Japanese knotweed—management
Produced in partnership with Phlorum and Groundsure
Japanese knotweed—management

The following Environment practice note Produced in partnership with Phlorum and Groundsure provides comprehensive and up to date legal information covering:

  • Japanese knotweed—management
  • The legal framework
  • Environment Agency code of practice withdrawn
  • Land remediation relief
  • Avoiding Japanese knotweed
  • Implications for sales, lettings and financing
  • What can landowners or purchasers do?
  • Enquiries before contract
  • Lease negotiations

Japanese knotweed was introduced to the UK in the 19th century as an ornamental garden plant. It had been used in Japan to stabilise sand banks and there have been suggestions that it was similarly employed to stabilise embankments in the UK.

Lacking the competitors, diseases and animals that keep it in check in its native range, knotweed’s uncontrolled and invasive nature quickly allowed it to become a pest in the UK. As only female plants were introduced, no pollen was available from male plants to allow fertile seeds to develop. Consequently, almost all knotweed in the UK has spread from small fragments of plant material (mainly roots) that have been transported to new locations in knotweed-contaminated soil.

Knotweed grows rapidly underground and pushes up annual shoots each spring. The roots and shoots are capable of exploiting gaps in buildings and hard surfaces such as concrete and tarmac, which can cause significant damage to them over time. The root system of knotweed can be very deep (a few metres) and spread several metres from the aboveground stems.

Not only can its presence delay development or land transactions, but those responsible for knotweed-affected land could face prosecution and potentially significant costs in resolving the situation. Remediation costs can run into hundreds of thousands of pounds for large infestations where excavation of the large root system is

Popular documents