- Nearly 3 in 4 (76%) people can’t confidently identify Japanese Knotweed is
- More than 2 in 5 (44%) were unaware of the presence of the garden weed in their property ahead of their sale or rental agreement
- Over a quarter (28%) of those affected couldn’t claim on their insurance for the damage
- Home insurance expert at Confused.com shares tips on how to identify and treat the weed
Japanese Knotweed is plaguing homeowners and renters with staggering repair bills as the invasive weed hits peak season.
New research from home insurance experts at Confused.com reveals that homeowners and renters are paying an average of £2,929 to cover damage caused by the weed. According to the research, 92% of respondents have heard of Japanese Knotweed, and of this group, 10% live in an area considered affected by the invasive weed.
The research found that 24% of respondents who had experienced the weed found it in their garden, under the property, and inside the property - resulting in difficult damages to overcome. And for over a third (38%), it took over a year to treat or remove the weed.
Japanese Knotweed is an invasive and fast-growing weed that can cause extreme damages to properties and gardens alike. It is at its most prominent during the summer months through to October. The weed can grow up to 10cm a day, posing huge risks to homes and gardens.
That’s why half (50%) of buyers and renters would walk away from a property if the invasive weed was found. This rises to 84% who would demand a treatment plan first to ensure the weed is kept away.
Despite the fears around the damage the weed can cause, the research found that nearly 3 in 4 (76%) people can't confidently identify Japanese Knotweed, even though they've heard of it.And nearly a third (32%) of Brits are unsure if they live in an area that is considered at risk of Japanese Knotweed.
As a result, more than 2 in 5 (44%) were unaware of the presence of the garden weed in their property ahead of their sale or rental agreement.
The research found that Northern Ireland (22%), Wales (21%), and London (19%) are the areas in the UK with the biggest known risk of the weed.
The presence of Japanese Knotweed can cause major problems for homeowners - even when trying to sell their property. For over 4 in 10 (44%), the presence of Japanese Knotweed caused a delay in the sale or mortgage of their property. For a further 39%, the weed changed the decision on whether to sell altogether. While for over a third (37%), its presence caused a price reduction on the property.
Not only can the weed cause intense and sometimes irreversible damage to properties and gardens, but it can also have huge financial implications.
Japanese Knotweed has the potential to devalue properties or make it difficult to get a mortgage. Yet, 9% of property owners did not disclose that a property they sold or rented was affected by the weed.
According to the research, it’s a younger demographic who are less aware of what Japanese Knotweed is and the impact it can have. Of those aged 25 - 44, less than a quarter (22%) know exactly what Japanese Knotweed is. And with people in this age group generally being more active in the property market, they could risk being exposed to the adverse impact of the weed.
Japanese Knotweed can cause issues ranging from structural damage - pushing through tarmac, concrete, and building foundations - to property devaluation(1). Yet, over a quarter (28%) of those affected by the weed couldn't claim on their insurance for the damage. Yet, over a quarter (28%) who were affected by the weed couldn’t claim on their insurance for the damage.
Of those who were able to claim on their insurance for Japanese Knotweed damages, the research revealed the average amount successfully claimed was £4,117.
However, costs can soon creep up when the invasive weed is present. For professional removal, the average spend comes to £2,529. Whereas for a DIY removal, people affected are spending an average of £2,190 to remove the weed. And many people don’t realise that the removal of Japanese Knotweed is not covered by insurance, as it is considered a legal responsibility to prevent the invasive weed from spreading.
The most common ways Japanese Knotweed has been identified in and around homes is by a gardener (41%), self-diagnosed (32%), and by a neighbour or friend (26%).
Over half (55%) didn’t know that if Japanese Knotweed is present on a property, the property owner has a legal responsibility to control the plant and ensure it doesn’t spread to neighbouring properties. For 1 in 9 (11%) of those affected, Japanese Knotweed resulted in a dispute with a neighbour - with 3% that remain unresolved.
Japanese Knotweed can be difficult to find, especially if people don’t fully understand what it is and the risks it comes with. That’s why home insurance experts at Confused.com have developed a guide so homeowners and tenants know what to look out for during the summer months, when the weed is at its most active.
Matthew Harwood, home insurance expert at Confused.com comments:“As we approach the season for Japanese Knotweed, it’s important for homeowners and renters to understand the signs of the weed and the damage it can cause.
“Being similar to plants like Himalayan balsam or giant hogweed, it can be difficult for people to identify the weed. Recognising the plant's appearance and dominant times can help people to stay alert from July to October when the risk is at its highest. The easiest way to identify the plant is by its leaves, which are spade-shaped with a point at the end.
“If you find Japanese Knotweed on your property, it’s legally your responsibility to control it and prevent it from spreading to neighbours properties. Sourcing professional services to rid you of the plant is an effective course of action and will prevent it from spreading further.
“Home insurance doesn’t tend to cover the cost of removing Japanese Knotweed itself. Although, you may be covered for damage it causes, depending on your policy and whether you’ve taken steps to control it.
“Our Japanese Knotweed damage guide explains how to identify the weed, the risks, and the best ways to remove it.”
People have different experiences with Japanese Knotweed depending on its severity and the situation in which it is found. Two case studies from people who have experienced the effects of the invasive weed highlight the impact this could have on properties and gardens.
Case study: Sophie’s experience with Japanese KnotweedSophie initially had her offer to buy a house accepted in early August 2022, which should have been an exciting process. However, because of Japanese Knotweed, she was unable to exchange contracts and move in until 6 months later in February 2023, encountering a huge amount of stress in between.
The property Sophie purchased has a large garden, approximately 25m from the house to the back fence. The Knotweed was, and is continuing to, grow about 7m behind that fence.
The land behind the property is owned by a housing company who have held the deeds for about two decades and they have always been denied permission to build there, so it sits there unmaintained. Sophie tried several times to contact them and ask about the Knotweed, after being told she couldn’t do anything about it if it's not on her land, and they were refused contact.
After months of Sophie contacting every week, the mortgage and insurance companies yielded and allowed her to proceed. Sophie described the experience as “a total nightmare for months” and is “still always worrying about it because of the possibility of spreading and impacting resale a future resale”.
Sophie was being told she needed to have a treatment plan in place. Yet, she was unable to treat something that wasn’t on her land. She couldn’t do anything legally unless the housing company allowed it to spread onto her land, adding even more expense to the existing issue.
In 2019, Adam bought a house that had a Japanese Knotweed infestation at the bottom of the garden. The previous owners were aware of this and had started a treatment plan in 2018 that cleared a large area.
The previous owners had arranged for a 5-year treatment plan by a Knotweed specialist. They covered this with insurance in case the treatment plan needed to be extended.
To tackle the issue, the specialist came out twice a year, in spring and late summer, to check for new growth during peak seasons.
In 2022 there was some regrowth which was sprayed with weedkiller and the plan ended in 2023 with the 'all clear' certificate.
Although Adam experienced another occurrence in 2024, the specialists came out again free of charge. Luckily, there has not been any Knotweed since. Adam has branded the area in his garden as a no-dig zone to prevent disturbing any Rhizome.
At a later date when the fence needed replacing in that area the specialist advised that it was safe to dig as long as no soil left the area and all tools were washed there too. Now, it's been 2 years since Adam last saw any Japanese Knotweed in his garden.
-ENDS-
Unless otherwise stated, research carried out by One Poll on behalf of Confused.com of 2,000 UK homeowners and renters between 3rd and 10th July 2026.
Confused.com press office
About Confused.com
Launched in 2002, Confused.com was the UK’s first digital marketplace for car insurance and is one of the leading brands in the sector, generating over one million quotes per month. It has expanded its range of comparison products over the years to include home insurance, van insurance, motorcycle insurance, and car finance comparison, as well as a number of tools designed to save consumers money.
Confused.com is not an insurance company or lender. It provides an objective and unbiased service. By using cutting-edge technology, it has developed a series of intelligent web-based solutions that evaluate a number of risk factors to help customers with their decision-making, subsequently finding them great deals on a wide-range of insurance products, financial services, utilities and more. Confused.com’s service is based on the most up-to-date information provided by UK suppliers and industry regulators. Confused.com is authorised and regulated by the Financial Conduct Authority.
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