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Giant hogweed

Hogweed flowers

Giant hogweed

(Heracleum mantegazzianum)

Priority: -  Prevent

Tags: Terrestrial



Large upright plant up to 5 meters in height with hollow, ridged, green stems, some with reddish-purple spots

Leaves are dark green, toothed, and deeply cut into three large segments with stiff hairs on the undersides

Clustered white flowers in large umbrella-shaped heads up to 0.8 m in diameter


Biennial that reproduces by seed.

Habitat & Ecology

Prefers damp, rich soils. Found in riparian areas and along roadsides, ditches, and disturbed sites.


Very large plant with large flowers. Poses a health and safety risk as it contains toxic sap that can cause burns, blisters, and scarring of the skin. Increases erosion of streambanks.



Use protective clothing and eyewear when handling this plant. Cut off flowers to prevent seed production. Excavate pants, severing roots 8-12 cm below the soil surface. Do not compost; ispose of all plant parts in strong garbage bags. Immature plants can be controlled by covering with black plastic or by mowing at 2 week intervals; 3-5 years of follow-up treatment may be required.


Foliar applications with glyphosate are most effective in Spring followed by a Summer application on late appearing sprouts.


Watch the Attack of the Giant Hogweed:

Download WorkSafe BC's Toxic Plant Warning on Giant Hogweed here

Download the Invasive Species Council of BC's Giant Hogweed TIPS brochure here