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Giant Hogweed

Image of Giant Hogweed

What is Giant Hogweed?

Giant Hogweed (Heracleum Mantegazzianum) is an invasive and highly toxic plant that has severe safety issues when in close contact with humans and animals. It was introduced as an ornamental plant by the Victorians.

Its appearance is similar to cow parsley but on an enormous scale, growing up to 6 metres in height. Foliage creates a dense canopy over surrounding land, smothering native flora and seriously affecting biodiversity. Giant Hogweed thrives beside watercourses, causing erosion of riverbanks.

Why is Giant Hogweed a problem in the UK and Ireland?

The watery sap of the plant contains harmful toxins that cause photo-dermatitis and can cause blindness. After exposure to sunlight, painful blistering occurs where the sap has come into contact with skin. The effects may not become apparent for up to 48 hours after contact with the sap/stem.

Prior to coming into contact with Giant Hogweed:

  • Always wear non-porous gauntlet gloves when examining the plant
  • Wear long-sleeved, long-legged garments
  • Use goggles, particularly when undertaking clearance work
  • Remember that even the dead stems can give a nasty burn

Should you come into contact with Giant Hogweed:

  • Immediately wash the area of skin thoroughly with water
  • Protect the area from exposure to direct sunlight by covering with clothing, bandaging etc.
  • Seek medical advice


Think you could have Giant Hogweed on your land? Click here to identify Giant Hogweed.


Giant Hogweed and the Law

Wildlife and Countryside Act (1981)

Giant Hogweed is listed under Schedule 9 of the Wildlife and Countryside Act (1981) and is classified as an invasive species

Schedule 9, section 14 states that it is an offence to plant or otherwise cause the species to grow in the wild.

Section 14(2) states that “if any person plants or otherwise causes to grow in the wild any plant which is included in Part 2 of Schedule 9, he shall be guilty of an offence”

An offence under the Wildlife and Countryside Act (1981) can result in a criminal prosecution.

Environmental Protection Act (1990)

Giant Hogweed must be disposed of safely at a licensed landfill site according to the Environmental Protection Act (Duty of Care) Regulations, due to its invasive and toxic nature.

Section 33 of the EPA states that it is an offence to deposit, treat, keep or dispose of controlled waste without a license.

An infringement of the Environmental Protection Act can result in an unlimited fine.

Anti-Social Behaviour, Crime and Policing Act (2014)

Individuals and organisations failing to control Giant Hogweed on their land can be issued with a notice under antisocial behaviour orders (ASBOs).

Penalties can range from an on-the-spot fine of £100, to prosecution and a fine of up to £2,500 for individuals and £20,000 for organisations.

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Japanese knotweed rhizome


TCM provide science based solutions to a wide range of industries including construction, rail, road and the London Overground.

Howard Downer, MD of TCM Ltd


Howard Downer, AKA Dr. Knotweed, has over 20 years of experience as an Environmental Consultant and is regarded by his peers as one of the most knowledgeable people in the Japanese knotweed industry.

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