Giant Hogweed

Giant Hogweed

Giant Hogweed was introduced from the Caucasus to Victorian gardens in the 19th century. In the United Kingdom, Giant Hogweed has become extremely invasive in suitable habitats, such as river and stream banks, railway lines, disused waste land and other damp places.

Giant Hogweed is a tall, usually three to five metres, plant with several hundred small white flowers in large umbrella-like flower heads up to 500 millimetres across. Stems are green with dark-red or purple blotches and are hollow. Leaves are dark green and jagged in appearance and spiky are the ends.

Each flower head produces thousands of seeds, approximately 10 millimetres x 7 millimetres, that are easily dispersed by water, therefore the seeds can disperse rapidly along watercourses. The key identification features of the plant are:

  • often grows up to three to five metres in height
  • leaves expand up to 1.5 metres in width which have a jagged appearance with spiky ends
  • large flower heads that are usually 50 centimetres wide, it is important to note that in the first few years of a giant hogweeds growth the main flowering shoot may not appear
  • large seeds in clusters
  • purple blotched stems with a fine hair like appearance
  • hollow stems
  • spread by seeds

Harmful effects

The stems, edges and undersides of the leaves have small hairs containing phototoxic sap. The slightest contact with human skin can cause painful blistering and severe skin irritation when exposed to sunlight. Blistering can take 24 to 48 hours to appear after exposure. The reaction can recur for six years or more.

If you do come into contact with giant hogweed cover the affected area of skin immediately from sunlight. Then wash the skin with cold water as soon as possible. If contact is with the eyes or blisters occur seek medical advice.

Legal implications

  • It is not illegal to have Giant Hogweed on your land
  • You do not need to notify anyone about Giant Hogweed on your land
  • You are not obliged to remove or treat Giant Hogweed, but you must not plant or encourage the spread of Giant Hogweed outside of your property, this can include moving contaminated soil from one place to another or incorrectly handling and transporting contaminated material and plant cutting

What should you do

On your property, you should aim to control this plant and, to prevent it becoming a problem in your neighbourhood.

Control can be carried out by the homeowner, and does not require a specialist company. However due to the dangerous nature of the plant we do not recommend this, a specialist company will be skilled at control and can dispose of the plant waste safely.

Information on preventing the spread of invasive plants is available from GOV.UK

On no account should Giant Hogweed be included with normal household waste or put out in green waste collection schemes.

Where problems with Giant Hogweed occur in neighbouring gardens or land, we suggest that you speak or correspond directly with your neighbour or land owner who may already be taking action to control this weed.

Report Giant Hogweed

If you are concerned about Giant Hogweed on land in Salford let us know. Where it is on land owned by the council, we will include it in our treatment programme. If it is not on council land, we will endeavour to inform the relevant land owner.

Report it online

This page was last updated on 7 June 2016

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