Asked May 5, 2020, 9:48 PM EDT

I have been dealing with these particular weeds in my mulch beds. I have used Preen, various weed killers and removed them and more seem to grow. I would appreciate any suggestions on how to get rid of them. Thank you.

Howard County Maryland

1 Response

This looks like Canada thistle (Cirsium arvense). It is a non-native invasive plant and it is very difficult to get rid of. Pulling will not dent it. Never till a bed of it, because each tiny piece can generate a new plant.

Here is our webpage about Canada thistle: http://extension.umd.edu/hgic/canada-thistle Be sure to use the links provided to get information on control options.
If you dig these plants, you must get every bit of root. If you spray with a systemic herbicide containing the ingredient glyphosate, that can kill the roots, but expect to spray more than once.

In addition, take a look at our video about controlling Canada thistle. https://youtu.be/zDhB4LBEJOE