Do YOU live in a Japanese knotweed hotspot? Here's how to spot and get rid of it

Daily Mail​

20-07-2025

Bristol is the Japanese knotweed 'capital of England', new data from Environet shows.
In the year to date, there have been 1,440 reported sightings of Japanese knotweed in the South West city, according to the findings.
Merseyside is another hotspot for Japanese knotweed, with 2,963 sightings reported, but spanning a less dense area, at 11.87 episodes per square mile compared to 33.91 in Bristol.
Greater London is the third most prevalent Japanese knotweed hub, with 4,687 reported sightings and 7.74 incidents per square mile.
Lancashire came out in fourth place, seeing a hefty 8,612 sightings spanning 7.25 episodes per square mile.
Residents in Greater Manchester also need to be on high alert for Japanese knotweed, with the area seeing 3,558 Japanese knotweed reports, translating to 7.22 incidents per square mile.
Spanning further afield, the Isle of Man, a self-governing British crown dependency, also reached the top 10, as did the Channel Islands, Isle of Wight, Derbyshire and Nottingham, followed closely by the West Midlands and Surrey.
What is Japanese knotweed?
According to the Royal Horticultural Society, Japanese knotweed is a persistent, clump-forming herbaceous perennial, which was introduced to Britain as an ornamental garden plant but has since become an invasive weed subject to legal control measures.
Japanese knotweed first arrived in Britain in the Victorian times in a box of plant specimens delivered to Kew Gardens and was quickly adopted by gardeners and horticulturalists, who were unaware of its invasive nature.
Since then it has spread widely, with an average of 1.1 occurrences in every square mile of England and 3.9 in Wales, according to Environet.
Japanese knotweed can grow in most soil conditions found in Britain, particularly in man-made habitats, such as roadsides, waste ground, railway embankments and cuttings and spoil tips. It is also commonly found along rivers and streams.
Why is Japanese knotweed common in locations like Bristol?
Speaking to This is Money, Emily Grant, a director at Environet, said: 'It's likely that Japanese knotweed is most prolific near ports such as Bristol, Liverpool and Cardiff, because of historical shopping and trading practices.'
She added: 'In the nineteenth and twentieth centuries ships would return from all over the world carrying ballast, which often included soil containing non-native plant material like knotweed.
'That was then dumped to make way for the next cargo, and it quickly took hold. It may also have been planted deliberately to stabilise railway embankments and slag heaps.
'In industrial areas like Manchester, Lancashire and the Midlands, extensive soil movement from mining and construction accelerated its spread.'
How can I spot Japanese knotweed?
Japanese knotweed begins to emerge in early spring, quickly growing into lush green shrubs with pink-flecked stems, heart-shaped leaves and bamboo-like canes.
In August it starts flowering with bunches of tiny creamy-white blooms that hang in tassels.
It can pose serious problems for homeowners, with underground rhizomes that can grow up to three metres deep and spread up to seven metres horizontally, emerging through cracks in concrete, tarmac driveways, pathways, drains and cavity walls.
While serious damage to property is rare, mortgage lenders require knotweed to be dealt with when a property is sold, meaning it can cause legal disputes between neighbours and reduce a property's value.
Environet estimates that the presence of Japanese knotweed at a property can reduce its value by 5 per cent, though this is variable and will depend on the scale of the problem.
A 2023 Department for Environment, Food & Rural Affairs report put the cost of tackling knotweed to the economy at nearly £250million per year.
What should I do if I suspect Japanese knotweed?
The government's website states: 'You must stop Japanese knotweed on your land from spreading off your property.
'Soil or plant material contaminated with non-native and invasive plants like Japanese knotweed can cause ecological damage and may be classified as controlled waste.
'You do not legally have to remove Japanese knotweed from your land unless it's causing a nuisance, but you can be prosecuted for causing it to spread into the wild.'
If you do notice knotweed, you do not need to report it, but if it is on your property you should act sooner rather than later.
'The more it grows, the more it will cost to remove', Grant told This is Money.
You will not be able to sell your property until you have had any Japanese knotweed professionally dealt with, and you could be at risk of a legal claim from a neighbour if you leave it to spread.
Grant added: 'From there a treatment plan can be put in place, whether it's herbicide, removal, or a combination of both.
'Whatever option you go for, be sure to get an insurance-backed guarantee so if it starts to regrow you know you're covered – and that's what mortgage lenders will expect when you come to sell your property.'
Japanese knotweed must be carefully disposed of carefully. If you cannot dispose of it suitably on site, you must send it to a landfill site or incineration facility that has the correct type of permit.
It is best not to try and tackle a Japanese knotweed invasion yourself, unless you have appropriate training, skills and equipment.
How to find a new mortgage
Borrowers who need a mortgage because their current fixed rate deal is ending, or they are buying a home, should explore their options as soon as possible.
Buy-to-let landlords should also act as soon as they can.
Quick mortgage finder links with This is Money's partner L&C
> Mortgage rates calculator
> Find the right mortgage for you
What if I need to remortgage?
Borrowers should compare rates, speak to a mortgage broker and be prepared to act.
Homeowners can lock in to a new deal six to nine months in advance, often with no obligation to take it.
Most mortgage deals allow fees to be added to the loan and only be charged when it is taken out. This means borrowers can secure a rate without paying expensive arrangement fees.
Keep in mind that by doing this and not clearing the fee on completion, interest will be paid on the fee amount over the entire term of the loan, so this may not be the best option for everyone.
What if I am buying a home?
Those with home purchases agreed should also aim to secure rates as soon as possible, so they know exactly what their monthly payments will be.
Buyers should avoid overstretching and be aware that house prices may fall, as higher mortgage rates limit people's borrowing ability and buying power.
What about buy-to-let landlords
Buy-to-let landlords with interest-only mortgages will see a greater jump in monthly costs than homeowners on residential mortgages.
This makes remortgaging in plenty of time essential and our partner L&C can help with buy-to-let mortgages too.
How to compare mortgage costs
The best way to compare mortgage costs and find the right deal for you is to speak to a broker.
This is Money has a long-standing partnership with fee-free broker L&C, to provide you with fee-free expert mortgage advice.
Interested in seeing today's best mortgage rates? Use This is Money and L&Cs best mortgage rates calculator to show deals matching your home value, mortgage size, term and fixed rate needs.
If you're ready to find your next mortgage, why not use L&C's online Mortgage Finder. It will search 1,000's of deals from more than 90 different lenders to discover the best deal for you.
> Find your best mortgage deal with This is Money and L&C
Be aware that rates can change quickly, however, and so if you need a mortgage or want to compare rates, speak to L&C as soon as possible, so they can help you find the right mortgage for you.