
Although Creeping Thistle can be beautiful while in bloom, its aggressive nature isn’t so beautiful.
What’s tall, prickly, and extremely persistent? Canada thistle, but Diana Baragar — founder of the Thistle Patrol — would prefer we call it by its other common name: creeping thistle. “Calling the plant Canada thistle gives the impression the plant is from Canada, but it was introduced here from Europe,” says Diana. Once the plant arrived from Europe it began to spread and colonize, out-competing native plants for space and resources. The weed is now widespread across Canada and locally it is prevalent in Edmonton’s natural areas.
It is quite possible that Diana holds the world record for most creeping thistles pulled by human hands; a record that comes from 15 summers of pulling the invasive weed. She organized the first Thistle Patrol pull in 1998 in response to pesticides being sprayed in Mill Creek. Diana recognized that along with the creeping thistle, the native plants growing in the area were also being killed by the pesticides, and she committed to pulling the weed to stop the spraying.
When I asked Diana if she could estimate how many creeping thistle she has pulled over the years, she was hesitant to give an answer. “I have no idea,” she said. “If I knew the answer to that question I would probably be taken aback.” Considering we had worked together for an hour pulling creeping thistle and in that time managed to amass three huge piles of the weed, I assume the number would be staggering. The number of thistles Diana has pulled continues to grow with her commitment to running the Thistle Patrol weekly during the summer months.
After one hour of pulling we had cleared most of a small bank on the southeastern edge of Mill Creek ravine. I could see the difference our work had made in this small area, but in the grand scheme of things I wondered if we were really making any longstanding impact. It was then that I met Ed Retzer — a man in his 80’s wearing a green flat cap and carrying a scythe — who had been working away from me on the upper part of the bank. He has been Diana’s most committed helper over the last ten years. He reminisced of his days as a child visiting Mill Creek when the area around the ravine had been farmland, and it was obvious the area holds meaning for him.
Ed continued to tell stories of his childhood, and around 30 minutes later he was on the topic of the uses of hydrogen peroxide. While I enjoyed listening to his stories, what I was really looking for was the reason he had dedicated ten years of his time to pulling thistles. I used a small lull in his story to interject my question of why he had dedicated so much time to this cause. “I wouldn’t be doing this every week if I thought it was a waste of time.” Ed said. “For every weed we pull we prevent hundreds of more seeds from getting into the soil, and next year the thistles won’t be as bad.”

The long taproot of Creeping Thistle gives it the upper edge over native plants growing in the area.
Ed is right — an ounce of prevention is worth a pound of cure. Although we had only cleared one small bank of the creeping thistle, we had prevented thousands of seeds from being dispersed in the soil, and we had reduced the need to spray herbicides in the area. We had made a much bigger impact than just a small section on the southeastern corner of Mill Creek. Our conversation finished with discussing need to get more people involved in helping to control invasive weeds. “If everyone took one hour a week to pull some weeds in our natural areas, think of the difference we could make,” Ed said.
“Weeding for Wildflowers” is the slogan on the small signs Diana sticks into the ground near the area the Thistle Patrol is working. Since creeping thistle is a such a competitive plant it can easily overtake our natural areas like Mill Creek, reducing the biodiversity of other plants present. This in turn reduces the biodiversity of other organisms as they can no longer use the area the thistle has encroached on for nesting or feeding. Perhaps the most rewarding part of the evening was clearing the creeping thistle away from some native Canada anemone trying to grow in the area that was in danger of being choked out. Knowing this native plant can now continue to grow made the hour spent pulling more than worthwhile.

Canada Anemone, a much more desirable plant to have growing in Mill Creek, is rescued from the onslaught of Creeping Thistle.
If you would like to help with the Thistle Patrol weed pull in Mill Creek, Diana, Ed, the native plants, and all the organisms we share Mill Creek with would be grateful. The pull takes place every Tuesday night for one hour at differing locations in the ravine. It’s great exercise, great conversation, and a chance to enjoy the beauty of Mill Creek while working to protect it. To be placed on the contact list or for more information please email engedmonton@gmail.com. Or, if you are interested in organizing your own weed pull in one of Edmonton’s natural areas you can visit the Partners in Parks page on the City of Edmonton website.

Before and after photo of the small bank Diana and I cleared of thistle, preventing the release of thousands of seeds.

Myself and Master Naturalist Colleen Raymond are all smiles at the satisfaction of pulling invasive Creeping Thistle.
Photos: Jason Teare
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