Giant Hogweed (Heracleum mantegazzianum) FAQs

Frequently asked questions about Giant Hogweed  for a UK resident:


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Giant Hogweed (Heracleum mantegazzianum)

A towering and imposing plant that has become a growing concern across the UK.  This striking botanical beauty has now become a serious threat to both human health and local ecosystems.

An example of Giant Hogweed with Common Hogweed in the foreground
Example of a Giant Hogweed leaf.

Everything about Giant Hogweed is very big. Giant hogweed has huge leaves often over 1.5 m long sometimes more than 2m and flower heads up to 80cm or more wide. Stems are green with purple blotches and coarse white hairs.

Along riverbanks, ditches, waste grounds and gardens, but also can be found along field margins and woodland clearings. It thrives on damp, nutrient-rich soils.

It blooms from June to July, with white flowers clustered in an umbrella-shaped head.

By seeds, which can spread by water or ground disturbance.

Giant Hogweed is a herbaceous biennial, which means it takes two years to reach maturity to flower and seed. Once Giant Hogweed reaches maturity it grows rapidly, reaching heights of 3-5 metres.

Yes, giant hogweed is toxic. Its clear sap causes photosensitivity in the skin which can produce severe burns.

It can cause severe skin and eye burns, blisters, long-lasting scars.

Yes, avoid going near it and do not touch the plant. Cover exposed skin and wear gloves if removing.

By breaking the lifecycle and preventing seed production. Repeated treatments maybe needed. Seek expert help for large infestations.

Yes, it is illegal to plant or cause giant hogweed to grow in the wild under the Invasive Alien Species (Enforcement and Permitting) Order (2019).

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