Environmental guidance for your business in Northern Ireland & Scotland

Burying invasive plant material on site

Burying invasive plant material on site

Taking plant material and soil containing plant material away for disposal off site uses valuable landfill capacity and increases the likelihood of the spread of invasive plants. Another option is to bury this soil and plant material on your own land because, without sunlight, plants cannot survive and seeds will not germinate.

However, this material will need to remain buried for several years to ensure that it will not grow again. Giant hogweed seeds can be viable for up to 15 years and Japanese knotweed rhizome (underground root-like stems) is believed to survive for 20 years.

What you must do

Soil and plant material containing Japanese knotweed may need to be buried 5 metres below ground level. You should place a barrier membrane on top of the material and fill the hole with clean soil. In some situations, alternative methods which do not require such deep burial are available.


Soil containing Himalayan balsam and giant hogweed seeds should be buried at least 1 metre below ground level.

You must not bury anything other than plant material and soil containing invasive plants that have originated on site.

You must make sure that deep burial does not interfere with the ground water level.

Buried soil and plant material that have been treated with a herbicide that does not break down in the environment could cause groundwater pollution. If you intend to bury treated material, you should treat it with glyphosate herbicide only. Check with the NIEA or SEPA.

Herbicides that do not break down in the environment are described as persistent. Those that do break down are described as biodegradable or non-persistent. The herbicide packaging or safety data sheet will state whether it is persistent or non-persistent.

Soil contaminated with some persistent herbicides will be classed as hazardous and so will need to be disposed of as special waste.

Hazardous/special waste

You must follow the guidelines for spraying plants with herbicide and digging up plants.

See the pages in this guideline: Spraying invasive plants with herbicide and Dgging up invasive plants.

Good practice

You should bury the material in an area where it is not likely to be disturbed. You should keep records of the quantity of material that you have buried and a map showing the location of the burial pit and its depth. Use signs to mark the burial pit and keep heavy tracked machinery off the area.

You should not bury materials deeply within 7 metres of an adjacent landowner's site.

Further information

Invasive Species Ireland: Terrestrial plants

Invasive species in Ireland report (PDF, 1.04MB)

Scottish Government: Non-native species information

Scottish Natural Heritage (SNH): Non-native species

Back to Giant Hogweed, Japanese Knotweed and other invasive species home page

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