Cutting and burning invasive weeds

Cutting down or digging up weeds and burning the waste plant material are useful, low-tech means of control.

Cutting Japanese knotweed will, over time, weaken the plant and help in its control. You must however take care in handling and disposing of cut plant material. Burning alone may not be sufficient to kill this plant. You should place burnt material on top of a membrane and monitor it for regrowth.

Cutting giant hogweed before the plants flower will help to prevent further seeds being deposited on the ground. This is an effective way of removing these species but it can take many years.

Pulling up Himalayan balsam before the plants flower is the most effective method of control. Cutting plants down before they flower can result in a more bushy plant that produces more flowers.

What you must do

Burning waste materials is a type of waste disposal. To burn waste in the open you may require:

• in England and Wales, an environmental permit or exemption
• in Northern Ireland and Scotland, a waste management licence or exemption.

In England and Wales, if you had a waste exemption registered before 6 April 2010 you may need to register a new exemption from environmental permitting or apply for an environmental permit. Check the Environment Agency's timetable for more information about when you will need to get your new exemption or permit.

Environment Agency: Timetable for when you need to apply for a new exemption or permit (Adobe PDF - 66KB)

You may qualify for an exemption to burn certain waste plant tissue and untreated wood if:

• you burn the waste at the place where it was produced
• you burn up to 10 tonnes in a 24 hour period.

The exemption references are:

• D7 exemption in England and Wales
• paragraph 30 exemption in Northern Ireland
• paragraph 30 exemption in Scotland.

If you have an exemption, you must comply with the exemption conditions.

You must register this exemption with your environmental regulator.

You must still ensure that your activity does not:

• endanger human health or cause pollution to water, air or soil
• constitute a risk to plants or animals 
• cause a nuisance in terms of noise and odour or smoke
• adversely affect the countryside or places of special interest.

Environment Agency: D7 burning waste in the open
NIEA: Paragraph 30 – Burning waste on land in the open
SEPA: Paragraph 30 – Burning plant tissue waste on land in the open

Notify your local council environmental health officer before you begin burning plant material.

Burning plant material should only give rise to white smoke.

Notify the local fire brigade before you begin burning and again when you finish. This will prevent them being called out unnecessarily.

You can leave cut stems to dry out in the sun rather than burning them.

Make sure you place cut Japanese knotweed material on a membrane and not in direct contact with the ground.

Giant hogweed sap remains toxic after the plant has been cut down. Make sure that you do not leave cut stems where they could injure people or livestock.