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Japanese Knotweed

Advice on identifying, controlling and disposing of Britain's most invasive plant.

Japanese Knotweed

Japanese Knotweed is a fast-growing plant that can grow through brickwork and concrete.

It grows up to 20cm a day and has a root system that can extend three metres in depth and seven metres in all directions.

It can cause serious structural damage if it grows into drains and building foundations. 

Japanese Knotweed is estimated to cost £165 million a year to control in the UK. The Council is keen for it not to spread across Fenland so has given advice on how to properly manage it.


Identifying Japanese Knotweed

Japanese Knotweed:

  • produces fleshy red tinged shoots when it first breaks through the ground
  • has large heart or spade-shaped green leaves
  • has leaves arranged in a zig-zag pattern along the stem. The stem is hollow, like bamboo
  • can form dense clumps that can be several metres deep
  • produces clusters of cream flowers in late summer
  • dies back between September and November, leaving brown stems.

Responsibility for controlling Japanese Knotweed

Responsibility for controlling Japanese Knotweed rests with the landowner or occupier of the land. They do not have to remove the plant from their land but could be prosecuted if they allow it to spread onto someone else's property. 

The Council takes appropriate action when Japanese Knotweed is found on the land and open spaces it manages.  This involves minimising the risk of it spreading and aiming to eradicate it in line with good practice. The Council's grounds maintenance contractor has also been trained in identifying the weed and treating it accordingly.

The Council can also consider efforts to control the weed when determining planning applications. If the Council becomes aware that it is present on a site, appropriate planning conditions may be imposed if permission is granted.

Getting rid of Japanese Knotweed

Please do not try to cut the weed down, mow or strim it. This will make it spread. 

Japanese Knotweed cannot be placed in your green binbrown bin or be taken to a recycling centre. It must be disposed of as 'controlled waste' because of how easily it spreads. 

Government Guidance explains how to control and dispose of Japanese Knotweed through chemical spraying and burning. Links are given to local controlled waste carriers who can dispose of the weed legally. 

Raising concerns about Japanese Knotweed

Please contact the Council if you think Japanese Knotweed is growing on its land or open spaces. The Council takes responsibility for managing its land seriously, but does not have the resources to assess knotweed on land that it is not responsible for. 

However, the Council can provide support if you are concerned that Japanese Knotweed on your neighbour's land may spread on to yours. Firstly, we recommend that you try to speak with your neighbour as they may not realise it is an issue.  You can also contact the Council for help to discuss the matter with those involved. The Council can help to decide which course of action is most appropriate in line with Environment Agency guidance.