Japanese knotweed

Japanese knotweed is Britain’s most invasive non-native plant. It was originally brought from the Far East as an ornamental plant by the Victorians but it has now widely naturalized and occurs across the UK as well as Europe, USA, Canada and New Zealand.

There are four main reasons why Japanese knotweed is a problem in Devon and elsewhere:

  • it spreads easily via rhizomes and cut stems or crowns
  • it out-competes native flora
  • it is difficult and expensive to control or eradicate
  • it can cause structural damage to buildings.

Because of its regenerative properties and invasive habit Japanese Knotweed is listed under the Wildlife and Countryside Act 1981 as a plant that is not to be planted or otherwise introduced into the wild. The Environmental Protection Act 1990 also lists it as ‘controlled waste’ to be disposed of properly. You have a legal obligation not to cause it to spread if it occurs on your land.

More information about how to identify, control and dispose of Japanese knotweed can be found at GOV.UK – Prevent Japanese knotweed from spreading.

Japanese knotweed in Devon

Japanese knotweed occurs in most parts of the County. It is mainly found in gardens, on road verges, river banks, railway embankments and waste ground.

Without surveying and recording the distribution of Japanese knotweed there is no way of knowing where it occurs, whether it is increasing and the typical habitats it colonises. Knowing the full extent of the problem of Japanese knotweed colonisation in the County will help the Devon Knotweed Forum identify priorities for control and management. It is therefore important to report any sightings of the plant in the County to the Devon Biodiversity Records Centre.

Devon Knotweed Forum

The Devon Knotweed Forum is an alliance of organisations in Devon with an active interest in the co-ordinated control of Japanese knotweed, its hybrids and other invasive knotweeds in Devon.

For more information and guidance please read the Japanese knotweed information booklet (link) produced by the Devon And Cornwall Knotweed Forums.

Aims and objectives

The aim of the Forum is to raise awareness of the problems caused by Japanese knotweed, share information about control and increase recording.

The objectives of the Forum are:

  • to assess the true scale of the problem, the costs and implications of Japanese knotweed infestations in Devon and to disseminate this information widely
  • to identify centres of best practice for the control of Japanese knotweed
  • to develop, evaluate and disseminate information about innovative and successful approaches to the management of Japanese knotweed
  • to prevent the further spread of Japanese knotweed through education, legislation and good practice
  • to encourage the eradication of Japanese knotweed and its hybrids through co-ordinated control
  • to work in partnership with the Cornwall Knotweed Forum and other groups and organizations.

Organisations involved

The Knotweed Forum is made up of over 40 organisations including local authorities, countryside and conservation groups, utility and transport operators and developers. The Forum is currently chaired by representatives from Devon County Council and the Environment Agency. If you want to join the Forum please email nature@devon.gov.uk.

Contractors for knotweed control

The following document details knotweed contractors and consultants operating in Devon. They offer specialist knotweed control services; however, other weed control contractors can be located through trade or business directories.

Reputable contractors should be Amenity Assured, BACCS registered and have warranty backed insurance. The Amenity Assured scheme involves three totally independent and separate audits being carried out annually on each contractor, including an unannounced on-site assessment, a full audit of a contractor’s premises, records and certification and an end-of-season check with clients to ensure treatments have been successfully completed. Contractors should be contacted before employment to ensure that they meet these criteria.


This list has been made available by the Council for information purposes only. The Council makes no representation, endorsement or warranty of any kind as to the standard or competence of any person listed above, or the accuracy of the information provided. Any arrangement for works to be carried out with any person or company listed will be an agreement between you and that person. In no event shall the Council be liable for any loss or damage, including indirect consequential loss or damage, arising out of any use of the list or any goods, works or services provided by any person on this list.