FAQs About Japanese Knotweed - TP Knotweed


Japanese knotweed (Fallopia japonica) is a herbaceous perennial plant of the family Polygonaceae. Native to Japan, China and Korea, the plant was originally imported into the UK by Victorian horticulturists, who valued it for its aesthetic appeal.

Removed from its harsher native habitat and natural predators, the plant thrived in UK soil following its first escapes into the wild in the nineteen century. It quickly spread to most parts of the UK, leading to its listing in the Wildlife and Countryside Act 1981 as a pest species. Outside of the UK, it enjoys a reputation by the World Conservation Union as the world’s worst invasive species.

The plant has gone by a number of English names over the years, including fleeceflower, Himalayan fleece vine, monkeyweed, monkey fungus, Hancock’s curse, elephant ears, pea shooters, donkey rhubarb, sally rhubarb, Japanese bamboo, American bamboo, and Mexican bamboo.

Closely related species include giant knotweed (Fallopia sachalinensis, syn. Polygonum sachalinense) and Russian vine (Fallopia baldschuanica, syn. Polygonum aubertii, Polygonum baldschuanicum).


Lenders will handle cases of Japanese knotweed differently according to their particular guidelines. Every lender is different; their guidelines outline each lender’s policy towards Japanese knotweed, its impacts and at what point it becomes an issue for property owners. Here is the stance of some of the biggest mortgage lenders:


Barclays demands an expert site assessment, and will not offer a mortgage until the knotweed has been treated.


Nationwide Building Society says: “If knotweed is prominent less than seven metres from the house we request a specialist report about eradication before deciding whether we can lend. Even if further away we require written confirmation from the borrower they are happy to proceed with a mortgage application despite presence of the plant.”


Santander expects professional knotweed treatment before lending homeowners money. It also expects you to keep money aside for future treatments in order to keep the garden clear.


Japanese knotweed represents a real threat to homes and other buildings. Emerging shoots can break apart brick and mortar, damaging structural integrity and reducing aesthetic appeal. Underground, root systems can grow up to three metres deep and seven metres wide, damaging water, gas pipes and structural foundations. In severe cases, walls, foundations and utility supplies risk being destabilised by the spreading plant.

Huge sums are being spent in the UK controlling the weed. In 2004, a DEFRA review of non-native species policy stated that a conservative estimate for the costs involved in eradication would be £1.56bn.


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