Japanese Knotweed - Know Your Risk

Published on Feb 07, 2023 by Karen Yarnold on Conveyancing

Japanese Knotweed - Know your Risk

Japanese knotweed originated in eastern Asia. Its natural habitat is on the side of volcanoes, but it has spread into populated areas and has flourished on waste ground.

It was introduced to Britain by the Victorians as both an ornamental plant and cattle feed.

Unfortunately, Japanese knotweed has no natural enemies in Britain to keep it in check. No wildlife eats it, and no other plants can compete with its growth. This means the invasive weed has flourished to extreme proportions across the UK.

Would you be able to recognise Japanese Knotweed in your garden particularly as it changes its appearance with the seasons?


There have been several legal cases regarding this, and in the latest case reported the buyer found the weed whilst tidying up the garden next to his shed.  The Buyer subsequently sued the former owner, demanding he pay damages for misrepresenting whether there was knotweed at the property when he sold it.

The Seller had answered ‘no’ to the question on the TA6 property information form asking if the property had been affected by knotweed and argued that he ‘reasonably believed’ he was telling the truth when he did so.

He claimed he could not see the knotweed because of the large bush, which also probably stunted the weed’s growth before it shot up when the shrub was cut back after the Buyer moved in.

But it emerged in court that the knotweed may previously have stood at up to 2 metres tall, and there was also evidence it had been treated with herbicide in the past

The standard TA6 property information form asks whether a Seller’s property is affected by knotweed.

If it is affected, lenders may refuse to release funds or may first require a survey and specialist treatment. The specialist treatment can take many years to alleviate the problem, Therefore, an increasing number of property and lending transactions are being affected by potential knotweed problems. The average cost of a plan is approx. £5000

There are indemnity policies that can be taken out which will cover the property in the event of Japanese knotweed being found on the land. This cover can be taken out to provide protection for buyers and mortgage lenders if Japanese Knotweed is later discovered.  This will generally only be available if no knotweed has been discovered on your property or if it has been successfully treated in the past.

This insurance could cover the cost of a survey report to confirm the presence of knotweed, the cost of treatment, repair of any damage caused and could also extend to defending any legal proceedings in the event of any third party being affected