Property owners are being urged to watch for Japanese knotweed as spring 2026 approaches. The invasive plant begins to appear in spring and flowers during summer, but widespread confusion about its appearance means it often goes undetected until it becomes a serious problem.
Matthew Harwood, home insurance expert at Confused.com, said: "Japanese knotweed can be tricky to spot, and it's often mistaken for plants like Himalayan balsam or giant hogweed. Our research shows that only one in four UK homeowners or renters actually know what Japanese knotweed is, yet nearly one in five say they've been affected by it." He noted key signs include spade-shaped leaves with a pointed tip and rapid growth in warm weather.
Under UK law, you are not legally required to remove Japanese knotweed from your property, but you must prevent it from spreading to neighbouring properties or into the wild. Failure to control its spread can lead to prosecution, especially if it invades natural habitats. Soil or vegetation contaminated with knotweed may be classified as controlled waste.
Removal costs can reach up to £1,910 on average, according to Confused.com. Home insurance typically does not cover removal costs, but damage caused by the plant may be covered depending on your policy and whether you have taken steps to control it. Harwood stressed the importance of declaring knotweed when taking out insurance to avoid rejected claims.
Japanese knotweed is the most widespread of four invasive knotweed species in Britain, including dwarf, giant, and bohemian hybrids. It thrives in most soil types, particularly along roadsides, railways, riverbanks, and derelict land. The plant spreads through rhizome fragments as small as 1cm, making early detection and professional treatment crucial.
