any waste transfer notes if excavation was used, and photographs documenting the site before and during treatment. Presenting these documents proactively reduces follow-up enquiries.
Is Japanese knotweed the only invasive plant I need to disclose on the TA6?
Section 7.8 of the TA6 specifically asks about Japanese knotweed, making it the only invasive plant the form names directly. However, other invasive species such as giant hogweed, Himalayan balsam, or rhododendron ponticum may need to be disclosed under the broader environmental questions or as part of your general duty of disclosure. If you are aware of any invasive species on your property, it is safest to mention them.
Can I sell my property without treating knotweed if I disclose it?
You can legally sell a property with untreated Japanese knotweed as long as you disclose it honestly on the TA6. However, finding a buyer may be more difficult because most mortgage lenders will not approve lending without a treatment plan and insurance-backed guarantee. Cash buyers may proceed, but they are likely to negotiate a significant price reduction to reflect the cost of treatment and the impact on property value.
Does an environmental search always reveal Japanese knotweed?
Not always. Environmental searches check databases of known knotweed infestations, but these databases are not comprehensive. A property may have knotweed that has never been reported or recorded. Environmental searches are one source of information, but they do not replace a physical site inspection by a qualified surveyor. This is why the TA6 disclosure is so important — the seller’s honest answer may be the buyer’s primary source of information about knotweed.
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