Volunteers take early action against invasive giant hogweed in Waterloo Region

A dedicated group of volunteers is taking proactive measures against a looming environmental threat: giant hogweed. CTV's Hannah Schmidt reports.

As spring unfolds across Waterloo Region, a dedicated group of volunteers is taking proactive measures against a looming environmental threat: giant hogweed. 

The invasive plant, known for its rapid spread and harmful effects on humans, is being targeted by the Giant Hogweed Mitigation Project, a community-driven initiative aiming to curb its growth before the summer months.

The group lined the shore along the Grand River in Kitchener Saturday, armed with shovels.

“There’s probably 10,000 plants in this patch, so we’ll be here for a while,” said John Kemp, founder of the Giant Hogweed Mitigation Project. “We’re digging the plants out, leaving them where we found them. After we cut the root off and cut the crowns from the plants, then they won’t grow. ”Their mission? To dig out as many plants as they can.

“We do that in April because it’s cool enough. So, our normal clothes become our protective equipment, so we don’t get the sap on our skin. Wearing gloves and boots is sufficient,” explained Kemp.

A dangerous invader

Giant hogweed originates from southwest Asia.

Now common in southern and central Ontario, the plant is often seen growing along roads, ditches and streams, as well as fields and woodlands.

Its sap contains toxic compounds that, upon contact with human skin and exposure to sunlight, can cause severe burns, blisters and even long-term scarring. In some cases, contact with the eyes can lead to temporary or permanent blindness.

“It affects your skin and removes your ability to protect yourself from sunlight,” said Kemp. “So, after about six hours of contact, your skin becomes super sensitive to ultraviolet light...when the skin grows back, it may actually be a slightly different colour.”

According to Wellington-Dufferin-Guelph Public Health’s Health Protection Operations Director, Phil Wong, the clear watery sap of giant hogweed can also cause long-term scarring and in some cases, permanent blindness.

“Purplish scars may form and persist for many years,” Wong said in an email to CTV News. “Eye contact with the sap has been reported to cause temporary or permanent blindness, although evidence of permanent blindness due to giant hogweed exposure remains unsubstantiated by existing research.”

The plant can grow up to 20 feet tall. Each plant is capable of producing between 20,000 and 100,000 seeds, according to Kemp.

“It takes about four years or three years to get to maturity,” he said. “And then it deposits all those seeds and about 90 per cent of them will grow in the first year...so the increase of the population is pretty high.”

Kemp said he keeps an eye on the Grand River watershed and, specifically, the area between Waterloo Region and Brantford.

“If you’re in southern Ontario and you’re on a water course, chances are it’s going to be on the shore,” explained Kemp. “So, you got to know what it looks like and then just walk around it. We’ve determined that it’s growing between 200 and 500 per cent per year. So, it’s definitely on the increase. The reason for the spread of the seeds is predominantly ice flows and human interaction.”

But he said the biggest threat to the public isn’t the spread of the seeds alone, it’s the lack of knowledge.

“If you don’t know what the plant is and you don’t know it can hurt you, then you’re at major risk.”

Collaborative efforts and public education

Education remains a cornerstone of the group’s mission. 

By informing the public about the dangers of hogweed and how to identify it, the project empowers residents to take part in monitoring and reporting sightings. 

Kemp encourages community members to join their Facebook group, the Giant Hogweed Mitigation Project Community, to stay informed and involved. 

In an email to CTV News, the City of Kitchener said they have “an annual monitoring and treatment program to manage giant hogweed, prioritizing areas where the plants’ proximity to existing city trails and parks poses a safety risk.”

While getting shovels in the ground works in the short term, Kemp said it’s about digging further to get to the root of the solution.

“We need to do education, which is one of our thrusts with the Facebook group and a shared Google Drive with pictures so we can show people what the plants look like in each month.”

Similar species to be aware of

Hogweed can be confused with other similar-looking species.

The GRCA said it’s not uncommon for people to mistake the plant for its look-a-likes.

Those include: Cow parsnip, Wild parsnip, Purplestem angelica, Woodland angelica, Valerian, Lovage and Queen Anne’s Lace (or wild carrot).

Kemp said there’s ways to tell these different plants apart from one another.

“Wild parsnip has a yellow flower and is maybe four or five feet tall. A cow parsnip has a smooth stem and smaller flowers and is probably only about seven feet tall. The giant hogweed has a great hairy stem, coarse hairs with purple blotches on it and it’s very large.”

What you can do

If you find hogweed growing in your yard or community, contact the Invading Species Hotline at 1-800-563-7711 or report online here. www.invadingspecies.com/Report.cfm

For GRCA properties, email the agency’s Land Management Department.

Sightings can also be reported directly to your municipality. The GRCA shared the following contact information:

• Brant County: Weed inspector at 519-449-2451
• Dufferin:  Dufferin County Building Services - 519-941-2816 ext. 2700 or email [e-mail]
• Guelph: Report an invasive species.  Contact Public Works at 519-837-5626 or email [e-mail]
• Haldimand: Contact the bylaw enforcement staff at 905-318-5932
• Halton:  By-law enforcement officers and area weed inspectors.
• Hamilton: If you find giant hogweed, call 905-546-2489
• Oxford: Weed inspector at 519-539-9800, ext. 3132.
• Perth: Weed inspector at 519-291-2236.
• Region of Waterloo: In North Dumfries, Wellesley, Wilmot and Woolwich townships contact the Region’s Area Weed Inspectors at 519-575-4400. In Kitchener, Cambridge and Waterloo contact city hall.
• Wellington: Weed inspector at 226-962-4007