AREAS in Cheshire have been pinpointed as a regional hotspots for the UK’s most invasive plant

Japanese knotweed has entered its spring growth phase and plant expert Environet has used data from its interactive online tracker to draw up a heatmap of its locations.

Exposed informs 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.

Chester and Northwich are both identified as hotspots on the map.

Cheshire Japanese knotweed infestations for 2021 include:

Location/Infestations within 4km radius

  • Northwich 47
  • Chester 45
  • Frodsham 18
  • Winsford 18
  • Helsby 10
  • Ellesmere Port 9
  • Whitchurch 8
Japanese Knotweed begins to grow strongly at this time of year

Japanese Knotweed begins to grow strongly at this time of year

But the figures in Cheshire are much lower than neighbouring Merseyside.

The Merseyside Japanese knotweed hotspots for 2021 are:

Location/Infestations within 4km radius

  • St Helens 440
  • Knowsley 291
  • Newton-le-Willows 242
  • Mossley Hill 215
  • Crosby, Sefton 130

Knotweed begins to grow in March or April, depending on the local ground temperature, reaching up to three metres in height by mid-summer.

Homeowners spending more time in their gardens this spring may notice purple or red asparagus-like shoots emerging from the ground.

Japanese Knotweed begins to grow strongly at this time of year

They grow into lush green shrubs with heart or shovel-shaped leaves and pink-flecked stems.

According to Environet, knotweed can push up through cracks in concrete, driveways, patios, paths, drains and even the cavity walls of our homes.

This can reduce a property’s value by 10 per cent and make it difficult to sell, unless a professional treatment plan is in place with an insurance-backed guarantee to satisfy mortgage lenders.

According to Environet’s research, approximately 5% of homes are currently affected, either directly or indirectly (neighbouring an affected property), knocking around £20 billion off UK house prices.

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.

Mat Day, Environet’s regional director for Merseyside, 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.”

Facts about Japanese Knotweed:

• Japanese knotweed arrived in the UK in the 1840s, in box number 34 of 40 Chinese and Japanese plant species delivered to Kew Gardens

• Knotweed grows at the incredible rate of around 10cm a day from May until July

• When it is fully grown it can stand up to 3 metres tall

• Approximately £166m is spent each year on treating the plant in the UK

• The Government estimates it would cost £1.5bn to clear the UK of knotweed

• Japanese knotweed can lie dormant but alive under the ground for up to 20 years

• Sniffer dogs are now helping in the fight against knotweed, detecting the unique scent of its rhizome beneath the ground

• 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 or to report a sighting, visit: