The cold snap of last Winter may have delayed the growing season and the occurrence of insurance claims has even suggested that Japanese Knotweed is no greater risk to property than Buddleia, the butterfly bush, nevertheless, it continues to cause concern.

The facts are that the growing season is with us and many mortgage lenders are unlikely to lend on a property that has been affected by Japanese knotweed unless there is an insurance backed guarantee that the weed has been eliminated.

Remember, as part of the conveyancing process, owners are required to disclose any knowledge of its presence.

While it is not actually illegal to have Japanese knotweed in your garden, you could be fined up to £5,000 or be sent to prison for up to 2 years if you or your gardening contractor allow contaminated soil or plant material waste to spread into the wild.  An amendment to the Anti-social Behaviour, Crime and Policing Act 2014 requires you to prevent it becoming a problem in the neighbourhood too.

Now, with a recent court ruling, it seems you may be liable to pay damages for neighbours’ loss of enjoyment and amenity value if Japanese knotweed spreads to their property from yours but not, it seems, any claimed loss of property value.

If this were to happen, then the people responsible for managing the block, such as a property management company or the directors of a company set up to run block could, potentially and in certain situations, find themselves liable for any costs in respect of damaged caused, not just of flats in their own block but in neighbouring properties too.

The problem with Japanese knotweed is that it spreads rapidly. In winter the plant dies back to ground level but by early summer the bamboo-like stems emerge from rhizomes deep underground to shoot to over 2.1m (7ft) tall, and can suppress other plant growth.

Rhizomes can lay dormant for 20 years or more and eradication is a process likely to takes several years to complete. Japanese knotweed can grow up to 10cm per day, and because of its rapacious growth, it has been known to cause damage to building structures and substructures by targeting weak points, such as cracks in masonry, and attempting to grow through them. Here’s a sorry tale reported by London News Online.

Even if you take precautions, there is always a risk of this pernicious weed coming back and affecting property structure or values. You may want to check that your residents’ management company have liability insurance to cover any legal action taken against you.

Could you identify Japanese knotweed? And even if you could would you know what to do?  Check out the Government’s advice here


Reviewed 25 May 2022

The opinions and views expressed in the above articles are those of the author only and are for guidance purposes only. The authors disclaim any liability for reliance upon those opinions and would encourage readers to rely upon more than one source before making a decision based on the information.