Giant hogweed mapped: How to identify and track deadly plant growing in the UK

Giant hogweed mapped: How to identify and track deadly plant growing in the UK


Giant hogweed, also known by its Latin name Heracleum Mantegazzianum, was first found in southern Russia and Georgia. The plant is part of the Apiaceae family, which includes popular herbs like parsley and coriander. Giant hogweed can reach over 10ft in height, and according to the Royal Horticultural Society (RHS), “most gardeners will want to eradicate it, as it is potentially invasive and the sap can cause severe skin burns”. 

How to identify and track giant hogweed

Hogweed is especially dangerous because the plant’s sap contains a chemical named furocoumarin, which makes human skin sensitive to sunshine and can cause terrible blistering.

The blistering can even recur over the span of several months and years.

The Woodland Trust has outlined how giant hogweed looks so that you can identify the dangerous plant.

Stems – the stems are green with purple blotches and have stiff, white hairs. The stems are hollow with ridges and a thick circle of hair at the base of each leaf stalk.


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Leaves – the leaves are huge, and can measure up to 1.5m wide and 3m long, and are often divided into smaller leaflets. The Woodland Trust says they are alike to rhubarb leaves, with jagged edges and the underside of the leaf being hairy.

Flowers – the flowers of the giant hogweed appear in June and July, and are small and white. They appear in clusters on “umbrella-like heads” that face upwards.

Seeds – the seeds are dry, flat and oval. They are almost 1cm long and tan coloured with brown lines.

You can see the difference between giant hogweed and normal hogweed from the leaves.

Regular hogweed leaves are more round, in contrast with the jagged edges of the giant hogweed leaves.


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The plant can also be confused with cow parsley, but the crucial difference is that cow parsley only grows to three to four feet, unlike giant hogweed which can grow to a towering 12 feet.

The plant is found throughout Britain, and usually by river banks where seeds can be transported by the water.

The RHS also says that areas most affected by giant hogweed include “gardens and allotments adjacent to infected woodland, heathland or common land”.

You can view the exact location of giant hogweed reports in the country by using the Plant Tracker. 

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How do I get rid of giant hogweed?

There is no legal obligation for landowners to dispose of growing giant hogweed, but it is illegal to plant or grow certain species of invasive and non-invasive plants in Britain – including giant hogweed.

The Government website states: “You must not import, transport, keep, breed, sell, use or exchange, grow or cultivate, or release into the environment certain invasive alien species.

“If you do so, you can be fined or sent to prison for a maximum of up to two years.”

To dispose of giant hogweed, you must:

  • Use a registered waste carrier
  • Send it to an authorised or suitable disposal site – check with the site directly, contact your local authority or check the Environmental Agency public register
  • Your local authority or council can help arrange the disposal of giant hogweed.

When dealing with giant hogweed, the RHS says: “When controlling giant hogweed, always wear gloves, cover your arms and legs, and ideally wear a face mask when working on or near it.

“Cut plant debris, contaminated clothing and tools are potentially hazardous too.”

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