Giant Hogweed - are you aware of the risks?

Giant hogweed.
Giant hogweed.
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By Joanne Dale, Countryside Management Delivery Branch, DARD

GIANT hogweed is a plant that may pose a risk to health because it produces a toxic sap which can cause blisters and permanent scarring in the presence of direct sunlight. The long hollow stems are attractive to children as ‘telescopes’ and ‘pea-shooters’ but they can cause serious blistering around the eyes, mouth and hands

Giant hogweed is a non-native species that was introduced as a garden plant from south-west Asia towards the end of the nineteenth century. It is now commonly found along river banks and roadsides. It is very invasive and can grow into large dense stands that shade out native vegetation reducing biodiversity. When it dies back in the winter it can leave bare ground susceptible to erosion by rainfall, flooded watercourses or trampling by livestock. Each plant can produce between 10,000 to 20,000 seeds which means the plant can easily spread. This can lead to giant hogweed invading amenity areas used for fishing, recreation and conservation resulting in risks to public safety.

Giant hogweed is easily recognisable by its huge size. It is unlikely to be confused with common hogweed which is smaller and found along roadside verges. It flowers from June to July and the hollow stem of the flowering plant grows up to an impressive 5m tall. The whole plant often dies soon after flowering and fruiting.

Farmers and landowners in receipt of Single Farm Payment must comply with Cross-Compliance rules which state that you must prevent infestation by invasive species, such as giant hogweed because they degrade the agricultural and environmental value of the land. If you have a NI Countryside Management Scheme (NICMS) agreement with a riparian zone option along a farm waterway, one of your management requirements is the removal of invasive species such as giant hogweed.

Farmers and landowners need to be very careful when dealing with this plant. Research has shown that spraying it with an appropriate herbicide early in the growing season is the most effective option. For more details please read the Giant Hogweed Best Practice Management Guide on the Invasive Species Ireland website, or the on-line publication on the DARD website at

For further information please contact Countryside Management staff at your local DARD office.