Revealed: Where Japanese knotweed has been spotted in Norfolk

Japanese knotweed was introduced from Japan in the 19th century, and can grow an inch a day

Norwich is the worst place for knotweed infestations in the county, according to new figures - Credit: PA

Norwich has the largest number of Japanese knotweed infestations in Norfolk, according to new figures.

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

Knotweed can cause severe damage to homes if left unchecked, with the potential to grow up through cracks in concrete, tarmac driveways, drains and cavity walls.

It is at its worst in the mid-summer and roots can grow as deep as three metres and spread up to seven metres horizontally.

Data compiled by Environet UK on its "Exposed" tracker has found Norwich tops the rankings for the most infestations in Norfolk, with 79 recorded within a 4km radius.

Swardeston, a village four miles south of Norwich, had the second-highest number of infestations at 63.

Fakenham followed with 15, Caister-on-Sea with 13, and King's Lynn with nine.

In 2021, Trowse was found to have the highest number of infestations with 79 reports.

A map showing Japanese Knotweed hotspots in the county

A map showing Japanese Knotweed hotspots in the county - Credit: Environet

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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.

"By publishing the 2022 hotspots for Norfolk 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."

A sign prohibiting entry to a site due to the presence of Japanese Knotweed

A sign prohibiting entry to a site due to the presence of Japanese Knotweed - Credit: PA

Japanese knotweed first arrived in the 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.

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.