As the Japanese knotweed growing season gathers pace, invasive plant specialist Environet has identified Somerset’s key knotweed hotspots for 2025. Recent data shows 583 verified Japanese knotweed sightings across the county, highlighting the widespread presence of this challenging plant.
The Japanese Knotweed Heatmap, now featuring over 100,000 verified sightings nationwide, is updated regularly throughout the year. It offers the most comprehensive online record of Japanese knotweed in the UK. Residents can enter their postcode to see local infestation levels, with risk areas colour-coded from yellow to red. This visual tool helps homeowners and prospective buyers understand their exposure to knotweed. The public can also contribute by reporting new infestations via the ‘Add Sighting’ feature, uploading photographs for expert verification.
Somerset’s Top 10 Japanese Knotweed Hotspots for 2025 reflect areas with concentrated knotweed growth, underscoring the importance of vigilance.
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Japanese knotweed was introduced to the UK in Victorian times via a shipment to Kew Gardens. Initially prized by gardeners, its invasive nature was soon realised. Today, it occurs in approximately 1.1 locations per square mile across England.
Emerging in early spring, knotweed quickly grows into dense stands featuring bright green, heart-shaped leaves and bamboo-like canes with pink flecks. The plant poses significant challenges for property owners due to its extensive underground rhizomes, which can reach depths of up to three metres and spread seven metres horizontally. Knotweed can penetrate cracks in concrete, driveways, pathways, drains, and cavity walls.
Although drastic property damage is uncommon, mortgage lenders require knotweed removal before property sales, creating potential delays and disputes. Infestations can reduce property values by around 5%. According to a 2023 DEFRA report, controlling knotweed costs the UK economy nearly £250 million annually.
Environet Director Emily Grant emphasised the value of early detection: “Mapping verified sightings helps local communities understand their risk and promotes timely treatment. Kikewise, vigilant monitoring is the best defence to prevent knotweed from establishing itself in gardens and neighbourhoods.
“At this stage of the year, knotweed is easily identified by its bright green, heart-shaped leaves growing in a zigzag pattern along the stems. Mature plants bloom in August with clusters of tiny white flowers, which are another identification clue.
“If you suspect knotweed on or near your property, send a photo to [email protected] for a free identification. If confirmed, a thorough survey will determine the infestation’s extent and recommend suitable treatments—whether excavation, herbicide application, or a combined approach.
“Community reporting is critical in combating this invasive species. By sharing sightings, homeowners can actively protect their properties and help curb the spread of Japanese knotweed.”