Northwest NEWS

July 10, 2000

Home & Garden

Giant Hogweed

Giant Hogweed alert

   There are over 800 Giant Hogweed sites known in King County, according the the Department of Natural Resouces Public Health.

   "Coming into contact with the sap of Giant Hogweed, followed by exposure to sunlight, can produce painful, burning blisters, also known as photo-dermatitis," explains Jane Wentworth of the King County Noxious Weed Control Program. "The best thing people can do to avoid exposure is to be able to recognize it and learn how to control it."

   When removing the Giant Hogweed, great care needs to be taken to avoid contact with the plant's sap. Dig up the plant, including at least three inches of root, or spot spray it with an approved herbicide. Mowing or cutting the plants back does not prevent them from regrowing.

   Protect your skin and eyes from contact with the sap by wearing protective clothing and eyewear. Wash immediately with soap and water if skin comes in contact with the sap. Contact your health provider and tell him or her you suspect you have touched Giant Hogweed.

   Giant Hogweed sightings should be reported to King County Noxious Weed Control Program at 206-296-0290.

   Giant Hogweed is a member of the parsley family. It can reach a height of 10-15 feet when flowering. Flowering mid-May through July, the Giant Hogweed has white flowers clustered in an umbrella-shaped head that can be up to 2.5 feet in diameter across its flat top.

   Hogweed prefers moist soil, and can take over ravines and stream banks. It is a state-listed class A, and a Federally listed, noxious weed. Landowners are required to control noxious weeds on their property, according to state law RCW 17.10.

   Identifying photos can be found on the King County website at

   If you have questions or would like to request information, call the King County Noxious Weed Control Program at 206-296-0290.