Japanese knotweed is an invasive non-native species which, as it was brought to the United Kingdom as an ornamental garden plant in the mid-nineteenth century, is now established in the wild and considered to be an invasive plant.

It is actually an offence under section 14(2) of the Wildlife and Countryside Act 1981 to "plant or otherwise cause to grow in the wild" any plant listed in Schedule 9, Part II to the Act. This includes Japanese knotweed.
On the other hand, it is not considered an offence to simply have this invasive knotweed growing in your garden or on your land, and there is no legal requirement to control Japanese knotweed, unless doing so forms part of a legally binding contract or agreement with another party.

There is no need to report the presence of this very invasive weed on your land though, unless doing so forms part of a legally binding contract or agreement with another party.

This plant is not amongst the five species listed in the Weeds Act 1959. Those species actually are Common Ragwort, Spear Thistle, Creeping or Field Thistle, Broad leaved Dock and Curled Dock, but surprisingly not Japanese knotweed which can cause a lot of damage.

Any Japanese knotweed contaminated soil or Japanese knotweed plant material that you intend to dispose of is likely to be classified as Japanese knotweed 'controlled waste' under the Environmental Protection Act 1990. Untreated Japanese knotweed is not regarded as a Japanese knotweed 'hazardous waste' under the Hazardous Waste Regulations 2005 but material containing this invasive plant that has been treated with certain herbicides could be, or if the Japanese knotweed soil is contaminated with other contaminants.

The Control of Pesticides Regulations 1986 require any person who uses a pesticide to take all reasonable precautions to protect the health of human beings, creatures and plants, safeguard the environment and in particular avoid the pollution of water. Approval from the Environment Agency should be sought before application of pesticides in or near water.

Vigorous growth of this invasive plant can damage buildings and it also can damage hard surfaces as well as causing problems for native wildlife. Whilst it is therefore prudent to use Japanese knotweed control and dispose of Japanese knotweed, it should be done in such a way that does not contravene the above legislation regarding Japanese knotweed eradication and control. It is advised to contact a Japanese knotweed specialist that will provide you with Japanese knotweed solutions.