The seller has a neighbour’s herbicide letter. Is that a management plan for this plot?

What is the fuller explanation?

Herbicide programmes are site-specific. A contractor writing to next door may name a year, a chemical approach and a boundary. None of that treats your side, your shed base, or a crown growing through this lawn. RICS knotweed guidance is concerned with the property being reported on. A neighbouring letter can be evidence that knotweed exists in the area. It is not a remediation contract you can enforce, and it may not even say the treatment worked. Government guidance on not causing spread still applies if any part of the plant is on the plot you will occupy. The letter does not suspend that.

Ask the surveyor whether they saw knotweed on this plot, on the neighbour’s plot, or neither, and whether the letter was in the papers they were shown. Then ask the solicitor what the letter actually promises and to whom. Do not file it as your management plan in a lender’s questionnaire. If this garden has no plan of its own, the honest answer is that the only paper is about next door. If you need this plot assessed, instruct a remediation firm for this plot. Do not assume the neighbour’s contractor will come round because a copy was left on the hall table.

What should you ask your surveyor?

• Did you see knotweed on this plot, or only a letter about next door?
• Does the letter say it covers this side of the boundary? If it does not, please do not imply that it does.
• Are you giving a management category based on the letter? Please do not.

What are the typical next steps?

1. Send the lender the survey and, separately, the letter, labelled as the neighbour’s.
2. Ask the solicitor who the letter binds.
3. If this garden needs a plan, it needs its own plan.

Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.

Also asked about this

Which pages should you read next?

• The survey did not lift a decking board. Why might a winter crown still be a limit rather than a clear garden?
• A root barrier is visible at the fence. Can the survey say it is continuous?
• What does mygov.scot tell you to do about a Home Report repair marked as needing future attention, not only one marked urgent?
• Guide: What should you do if a survey mentions Japanese knotweed?
• All UK home survey questions

Sources

• RICS: New Japanese knotweed standard comes into effect (Property Journal, 21 March 2022)
• RICS: Japanese knotweed and residential property, RICS professional standard, 1st edition, effective 23 March 2022
• GOV.UK: How to stop Japanese knotweed from spreading (updated 12 February 2026)