Japanese knotweed is the most common of 4 invasive knotweed plant species in the UK.

These are:

• Japanese knotweed
• Dwarf knotweed
• Giant knotweed
• Bohemian (hybrid) knotweed

How to identify Japanese knotweed

See a description and photographs of Japanese knotweed on the Non-native Species Secretariat website.

Where knotweed grows

Knotweed can grow in most soil conditions found in the UK, particularly in man-made habitats, such as:

• roadsides
• waste ground
• railway embankments and cuttings
• spoil tips that are made up of waste material from mining or quarrying

It’s also commonly found along rivers and streams.

How knotweed spreads

Knotweed spreads through:

• direct rhizome (root) growth
• new plant growth from the parent plant’s stem and rhizome fragments – a new plant can grow from pieces of rhizome as small as 1cm

If you have knotweed on your land or property

You must stop Japanese knotweed on your land from spreading off your property. Soil or plant material contaminated with non-native and invasive plants like Japanese knotweed can cause ecological damage and may be classified as controlled waste.

You do not legally have to remove Japanese knotweed from your land unless it’s causing a nuisance, but you can be prosecuted for causing it to spread into the wild.

How to stop knotweed spreading

Do not treat knotweed yourself unless you have the appropriate skills and experience. You can find companies that specialise in treating knotweed.

Spray with chemicals

Spraying or injecting the stems with chemicals can be an effective treatment to stop knotweeds spreading. You must only use approved herbicides.

You’ll have to respray. It usually takes at least 3 years to treat Japanese knotweed. Knotweed rhizome can remain dormant in the soil for many years and will regrow if disturbed or if the soil is relocated.

When using chemicals, you may need to:

• make sure anyone spraying holds a certificate of competence for herbicide use or works under direct supervision of a certificate holder
• carry out a Control of Substances Hazardous to Health assessment
• get permission from Natural England if the area is protected, for example sites of special scientific interest
• get permissionagreement from the Environment Agency if the plants are near water – you can apply online for this herbicide agreement in England, or you can apply using the PDF form

To dispose of certain chemicals, you may need:

• an environmental permit
• a waste exemption
• trade effluent consent

You must dispose of chemicals through a registered waste carrier to a permitted waste disposal facility.

Find out how to treat and dispose of invasive non-native plants (RPS 178).

Bury it

You must notify the Environment Agency at least one month before you bury the knotweed.

You can dispose of the dead brown canes of Japanese knotweed by composting on site, as long as they’rethey are cut (not pulled) a minimum of 10cm above the crown.

You must bury knotweed material:

• on the site it came from, including ash and soils containing potential knotweed propagules
• at a depth of at least 5 metres, if you have not sealed with a material called a geotextile membrane
• at a depth of at least 2 metres, if you have sealed with a geotextile membrane

You must make sure that any geotextile membranes used for burial are:

• undamaged
• large enough to minimise the need for seals
• sealed securely
• will remain intact for 50 years
• ultraviolet (UV) resistant

You can use a contractor with experience burying knotweed. Check that they’re part of an assurance scheme, such as one with a relevant trade body.

Burn it

If you’re a business that wants to burn Japanese knotweed, you must:

• tell the Environment Agency at least a week before you burn it
• tell the environmental health officer at your local council
• get a burning waste in the open exemption (a D7 exemption)
• follow local byelaws and not cause a nuisance

If you’re an individual who wants to burn Japanese knotweed, you only need to check with your local council that burning is allowed.

Knotweed crowns and rhizomes may survive burning, so you must follow the guidance for how to bury it or how to dispose of it off site.

Companies that specialise in treating knotweed

You can supervise the management and disposal of knotweed yourself, or you can hire a specialist to do it for you.

Look for a contractor with the following accreditations and registrations:

• Amenity Forum Membership
• BASIS Professional Register
• BASIS Amenity Training Register
• BASIS Nominated Storekeeper (NSK) Professional Register

Many of these companies belong to one of these trade bodies:

• Invasive Non-Native Specialists Association (INNSA)
• Property Care Association (PCA)

How to dispose of Japanese knotweed off site

If you cannot dispose of Japanese knotweed suitably on site, you must send it to a landfill site or incineration facility that has the correct type of permit.

To find out where you can send it, contact the Environment Agency or your local waste disposal site. You must tell the Environment Agency that you have done this and where you have sent it.

You must use a registered waste carrier and an authorised landfill site or suitable disposal site.

You must follow the law if you have been employed to transfer goods or material by road and you’re disposing of any waste that has or might have Japanese knotweed in it.

You must not:

• dispose of Japanese knotweed with other surplus soil
• sell soil contaminated with Japanese knotweed as topsoil

You can only reuse soils contaminated with knotweed after treatment on the site where they were growing.

You cannot get a waste licensing exemption for the use of Japanese knotweed.

Before you transfer Japanese knotweed waste, you must:

• check with the waste site in advance to make sure it’s got a permit to accept material containing invasive plants – the waste site may also need time to prepare
• tell the waste site that you’re transferring Japanese knotweed waste
• operate within the conditions in treatment and disposal of invasive non-native plants: RPS 178
• get an environmental permit to transport and dispose of controlled waste

When you transfer the Japanese knotweed waste, you must cover or enclose it in the vehicle so that no waste can escape during your journey.

After you transfer Japanese knotweed waste

After you have transferred the Japanese knotweed waste at the disposal site, you must:

• brush vehicles down vigorously or jet-wash them to clear them of any Japanese knotweed
• inspect your vehicles to check there are no trapped pieces of plant or rhizome

Contact the Environment Agency

You can contact the Environment Agency for help if you:

• have more questions about how to handle waste containing Japanese knotweed
• want to find out more about when you need a licence to dispose of Japanese knotweed
• want to complain about waste producers who are not telling people they employ how to transfer Japanese knotweed – this is breaking the rules on their waste duty of care