Identifying Japanese knotweed

Japanese knotweed:

  • begins growing in early spring
  • can grow as much as 2cm per day
  • can reach a height of 1.5m by May and 3m by June
  • produces fleshy red tinged shoots when it first breaks through the ground
  • has large, oval green leaves
  • has a silver tinge on the underside of its leaves
  • has a hollow stem, similar to bamboo
  • forms dense clumps that can be several metres deep
  • produces clusters of cream flowers towards the end of August
  • dies back between September and November leaving dead, brown stems
  • will grow in any type of soil, no matter how poor
  • does not grow from seed.

Further information and photographs that will help you to identify Japanese knotweed and its roots (rhizomes) can be found in section 1.2 (page 10) of the Environment Agency code of practice.

In this guideline: