Bolton No 1 hotspot for Japanese knotweed

Knotweed emerges from winter hibernation in early spring with red or purple spear-like shoots emerging from the ground which rapidly grow into lush green shrubs with ink flecked stems and bamboo like cranes.

The roots can grow as deep as 3m and spread up to 7m horizontally, giving it a significant advantage over native plants.

It can cause damage to properties by blocking drains and pipes, destroying asphalt and resin surfaces and causing damp.

According to Environet, which has produced an interactive heatmap to highlight the issue, there are more than 55,000 recorded sightings of Japanese knotweed across the UK.

Japanese Knotweed hotspots shown on a heat map Hundreds of sightings of Japanese knotweed have been recorded across the Bolton Bolton has been revealed as the worst place with 684 infestations within a 4km radius.

The next nearest spot was Bristol which had 475, followed by St Helens, Merseyside with 441.

The place in Greater Manchester which came closest to Bolton was Ramsbottom where there are 176 infestations within a 4km radius.

The figures mean Bolton is more than four times as infested as surrounding areas.

A breakdown shows the infestation in the outer lying districts.

In  parts of Farnworth there were 412 incidents, in areas of Kearsley there were 368, in certain parts of Westhoughton there were 59, are in areas of Horwich there were 105, in areas of Little Lever there were 456, and in certain areas of Turton 151 and in  parts of Blackrod there were 52.

Japanese knotweed first came to the UK in 1850 but it was not known how problematic it is.

It came grow through cracks in concrete, tarmac driveways, pathways, trains and cavity walls.

Roots can grow three metres deep, spread seven metres wide and if it spreads between properties this must be dealt with before one is sold.

If Japanese knotweed is present in a home Asparagus like spears will emerge in early spring and then sprout pale reen leaves.

In May the plant will grow rapidly and steams will harden into bamboo-like structures and in summer they can grow at a rate of 10cms per day.

In August small clusters of creamy white flowers appear on the upper leaf axials.

Credit: Environet UK: Japanese Knotweed

Nic Seal, founder and Managing Director of Environet, said the aim was to raise awareenss.

He said: “Japanese knotweed tends to strike fear into the hearts of homeowners but as long as they’re aware of its presence and take action to remove it before it causes any serious damage or spreads to a neighbour’s property, there’s no reason to panic.

"By publishing the 2022 hotspots for Greater Manchester we hope to raise awareness and encourage people in the area to be vigilant for signs of knotweed as the growing season takes off, so they can act quickly if needed.

"Anyone living near or moving to one of these hotspots would be wise to check their garden carefully, enter their postcode into Exposed to find out how many known occurrences are nearby and if in doubt, seek expert help.”

To check the level of Japanese knotweed in your area visit https://www.environetuk.com/exposed-japanese-knotweed-heat-map