Volunteer finds hundreds of giant hogweed plants in Kitchener

·4 min read

KITCHENER — Volunteers from the Giant Hogweed Mitigation Project say they found a lot of giant hogweed in Kitchener area last summer and are already starting to see them this spring.

Fred Kuipers says that throughout May and June last year, he found an estimated 400 to 500 plants over 20 to 30 sites.

Giant Hogweed is a notorious plant that grows extremely quickly to be up to 15 feet tall with poisonous sap that causes severe burns when it reacts with UV light.

Kuipers, a software engineer, says he would go for walks along the Grand River close to where he lives to get some fresh air during the pandemic this past summer. That is when he started to notice all the plants.

He since began volunteering with the Giant Hogweed Mitigation Project, a group dedicated to reducing the threat of giant hogweed in the Grand River Watershed.

One site near Brandy Crescent in the Otterbein Road and Ottawa Street area was particularly bad, he says. He says he found hundreds of plants in that one spot alone.

This year he says he has found plants in the Woolner Trail area. The volunteer group is also concerned about an island in the river near Kolb Park.

The City of Kitchener confirms these are spots where the plant is known to grow.

Giant hogweed seeds float into the area from upstream, and the plant rapidly takes over areas around the Grand River, says Niall Lobley, the Director of Parks and Cemeteries at the city.

Each year the city will typically receive reports of plants in 20 to 30 locations, and most of those reports come from one or two people, says Lobley. And each year the city hires a contractor to remove the weeds when they receive reports of the plants on city property. He says they also proactively target known areas prone to the weeds or where people are most likely to encounter them.

Lobley says the city is planning to develop an invasive species management plan and expects giant hogweed will be included in it.

Kuipers says he was told to stay away from the plants by the city, so he began putting caution tape around the areas where he found the plants.

“When I see kids have close calls with this — it’s going to scar them,” says Kuipers. “So few people know the risk, and I’ve seen so many close calls in the last year, it’s not funny.”

Giant Hogweed sap contains natural compounds called furanocoumarins, says Francois Tardif, a plant biology professor at the University of Guelph.

Once furanocoumarins penetrate the skin and access a person’s cells, UV rays will cause the molecule to react with the cells’ DNA and trigger programmed cell death. This results in swelling, blistering, reddening and possibly scarring, says Tardif.

Tardif says giant hogweed is a monocarpic perennial, meaning that it lives more than one year and dies after it flowers.

“Giant hogweed typically flowers in years three to five,” says Tardif. “Before that it grows as a low stature rosette that may be hiding in other vegetation, escaping management efforts if they are aimed only at tall mature (plants),” he writes.

The Giant Hogweed Mitigation Project keeps photos on its Facebook group page to help people identify giant hogweed while it is still small. John Kemp, the founder of the group, says that giant hogweed can be safely dug out of the ground with a shovel at this stage, with proper footwear and clothing.

Kemp and other group members train people to identify the plant, and how to remove it safely.

The group advertised a public event on Facebook to dig small giant hogweed plants out of the Brandy Crescent patch this past Saturday.

This City of Kitchener asks anyone who sees giant hogweed on city property to stay far away, not to attempt to remove the plant and report it.

“There is really nothing the public can do except report,” says Lobley.

Ontario’s laws place responsibility for noxious weed removal on land owners. Islands in the middle of the Grand River may not have clear ownership and those often are hot spots for collecting giant hogweed plants and acting as a seed source, distributing seeds downstream. Volunteers with the Giant Hogweed Mitigation Project often target these islands.

The City of Kitchener cannot address giant hogweed problems on private property, says Lobley. The seeds come from upstream, so there is a constant fresh source of seeds, and the problem returns every year.

“A long-term strategy would have to look at the whole of the watershed,” says Lobley. “The City of Kitchener cannot manage this alone.”

City of Kitchener phone number to report giant hogweed: 519 741 2345

More information on the plant:



Leah Gerber’s reporting is funded by the Canadian government through its Local Journalism Initiative. The funding allows her to report on stories about the Grand River Watershed. Email lgerber@therecord.com

Leah Gerber, Local Journalism Initiative Reporter, Waterloo Region Record