Giant Hogweed (Heracleum mantegazzianum)

Common names:
Give a thumbs up Giant Hogweed
Give a thumbs up Giant Cow Parsnip

General Plant Information (Edit)
Life cycle: Perennial
Sun Requirements: Full Sun
Full Sun to Partial Shade
Minimum cold hardiness: Zone 3 -40 °C (-40 °F) to -37.2 °C (-35)
Maximum recommended zone: Zone 9b
Plant Height: 6 - 12 feet
Plant Spread: 3 - 5 feet
Leaves: Unusual foliage color
Other: Handling plant may cause skin irritation or allergic reaction, do not touch the plant
Fruit: Showy
Flowers: Showy
Flower Color: White
Bloom Size: Under 1"
Flower Time: Late spring or early summer
Late summer or early fall
Uses: Cut Flower
Will Naturalize
Wildlife Attractant: Bees
Propagation: Seeds: Provide light
Stratify seeds: 6 weeks if you sow indoors
Suitable for wintersowing
Sow in situ
Start indoors
Can handle transplanting


Photo gallery:

Posted by Bonehead (Pacific NW - Zone 8b) on Mar 26, 2018 4:13 PM

Class A noxious weed in Washington state (relative new-comer, trying to eradicate before it settles in). Forms dense canopies that out-compete natives, and increases erosion along waterways. Dig out, but be cautious. As noted by others, the clear watery sap can sensitize the skin to sunlight, resulting in a blistering long-lived rash.

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Posted by funnynancy on Apr 28, 2014 7:43 AM

I recently saw a post on facebook that this plant is very dangerous. It claims the plant can be deadly and/or cause blindness. It showed men in protective suits removing the plant from gardens. Do you have any information about this?

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Discussion Threads about this plant
Thread Title Last Reply Replies
Interesting article on Giant Hogweed by crawgarden Nov 30, 2017 9:26 PM 2
Hogweed or cow parsnip by dukejohn2000 Jul 7, 2017 3:55 PM 2
Unidentified Ditch plant by Bubbeez Jun 15, 2017 11:08 AM 5
These "weeds" are turning into trees, and I'm going to let them! by eturner99 May 1, 2017 7:07 PM 17
Is that a weed or a native? by Bonehead Jun 24, 2013 12:52 PM 47
Wildflowers of Iceland and Greenland, Platanthera hyperborea by Ursula Aug 22, 2011 9:31 AM 18

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