Giant Hogweed Danger for Eastern Ontario – EOHU Health Warning – Cornwall – July 16, 2010

Cornwall ON – Giant Hogweed, a toxic plant that can burn and cause permanent blindness, is raising concern all over the country. Recent confirmed findings within the Five Eastern Counties have the Eastern Ontario Health Unit (EOHU) warning residents to be on the lookout.
Originally from Asia, Giant Hogweed can grow 15 to 20 feet (4.5 to 6 metres) in height. Its leaves are nearly 5 feet (1.5 metres) wide and feature hairs on their underside. The plant’s hollow stem has dark reddish-purple splotches and coarse white hair. Incredibly, one plant can have thousands of seeds.  To view photos of the Giant Hogweed, visit the homepage of the EOHU’s website at
Giant Hogweed’s danger lies in its clear and watery sap. If the sap from a broken stem or crushed leaf, root, flower or seed comes into contact with skin, it can cause severe burns, blistering and painful sores when the skin is exposed to sunlight. Plus, contact with the eyes can lead to temporary or permanent blindness.
“All residents should be cautious. But I would like outdoor workers, including road maintenance crews cutting roadside ditches, lawn and garden workers, as well as outdoor recreationalists to be extra careful,”
explains Dr. Paul Roumeliotis, Medical Officer of Health.
If you come in contact with Giant Hogweed, wash affected areas immediately and keep the affected area out of the sun and seek medical advice. To remove hogweed from your property, you must take special precautions:
  • Wear protective clothing, including gloves, long sleeves, pants, and eye protection, rain coat and boots.
  • Avoid getting sap on your skin.
  • Immediately remove any flower heads to prevent seed growth and dispersal.
  • Sever the plant roots 8 – 12 cm below the soil surface.
  • Dispose of all plant parts in double-bagged garbage bag, seal the bag and DO NOT COMPOST or put it in your yard waste.
  • Return to plant site periodically to remove any new plant growth.
  • Wash the clothes you wore to remove the plant afterwards (avoid contact with soiled clothing or tools).
If you see Giant Hogweed in a public area, the Eastern Ontario Health Unit asks that you please inform your municipality.


  1. Our property came with a giant hogweed. Whe we determined it was taxic, I took the recommended precautions to cut the leaves and the flower head and stalk. I did not dig up the root (as it can be huge, but poured about 2-3 ounces of gasoline into the opening of the flower stalk. That was 10 years ago, the weed has not grown back

  2. The hogweed didnt come back but he blew the neighbors pool to hell

  3. We live in downtown Toronto. 2 weeks ago, I pulled a hogweed from our back yard. I did not know at the time what it was and fortunately, it came out easy without plant breakage and I did not get a burn. We will keep looking now for re-growth. We live in a condo site and our plot of flower space was the only one affected.

  4. send the hog weed to b.c. for the m.p.’s to eat…!

  5. Just got back from a holiday at a cottage in a relatively wooded area of Quebec, across from Renfrew Co.
    While there, I developed painful oozing blisters. When I returned I went to the E.R. to have these lesions identified and treated, was sent to another hospital, had bloodwork, swabs and a biopsy of one of the lesions. NOBODY had an answer. I don’t remember coming in contact with anything resembling Giant Hogweed….Ideas?

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