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Getting Rid of Canada Thistle #924191

Asked February 03, 2026, 4:31 PM EST

For the last three years, I have assisted my son in battling Canada Thistle in his landscaping at the house he bought. No matter how fast we pull weeds, they keep coming back. I am trying to avoid using chemicals as the landscaping is on a hill and it would drain onto the driveway and then into the sewer system. If I remove all of the mulch and place some landscaping fabric down, replace the mulch, will that help? I have done some research and can’t seem to find a good approach.

Ramsey County Minnesota

Expert Response

HI Cynthia,

Canada thistle is very difficult to eradicate. The roots can go feet deep underground and plants spread by runners.

Here are some fact sheets that may be helpful:

https://extension.umn.edu/identify-invasive-species/canada-thistle

https://extension.psu.edu/removing-canada-thistle-from-the-home-garden#:~:text=Physical%20Control,if%20acceptable%20in%20your%20garden

This plant popped up in my city yard and when I was not able to stop the plants from spreading by digging I used a pruner or a sharp spade to sever the top from the roots. Using a herbicide that was labeled for thistle or for all green plants I immediately sprayed ONLY the raw stump of the roots with the chemical. The herbicide was sucked up by the roots where it should be confined, and the plants finally died.

I hope this is helpful. Thanks.

MJ Replied February 06, 2026, 4:59 PM EST

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