Japanese knotweed: what are your responsibilities?

Indicators of Japanese knotweed are as follows:

• Zig zag stems
• Lush green colour leaves
• Shield shaped leaves with a flat base
• Bamboo style stems
• Red tinged shoots
• Found in dense clumps
• In July it will sprout clusters of white flowers
• Between September and November it will leave brown stems once the leaves have died back

Other than hiring a specialist company to remove the knotweed for you, or using chemicals to kill the plant, you could choose to dig it out yourself.

Bear in mind however that the roots can grow to 3 metres below the ground, so regrowth is likely unless all the roots are removed. Once dug up you are also faced with the issue of disposal and the plant is classed as ‘controlled waste’ under the Environmental Protection Act 1990 and so can only be disposed of at licensed landfill sites. It should never be included in normal household waste or compost.

Despite the damaging impact the plant has on your property, it is not illegal for it to be present, and you are under no obligation to remove it or control it.  The presence of the plant can however have a serious impact on the sale potential of your property, and the price.  It can also deter insurance companies from providing you cover and potentially mortgage lenders could refuse to lend to you.

If you are selling your property and you are aware of Japanese knotweed within the grounds or the neighbouring property you are required to disclose that information when putting your property up for sale. The estate agents should ask as to whether there is a management plan in place and what these are in terms of the removal or future treatment of the plant.  If you are not honest and it is later discovered the buyers could claim for misrepresentation.  It is best to have this checked out before you put the property on the market for sale.

If you are looking to buy a property, even if the seller has stated that it is “not known” or a definitive “no” to Japanese knotweed being present, you should ask your own surveyor or a horticultural expert to confirm this.  It may also be in your interest to investigate with the seller that if the plant is not present in their own grounds, whether it is known to be a problem in the neighbourhood due to the prolific spreading of the plant.

If you are obtaining a mortgage to purchase the property your lender may not wish to lend on a property with Japanese knotweed.  Alternatively, they may lend if there is a treatment schedule in place and a Completion Certificate that confirms the weed has been remediated with a Guarantee in place for a minimum of 10 years.

While the presence of it may not be illegal, planting it yourselves or not taking reasonable steps to prevent it from spreading to the wild is a criminal offence and you could be served with a community protection notice under the Anti-Social Behaviour, Crime and Policing Act 2014.