Hampshire Japanese Knotweed hotspots to be aware of

The species have their prime time for growing during the spring and summer, so Environet has analysed the latest data from its live online tracker to reveal the current hotspots.

The plant is responsible for damaging homes, pavements and drains and can spread up to seven metres horizontally, so is a problem you don't want to be dealing with on your property.

There are currently around 57,000 known occurrences at the time of writing, which can be seen on the interactive map here.

Where are the Japanese Knotweed hotspots in Hampshire?

The most prominent spot for Japanese Knotweed in Hampshire is Southampton, which has several high-infestation areas.

The eastern side of the Southampton area has the most at 67 occurrences within a 4km radius, the southern section has 64 and the western part has 58.

Southampton has the most recorded cases of Japanese Knotweed in Hampshire (Image: Environet) Portsmouth is the next worst after that with the northern side of the city having 44 occurrences in a 4km radius and the southern side having 41.

After that, there are 23 recorded occurrences in Winchester, 20 in the borough of Chandler's Ford and 18 near Havant. 

Both Portsmouth and Winchester had high case rates (Image: Environet) Smaller counts occur in places such as Petersfield (13), Bishop's Waltham (12) and Lymington (10).

How to spot Japanese Knotweed

Knotweed hibernates over winter but in March or April, it begins to grow, with red or purple spear-like shoots emerging from the ground which quickly grow into lush green shrubs with pink-flecked stems and bamboo-like canes.

The roots can grow as deep as three metres and spread up to seven metres horizontally. 

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What to do if you have Japanese Knotweed

The first step to tackling the plant is to commission a professional Japanese Knotweed survey and find out the extent of the infestation. They will be able to tell you where it originated, and the best way to tackle it.

Professional treatment should then be organised, which usually involves the use of herbicide for the excavation of the infestation.

If you’re buying a property and you want to be sure it’s clear of knotweed, particularly if it’s located in or near a hotspot, arrange a detection survey.