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A picture of a Giant Hogweed

Giant Hogweed

Heracleum mantegazzianum

Also known as

Cartwheel Flower, Giant Cow Parsnip, Hogsbane

Heracleum mantegazzianum - Berce du Caucase 1 by Marie-Claire (CC BY-SA 3.0)

Full Sun
Easy care
Moderate watering
Frost Hardy

H7

RHS hardiness

-20°C

Minimum temperature

Expected size

Height
Spread

3m

Max

2m

2m

Min

1.5m

4 years to reach maturity

Flowering

  • spring
  • summer
  • autumn
  • winter

This plant has a mild fragrance

More images of Giant Hogweed

Heracleum mantegazzianum 05 by Line1
Rbk dolde
Heracleum mantegazzianum (Meise) JPG1a
A photo of Giant Hogweed

Giant Hogweed Overview

Heracleum mantegazzianum is the species commonly known as giant hogweed, it typically grows over 2m in height. This poisonous, giant, perennial has large divided leaves and thick, hairy, ribbed stems covered with reddish-purple markings. Green-white flowers appear in late summer, these are arranged on structures called umbels. These are clusters which radiate from a central stem point, producing flowers on stalks of roughly equal length, to form a flattened or slightly rounded, horizontal surface of blooms. It is now an offence to plant or encourage certain species in this genus such as giant hogweed to grow in the wild in the UK. Easily confused with the related species Heracleum sphondylium, commonly called hogweed, these plants grow to notably different sizes, but are tricky to distinguish. Plant size is the best identifier, this species grows much larger compared to hogweed. The leaf shape also differs slightly between these species. For this plant, giant hogweed, the leaves are more textured, pointed and in a three-dimensional arrangement and in hogweed, the leaves are generally arranged in a flat, single plane.

Common problems with Giant Hogweed

How to harvest Giant Hogweed

Generally not hrvested

Other uses of Giant Hogweed

Can be grown as an architectural plant in flower borders but remove (wearing appropriate safety clothing) all spent flower heads before they set seed.