Ipswich tops rankings for Suffolk's knotweed infestations again

Japanese Knotweed in full flow

Ipswich has the highest number of knotweed infestations, according to new data - Credit: Archant

Ipswich has by far the largest number of Japanese knotweed infestations in Suffolk again, latest data has revealed.

The figures come as the invasive plant returns from a winter hibernation – posing risks to property owners by knocking as much as a tenth off the value of homes.

The plant can grow up to three metres in height by mid-summer, pushing up through concrete, driveways, drains and the walls of houses.

A map of knotweed infestations across Suffolk

A map of knotweed infestations across Suffolk - Credit: Environet UK

Data compiled by company Environet UK on its "Exposed" tracker has found Ipswich tops the rankings for the most infestations in the county, with 47 recorded within a 4km radius.

In comparison, the next highest, Beccles, had 29 recorded infestations.

Lowestoft ranked third-highest with 26 infestations, while Stowmarket had 21 and Halesworth had 12.

Ipswich also topped the ranking in the 2021 figures released by Environet.

Nic Seal, founder and managing director of Environet, 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.

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"By publishing the 2022 hotspots for Suffolk 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.”

Japanese knotweed first arrived in UK in 1850 in a box of plant specimens delivered to Kew Gardens.

Favoured for its rapid growth and pretty heart-shaped leaves, it was quickly adopted by gardeners and horticulturalists who were oblivious to its invasive nature.

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.

For homeowners, the plant can pose serious problems if left unchecked, with the potential to grow up through cracks in concrete, tarmac driveways, pathways, drains and cavity walls.

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

While serious damage to property is rare thanks to regulation which requires knotweed to be dealt with when a property is sold to a buyer using a mortgage or if it encroaches across a garden boundary, it commonly impacts use of the garden, causes legal disputes between neighbours and can impact a property’s value by around 5%.

People who spot an infestation, characterised by the plant's purple or red asparagus-like shoots, can mark it on Environet UK's online map, with each picture verified by experts.