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Canadian thistle in mulch totally taking over #869635

Asked May 22, 2024, 2:43 PM EDT

I have read the article on farm care of canadian thistle. Mine is just all over my garden and wondering best way to control. We have started picking, spraying with strong vinegar, and baking soda and placing cardboard down with mulch on top. We picked it out last fall and it is just back this spring. Any other ideas I would greatly appreciate Thanks Cyndie

Hennepin County Minnesota

Expert Response

Hi,

Thanks for your question.

UMN Extension has a great web page with information on thistle. The first step is to make sure that the thistle in your garden is Canadian thistle and not a different kind. Canadian thistle is designated a noxious weed by the Minnesota Pollution Control Agency and there's a protocol for notifying the MPCA and disposing of weed parts.

The Extension web page outlines actions you can take to try to eradicate Canadian thistle from your property. Effective practices include hand pulling (although note that small plant parts left in the ground can grow the following season), mowing before the plant goes to seed (probably not feasible in your garden), and direct application of a post-emergent herbicide such as 2-4D, triclopyr or glyphosate. Eliminating Canadian thistle is a multi-year process.

Good luck!!

Ellen Tveit Replied May 22, 2024, 6:38 PM EDT

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