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Sellers keep quiet about Japanese knotweed

One in 10 (9%) people admit they would keep quiet when selling a property with knotweed, despite the legal risks, a YouGov poll commissioned by Environet has revealed.

This means that as 4,500 homebuyers could be duped into buying a home with the invasive plant.

There are approximately one million residential transactions that took place during 2023, with an estimated 5% of properties in the UK being affected by knotweed

Nic Seal, founder of Environet, said: “Discovering knotweed growing in the garden after you’ve bought a property is a very unpleasant and worrying situation to be in. If it can be proven that the plant was present at the time of sale, there is a very good chance of success in a legal case against the seller.

“Therefore, anyone who answers ‘No’ to the Japanese knotweed question on the TA6 form needs to be 100% certain that the property is not affected, which means no live rhizome under the ground of the property or abutting in the neighbouring land. That’s a difficult undertaking, so the general advice is to respond ‘Not known’.”

The risks of non-disclosure of knotweed are high, as demonstrated last year by a seller in Raynes Park, London, who was ordered to pay £200,000 in costs and damages to the buyer of their 3-bedroom family home after they failed to declare the presence of knotweed during the sale.

The seller claimed not to have known about the plant, which was located at the back of the rear garden behind the shed. Still, the judge decreed that the knotweed had been present for several years and would have been visible during summer, making the seller liable for the resulting diminution in the property’s value and legal costs.

The survey also showed that despite 77% of people claiming to be aware of Japanese knotweed, only 12% could correctly identify it from a gallery of six photographs of different plants, including bindweed and lilac. Buyers and sellers who are unsure whether a plant could be knotweed are advised to check carefully online for pictures showing its appearance at the specific time of year, to account for seasonal changes, or commission a professional survey.