The garden nightmare most home insurance won’t cover

Reviewed by: Helen Rolph
Home, Travel & Pet Insurance Expert

Written by: Stephen Gamble
Insurance PR Writer

Fact-checked by: Quotezone Editorial Team

This content follows our Editorial Guidelines

Last Updated: 22 May 2026
Read time: 4 min

Homeowners are being warned that their insurance won’t likely cover any damage caused by an invasive plant which grows rapidly during the spring and summer – Japanese Knotweed.

Home insurance experts from Quotezone.co.uk are urging homeowners to keep the plant under control if it is present in their gardens, or they could risk being sued or even prosecuted.

Japanese Knotweed is listed by the World Conservation Union as one of the world’s most invasive species, with a root system strong enough to damage concrete, roads and buildings.

Since most standard home insurance policies do not cover Japanese Knotweed,* homeowners who notice it on their properties should act immediately to prevent it from spreading and causing structural damage.

The average cost of removing and excavating Japanese Knotweed is around £6,500, but depending on the size of the infestation and the type of removal method, prices can range from £1000 all the way up to £20,000.**

Its roots are strong enough to grow beneath slabs and surfaces, causing them to lift or crack, and it can even grow through cracks in brickwork and retaining walls. If the invasive plant makes its way onto nearby properties, neighbours can also sue.***

Under the Wildlife and Countryside Act 1981, it is illegal to let Japanese Knotweed spread into the wild and those who do, could be imprisoned.***

Japanese Knotweed can be difficult to identify, but it will often have red or purple shoots in the spring. It also has creamy white flowers, hollow, bamboo-like stems and heart-shaped leaves.

To manage its growth, homeowners should spray or inject approved herbicides into the plant or call out a professional. It can take at least three years to treat, remaining dormant in the soil for many years – regrowing if disturbed or the soil is used elsewhere.****

Helen Rolph, home insurance expert at Quotezone.co.uk said: “Japanese Knotweed is a seriously invasive plant that can cause some real damage to homes and gardens, so it’s important people are aware of how to recognise it and what to do if it’s present on their property.

“Since standard home insurance won’t normally cover damage caused by the plant, it means homeowners have to deal with its removal on their own as well as paying for any damage it may have caused. This is why spotting the plant early and treating it as soon as possible is key.

“There are some examples where homeowners must legally declare Japanese Knotweed on their property. This includes when they’re selling the home and if their insurance provider specifically asks them about it directly.*****

“Homeowners should also be aware of the consequences that come with not containing the growth properly. If the plant grows into a neighbour’s garden, they could sue, and if it reaches the wild, homeowners could face prosecution. Some home insurance includes legal assistance, meaning there may be support for legal costs, so it’s important for property owners to check the details of their policy.

“There is a specialised product available, Japanese Knotweed indemnity insurance, that can be used to protect the property in case it becomes affected, however this doesn’t cover properties where the plant already exists. It’s best for homeowners to chat through the situation with the insurance provider if they’re worried, and review the options.”

As a price comparison site, Quotezone.co.uk helps over 4 million customers find savings on all sorts of essentials every year, such as home and landlord insurance. 

References:
*https://www.environetuk.com/japanese-knotweed/insurance
** https://www.checkatrade.com/blog/cost-guides/cost-removing-japanese-knotweed/
***https://www.pba-solutions.com/japanese-knotweed-news/japanese-knotweed-in-a-neighbours-garden/
****https://www.gov.uk/guidance/prevent-japanese-knotweed-from-spreading
*****https://japaneseknotweedexpert.co.uk/home-insurance-covers-japanese-knotweed/