Japanese Knotweed is a fast-growing, clump-forming, invasive perennial weed that can cause damage to structures and properties.

Why is knotweed such a problem?

As the warmer months approach, Japanese Knotweed growth dramatically increases, meaning it is important for sellers to fully understand the legal, financial, and practical significance and consequences of Japanese Knotweed.

There are many problems associated with Japanese knotweed, but we have highlighted two of the main concerns:


The treatment and management of Japanese knotweed is estimated to cost the UK economy millions of pounds every year.

With most treatment plans recommending the entire excavation and reinstatement of the affected area, individuals could be forced to pay over £10,000 for treatment and remediation of the affected land.

Rapid growth pattern

The rhizomes can grow to a depth of two metres and can extend horizontally up to seven metres. These roots allow knotweed to spread quickly and are part of the reason why it is so resilient to treatment.

Knotweed can re-emerge and re-grow at any time after lying dormant, especially if the ground is disturbed.

It is notoriously difficult to spot due to its unassuming appearance, and therefore, most homeowners are unaware that even gardening can cause disturbance and subsequent re-growth.

It can grow as much as twenty centimetres per day!

Legal issues when buying and selling property affected by knotweed

When selling a property, sellers are required to complete a Property Information Form, in which they must state whether the property is affected by Japanese Knotweed.

Increasingly, we are seeing claims brought by purchasers of property where sellers have answered ‘no’ to knotweed being present. But, when moving into the property, knotweed is then identified as being present.

Although not mandatory; there are helpful guidance notes produced by the Law Society to aid sellers to answer on the Property Information Form.

Within these notes, sellers are advised to only tick ‘no’ if they are absolutely certain that no rhizome is present in the ground of the property or within three metres of the property boundary, which would require a comprehensive specialist survey to be undertaken.

Even with a specialist survey, it would be extremely difficult for a seller to confidently say whether rhizomes are present under the ground.

They are not always visible above ground, and by ticking ‘no’ in the Property Information Form, sellers expose themselves to potential claims from purchasers for damages for the costs of removal of the knotweed and a possible reduction in the value of the property, as well as legal costs.

Last year, The Court of Appeal ruled in the case of Davies V Bridgend County Borough Council that a diminution in the value of a property caused by the encroachment of Japanese Knotweed from neighboring land is a recoverable loss and in certain cases, that loss could be a significant sum.

It is not a defence to any such claim that the seller was not aware of its presence. Therefore, it is better to state that its presence is “not known”, thereby putting the onus on the purchaser to make all reasonable enquires and investigations before the property is purchased.

Now more than ever, it is important that sellers are aware of the legal implications of their answers on the Property Information Form, especially in relation to Japanese Knotweed.

If you would like to discuss a potential claim with our expert litigation team, then please contact us on 0845 287 0939, complete our online contact form, or talk to us on the online chat below.