26 infestations of Japanese knotweed across Slough have been discovered, thanks to a new tracking tool that launched this week

Exposed: The Japanese Knotweed Heatmap has found the infestations within a 4km radius of Slough, suggesting that homeowners should exercise vigilance, especially when buying or selling a property.

Introduced to the UK in the 1840s as an ornamental plant, Japanese knotweed now grows extensively along railways, in parks, waterways and gardens and is notoriously difficult to remove. The presence can prevent a mortgage lender from approving a loan and subsequently can impact decrease a properties value by up to 10%.

The plants usually grow from April or May, where red or purples asparagus shoots appear from the ground and grow rapidly, forming hard canes. The plant can grow around 10cm a day from May to July and can stand up to three metres tall.

Knotweed usually blooms in late summer, when it becomes covered in small white flowers. During the late autumn, the leaves fall, and canes turn brown and die, although they remain standing.

Nic Seal, Founder and MD of Environet, who created Exposed, said: “This heatmap will help us build a nationwide picture of the Japanese knotweed problem and give the general public the information they need to assess the risk in their local area.

“Berkshire is a Japanese knotweed hotspot, particularly around larger towns such as Reading, Bracknell and Slough. Exposed will be a useful tool for those buying and selling property in the county and local residents who want to be aware of infestations near their homes which could spread, putting their property at risk.”

If you’re worried about the plant emerging at your property, it is possible to purchase a specialist Japanese knotweed indemnity policy, which covers them for the cost of treatment, repairs, legal costs arising from third party claims and any diminution of the property’s value, should knotweed arise.