Top five worst areas in Cambridgeshire for Japanese knotweed

In Cambridgeshire, 220 verified sightings of the invasive plant have been recorded, according to new data from Environet.

The worst-affected areas in the county include St Neots, Peterborough, Wisbech, March and Cambridge.

Emily Grant, director at Environet, said: "Japanese knotweed is now firmly established right across the country, which means homeowners everywhere should know what to look for.

Japanese knotweed is the UK's most invasive plant and poses a "significant" threat to properties. (Image: Getty Images)

"My advice to anyone living, or buying a home, in a Japanese knotweed hotspot is to check your garden regularly during the growing season.

"At this time of year, an established knotweed plant can be identified quite easily by its hard bamboo-like canes and distinctive bright green shield-shaped leaves, which grow in a zig-zag pattern along the stem.

"The earlier it’s spotted, the easier and cheaper it is to deal with.

"Acting quickly with professional advice will prevent it spreading further and help protect both your property and its value."

Japanese Knotweed can cause serious damage to homes and gardens if left uncontrolled (Image: Getty Images)

Japanese knotweed is notorious for its rapid growth and ability to cause structural damage, devalue homes, and create legal disputes if it spreads across property boundaries.

The plant spreads through its underground rhizomes, which can extend up to seven metres laterally.

It was introduced to the UK in the Victorian era as an ornamental plant, but quickly became widespread due to contaminated soil movement and infrastructure development.

The economic cost of Japanese knotweed across the UK is estimated at £246.5 million per year, making it the second most costly invasive non-native species after ash dieback.

Are there cases of Japanese Knotweed near you? (Image: Newsquest)

Environet’s online tracker, Exposed: The Japanese Knotweed Heatmap, is based on Environet’s own enquiries, public sources and verified sightings submitted by members of the public.

Cambridge tops the county rankings, with 40 verified sightings, followed by Peterborough with 37, Wisbech with 13, March with 10, and St Neots with eight.

Research by Environet and Censuswide, conducted in January 2026, suggests that seven per cent of UK homes – more than 1.58 million properties – are affected by knotweed, reducing average property values by around five per cent or £13,500.

The company offers free identification services for suspected cases via email, and, if confirmed, arranges site surveys to determine the extent of the infestation and recommend treatment options.

Japanese Knotweed can cause damage to your garden and your property, so it is important to know when it flowers, what it looks like and how to remove it (Image: Getty Images/iStockphoto)

During summer, Japanese knotweed is most easily identified by its tall, upright canes – which can grow two to three metres high – and dense clusters of stems emerging from a central crown.

The plant’s shield-shaped leaves grow alternately along the stem, and by late summer, cone-shaped tassels of creamy-white flowers appear on the upper canopy.

Early detection and intervention are crucial for effective management and can help protect neighbouring properties as well as preserve property values.

Homeowners are encouraged to remain vigilant, especially in high-risk areas, and to seek expert advice if they spot the tell-tale signs of this invasive and persistent plant.