AN INTERACTIVE map revealing Hampshire’s hotspots for one of the UK's most invasive plants has been unveiled.

Following its winter hibernation, Japanese knotweed has entered its spring growth phase and experts have issued a warning to property owners as the intrustive plant an grow at the incredible rate of around 10cm a day.

Pushing up through cracks in concrete, driveways, patios, paths, drains and even the cavity walls of our homes, Japanese knotweed can reduce a property’s value by 10 per cent.

It can also make properties difficult to sell, unless a professional treatment plan is in place with an insurance-backed guarantee to satisfy mortgage lenders.

Hampshire Chronicle: Image: PA Image: PA

A new online tracker, created by Environet, reveals the latest hotspots in the UK, informing homeowners and potential homebuyers of the local presence of knotweed and the potential risk to their property.

Users can enter a postcode to discover the number of reported knotweed sightings nearby, with hotspots highlighted in yellow or red.

Data shows that Southampton is the worst affected area in Hampshire, with 35 infestations within a four-kilometre radius.

Portsmouth is the second worst affected area, with 31 infestations.

Winchester takes third place with 15 infestations, Andover is next with 11 infestations and Basingstoke close behind with nine.

Hampshire Chronicle: Image: PAImage: PA

According to Environet’s research, approximately 5 per cent of homes are currently affected, either directly or indirectly through a neighboring affected property, knocking around £20 billion off UK house prices.

Homeowners spending more time in their gardens this spring may notice purple or red asparagus-like shoots now emerging from the ground and quickly growing into lush green shrubs with heart or shovel-shaped leaves and pink-flecked stems.

The general public can help in the fight against knotweed by reporting suspicious plants using the heatmap’s ‘Add Sighting’ feature and attaching a photo to be verified by experts.

Hampshire Chronicle: Image: PAImage: PA

Luke Walton, Environet’s Regional Director for Hampshire, said: “Knowledge is power when it comes to Japanese knotweed and this heatmap is invaluable to homeowners and buyers who want to assess the risk in their local area. With the stamp duty holiday extended and lockdown restrictions beginning to ease, the property market is busier than ever – but failing to carry out the appropriate checks for knotweed can turn out to be an expensive mistake.

“Despite its fearsome reputation, with professional help, the plant can be dealt with and the value of a property largely restored. I’d urge anyone buying or selling a property, or homeowners wishing to preserve the value of their home, to be vigilant for signs of spring growth and check Exposed to see whether they live in a high-risk area.”

Property owners who fail to stop the spread of knotweed on their land can face fines and even a jail sentence under ASBO legislation

To view Japanese knotweed infestations in your area or to report a sighting click here.