What is Japanese Knotweed?

Toolbox Talk

22nd May 2019 | Info

Beware the pitfalls - potential fines of up to £5k and up to two years in prison

Japanese knotweed is a non-native invasive species that is thought to have been introduced into England in the early 19th century as an ornamental garden plant.


It is not a legal requirement to remove or treat Japanese knotweed, however, under schedule 9 of the Wildlife & Countryside Act 1981 you must not plant or cause to grow Japanese knotweed in the wild. You could also be prosecuted if you allow it to spread onto another person’s land. Transporting of the plant after removal comes under the Environmental Protection Act 1990 as it is a classified controlled waste.


It has large triangular shaped leaves that are 10-15cm in length, hollow green/red stems and small white delicate flower tufts in late summer to autumn. It can reach heights of 2m and often grows in dense thickets which prevent other native species from growing. It is these thickets that help yearly identification as the old stems that die off stay present until the following growing season.


It has an extensive range of habitats, including towns & gardens, woodlands, coastal & freshwater areas and wetlands.

Other Names for Japanese Knotweed

Japanese Rhubarb, Donkey Rhubarb, Monkey Weed and Elephant Ears.

Spread and reproduction

The spread of the plant is by vegetative means only. rhizomes underground or fragments of stems. It does not produce seed in the UK.

Treatment and disposal

Chemical treatment is the most effective way to control Japanese knotweed and it is important to understand the legislation and laws around chemical use and disposal before undertaking this form of control. It can also take up to three years to fully treat the area and for the rhizomes underground to be permanently killed.

Removal of the waste could result in up to a £5,000 fine or up to two years in prison if you allow plant material or contaminated soil to result in the transfer or spread into the wild. Burning is an option, however Japanese knotweed rhizomes and vegetation can remain active even after burning and so the area of burning must also be disposed of correctly. In both circumstances it is advisable to contact the Environment Agency to make sure you have the correct licences to undertake such operations.

Burying on site or at a designated landfill site with the correct certification can also be carried out if at a depth of 5m or 2m (if wrapped in a root barrier membrane layer). If burying on site, you must check with the Environment Agency that this is allowed and they must also be notified a week before any works commence.

When working near an infected area, there should be an exclusion zone from the edge of the area by 7m due to the underground spread of the rhizomes.

Further guidance on Japanese knotweed with useful links on information provided can be found at: https://www.gov.uk/guidance/prevent-japanese-knotweed-from-spreading

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