Giant Hogweed Identification

Giant hogweed, invasive plant
As with many plants and weeds, Giant Hogweed changes in appearance throughout the year. And though it is usually categorised as a biennial, some plants are perennial - producing only leaves the first year, followed by flowers the following year. 

Giant Hogweed seasonal image gallery

Here are some examples of how the plant looks during its growing cycle, as well as close-up shots of flowers, leaves and stems, to further assist you in the identification process.  

Giant hogweed flower head in summer

What do Giant Hogweed flowers look like?

Giant Hogweed flowers are Inflorescences (circular clusters of small, white flowers) that can measure up to 50 centimetres in diameter.

giant hogweed leaves, with jagged edges, similar to those of rhubarb

Identifying Giant Hogweed leaves

Leaves are large with serrated or jagged edges that can grow to up to 1.5 metres wide, and 3 metres long. Leaves have hairs or bristles on the underside, and are similar in appearance to the leaves of rhubarb.

the hollow, hairy green stems of giant hogweed with purple splotches, or specks.

The hollow stems of Giant Hogweed 

The green stems are hollow, thick and marked with purple specks and bristles or hairs.  They can grow up to 10 centimetres in diameter.

Invasive weed expert removing giant hogweed growth in summer

Giant Hogweed management & removal

You can see just how immense an infestation of Giant Hogweed can become in just one growing season.  Our Invasive weed expert completely protected from the dangerous sap as he works to remove the infestation.

Giant hogweed in seed, the plant can produce in excess of 10,000 seeds per plant.

Giant Hogweed in seed

The seed heads can produce in excess of 10,000 seeds per plant, so it's not surprising it is termed as an invasive species.

Giant hogweed seeds will be dispersed by the wind, and can lie dormant for up to 10 years.

Late summer seed heads of Giant Hogweed

As the plant dies back, seeds will drop to the ground or be dispersed by the wind. These seeds can lie dormant for up to 10 years.

What’s Next? Contact us today

Howard Downer


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.

Follow Dr. Knotweed to hear about the latest developments regarding Japanese knotweed and the implications of infestation.

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