Published in Escarpment Views, Autumn 2008:
     Giant Hogweed can grow taller than humans, and can be loaded with large white flowers. It may look like a beautiful ornamental specimen to add to your garden, but it’s a plant to avoid, not nurture. Don’t buy it or transplant it. Its watery, clear sap on bare skin can react with sunlight and cause burning, swelling and inflammation three days after exposure. Accoring to ontarioweeds.com, a new government Web site, the effects of contact with its sap can last for months and skin can remain sensitive to ultraviolet light for years. Getting sap in the eyes can cause blindness. If you get exposed to the sap of this plant, get medical help.
     Giant Hogweed is on the top 10 list of invading species by Credit Valley Conservation (CVC). It propagates only by seed, and it flowers only in its last year of existence, but its umbrella-shaped flowers contain many seeds. “Municipalities and conservation areas are spending thousands of dollars to get rid of it,” says Rod Krick, natural heritage ecologist with the CVC.
     If you have it growing on a rural property, it will be very hard to eradicate because cutting it down can expose you to its sap and scatter its seeds. Even when you think you’ve removed it, it can reappear from seven to 10 years later. It is also easily confused with the native plants Angelica, cow parsnip and waterhemlock. 
     “Don’t be a hero, just avoid it,” advises Mike Cowbrough, weed specialist in field crops with Ontario Ministry of Agriculture and Food. “If you think you have it, contact the ministry of agriculture or your municipality. Don’t burn it, compost it or send it to landfill. Leave well enough alone.”
     Cowbrough recommends getting familiar with the species first, but staying away from it in July and August when the flowers set seeds and definitely dressing in full protective gear, including goggles, if working to remove it at other times. “Respect it, leave it alone, and notify people of it.”