With the Japanese knotweed growing season now well underway, the Isle of Wight’s knotweed hotspots for 2025 have been confirmed – with Shanklin named the worst area for the invasive species.
There are a total of 554 verified knotweed sightings on the Isle of Wight, according to Environet’s online Japanese Knotweed Heatmap. In the national Japanese knotweed hotspots list, the Island is the 8th worst-affected county in England.
Now populated with over 100,000 known incidences of the UK’s most invasive plant, the map is updated with new verified sightings throughout the year, providing the most comprehensive online record of Japanese knotweed in the country.
Members of the public can enter their postcode to discover the number of sightings nearby, with hotspots highlighted in yellow, orange or in the worst cases red, helping them understand the level of risk posed to their home or one they wish to buy.
They can also help populate the heatmap by reporting knotweed infestations using the ‘Add Sighting’ feature and attaching a photograph of the plant so it can be verified by experts.
The Isle of Wight’s Top 10 Japanese knotweed hotspots for 2025 are:
| Rank | Location
|
Total
incidences |
| 1 | Shanklin | 79 |
| 2 | Newport | 78 |
| 3 | Ventnor | 66 |
| 4 | Bembridge | 49 |
| 5 | Ryde | 36 |
| 6 | Sandown | 31 |
| 7 | Cowes | 30 |
| 8 | Freshwater | 29 |
| 9 | East Cowes | 25 |
| 10 | Brading | 11 |
Japanese knotweed first arrived in UK in the Victorian times in a box of plant specimens delivered to Kew Gardens and was quickly adopted by gardeners and horticulturalists, who were unaware of its invasive nature. Since then, it has spread widely, with an average of 1.1 occurrences in every square mile of England.
Knotweed begins to emerge in early spring, quickly growing into lush green shrubs with pink-flecked stems, heart-shaped leaves and bamboo-like canes. It can pose serious problems for homeowners, with underground rhizomes that can grow up to 3m deep and spread up to 7m horizontally, emerging through cracks in concrete, tarmac driveways, pathways, drains and cavity walls.
While serious damage to property is rare, since mortgage lenders require knotweed to be dealt with when a property is sold, it can cause legal disputes between neighbours and reduce a property’s value by approximately 5%. A 2023 DEFRA report put the cost of tackling knotweed to the UK economy at nearly £250 million a year.
