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Jazmin Perry

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Japanese knotweed has a reputation for being the most aggressive, destructive and invasive plant in the UK, and many people would be put off of purchasing a property if they discovered that the weed affected it.  Japanese knotweed spreads quickly – it can grow up to 10cm a day with the roots extending up to three metres deep and seven metres across, it can cause significant damage to buildings, devalues properties, and costs a fortune to eliminate, so it can be a nightmare for homeowners.  The recent case of Downing v Henderson though, highlights how Japanese knotweed can still come back to haunt you, even after an affected property has been sold.  


Here, Jonathan Downing purchased a £700,000 house in London from Jeremy Henderson.  After moving in, Mr Downing discovered Japanese knotweed growing behind a bush next to a shed in the garden.  Mr Downing subsequently brought proceedings against Mr Henderson for misrepresenting whether there was knotweed at the property when he sold it.


The background

Due to the hardship that Japanese knotweed can cause, the Property Information form (a standard form completed by a seller in a sale process) requires a seller to answer ‘is the property affected by Japanese knotweed?.  The available answers are ‘yes’, ‘no’ or ‘not known’.  In this case, Mr Henderson answered ‘no’, which Mr Downing claimed was a positive assertion that there was no knotweed at the property, and that this was therefore a misrepresentation.  Mr Henderson argued that he reasonably believed he was telling the truth when he filled in the form and that he couldn’t see the knotweed due to the bush.  Expert evidence though suggested that the weed had previously stood up to 2 metres tall, and there was evidence that it had been treated with herbicide. 


The decision

The Judge found that Mr Henderson did not genuinely believe that the property was unaffected by knotweed at the time it was sold, and his defence was dismissed.  Mr Henderson was ordered to pay £32,000 in damages to Mr Downing (in respect of the cost of investigating and excavating the plant, and the diminution in value of the property caused by the presence of Japanese knotweed) plus Mr Downing’s legal costs of up to £95,000, and of course, Mr Henderson was responsible for his own legal costs, too.  


The points to take away…

If a property is or has been affected by Japanese knotweed, the seller should declare this on the Property Information form.  If a seller is unsure whether or not the property is or has been affected by Japanese knotweed, then they should tick ‘not known’.  A seller should only answer ‘no’ to whether the property is affected by Japanese knotweed if they are certain that there is no Japanese knotweed on the property (or, cautiously, in the vicinity of the property considering how quickly the weed can grow and spread). 

Sellers should also note that if any of their replies to enquiries change during sale process, then they need to inform their solicitor so that the buyer can be updated.  If a seller becomes aware that an original reply to enquiry has become outdated before exchange of contracts and fails to inform the buyer, then the seller may find themselves liable for misrepresentation.

Buyers should always have a survey carried out (that includes the garden, and, where possible, gardens of adjoining properties) prior to exchange of contracts.  This applies to buyers of houses and flats or apartments, as the cost of remedial works could result in a significant increase in service charge payments for those liable to pay them.

For buyers purchasing new builds, note that developers and builders are not obliged to complete the Property Information form, and so the solicitor acting should raise specific enquiries in relation to Japanese knotweed, to understand whether it affects or affected the property.


Recently, some of the standard forms used in property transactions have been amended by the Law Society of England and Wales.  The forms that have been amended are the Leasehold Property Enquiries form (LPE1), Leasehold Information form (TA7), and Completion Information and Undertakings form (TA13).  For more information on the amendments and what they mean for you, see here.

Consistent with our policy when giving comment and advice on a non-specific basis, we cannot assume legal responsibility for the accuracy of any particular statement. In the case of specific problems we recommend that professional advice be sought.

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If you have any questions relating to this article or have any legal disputes you would like to discuss, please contact the Dispute Resolution team on

[email protected]
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