Japanese Knotweed - Advice
Japanese Knotweed is an invasive non-native plant. It is a problem because:
· 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. You have a legal obligation not to cause it to spread if it grows on your land and must dispose of any waste carefully, complying with the law.
Correct disposal of plant material is vital to avoid the risk of spreading the problem further. Contact the Environment Agency for England and Wales (Tel: 08708 506 506) for advice on disposal because there are regulations which cover the composting, burning and burial of plant materials on-site and the transfer and disposal of material including ash to licensed or permitted landfill sites.
Failure to ensure safe, legal disposal or obtain an appropriate licence or exemption if required, could result in prosecution.
Householders should not put Japanese knotweed in your rubbish bin, or any green waste recycling schemes of any description, or your home compost bin.
If you are intending to treat or dispose of waste containing Japanese Knotweed, we recommend that you consult the Government’s website at:
The following points are general guidance based on the information provided by the Government:
· Householders can treat the plant yourself, but should take care when removing it, to ensure that it is not allowed to spread. Even the smallest piece of rhizome, stem or crown can potentially form a new plant.
· Composting Japanese Knotweed is generally not recommended unless great care is taken to keep the Japanese Knotweed separate from any other compost.
· You should not take Japanese Knotweed material to your local recycling centre. You should not remove Japanese Knotweed material from your property unless you have made a prior arrangement with a licensed landfill site for deep burial. Treatment on site is the preferred option.
· You may wish to employ a specialist contractor to remove the waste, but ensure that they have a waste carrier’s licence and record their details.
· You should not shred or strim the plant as this could cause rapid spread. Do not dig Japanese Knotweed as this is known to increase stem density and it encourages sprouting and spread.
· Hand pulling or cutting the plant can be used to control but will take several years for the rhizome to be exhausted and die. Any material which is removed can be left on a plastic sheet to dry and then burnt. This should be done on site to prevent the Japanese Knotweed from spreading. The cutting and pulling of stems encourages the plant to send up more shoots which can in turn be pulled.
· You can also use chemical herbicides. You should use a glyphosate based weed killer, but treatment will need to be ongoing and may take several years depending on how established the colony is. Such products can be bought from any good hardware store. Other products can only be used by professional authorised operators.