Japanese knotweed thriving in St Helens due to wet weather

The Star has previously reported how St Helens has been a particular hotspot for Japanese knotweed in recent years, which has been known to grow out of control and kill native plant species.

And following one of the wettest Februarys on record and higher-than-average temperatures, the weed has seen a further boom in reported sightings across the country.

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High numbers of knotweed reports

The species can kill native plants (Image: PA)
With the Japanese knotweed growing ahead of its usual season, invasive plant specialist Environet UK has revealed the knotweed hotspots on its online map.

Zoning into St Helens town centre, there are 499 reported knotweed occurrences within 4km of Bickerstaffe Street.

Moving to the south of the borough, the Environet site shows that there have been 407 reported knotweed occurrences within 4km of Warrington Road in Rainhill.

To the east of the borough, there have been 267 reported knotweed occurrences within 4km of High Street in Newton-le-Willows.

To the west of the borough, there have been 421 reported knotweed occurrences within 4km of Prescot Road in Eccleston.

To the north of the borough, there was a much lower figure of 86 reported knotweed occurrences within 4km of Church Road in Rainford.

What is Japanese knotweed?

The plant can grow to up to 8 feet tall (Image: Environet)
Japanese knotweed is native to East Asia and was introduced to the UK in the 1800s where it has since spread out of control. 

The plant is identified by "distinctive" red stems and bamboo-like appearance. It can grow up to 8ft tall and its roots can reach as wide as 28ft.

It can grow up to four inches a day and forms dense thickets which can kill native plant species, making it particularly harmful to the flora of the region.

If Japanese knotweed is found on private land, the landowner must take the necessary steps to prevent its further growth as tackling its spread costs the UK nearly £250 million a year.

Climate having 'detrimental impact on native species'

Tackling the spread can cost the UK £250m a year (Image: Environet)
According to Daniel Docking, the PCA’s Invasive Weed Control Group technical manager, the current climate conditions could have a detrimental impact on native plant species.

He said: “We can still expect late season frosts and dry weather in March and April, but Japanese knotweed has already started to establish itself and the resilience of the plant will mean it is in a strong position to thrive.

“At the moment many plants are doing well due to the weather conditions, including native species.

“But we’d still suspect the temperature to drop, meaning many plants will slow down their growth pattern.

“However, Japanese knotweed will be largely unaffected by these changes and that means it can start to dominate environments, with more opportunities to spread.”