My Fight with a Minnesota Noxious Weed

By Karen Valerio, Hennepin County Master Gardener

I’ve lived in my house for over 20 years and my biggest weed problem has been Creeping Charlie.   I hate Creeping Charlie.  I’ve tried the borax solution, carefully measuring the square footage and applying the right mix of solution.  It didn’t work.  Now it’s invaded my lawn and flowerbeds.  With dogs, though, I don’t want to use herbicides, so I just keep pulling it up.  At least it comes up easily!

Then I found this spiny, prickly plant and it really hurt my hand to pull it out.  Next thing you know, it’s e-v-e-r-y-w-h-e-r-e.  It hurts to step on it.  It hurts if I accidentally sit on it (ouch).  It hurts to touch it.  It grows tall and forms flowers.  It’s Canada Thistle.

I’ve pulled and pulled and pulled.  I have more and more and more.  So what is Canadian Thistle?  The Midwest Invasive Plant Network ( has some disturbing news:

  • One plant can produce up to 5,000 seeds, and seeds remain viable in the soil for up to 20 years.  This means that when you weed and turn the soil, you expose seeds to the light and air so they can germinate.
  • It reproduces clonally by creeping roots that grow laterally in soil, up to 10 to 12 FEET per year. Also produces taproots that may grow more than 6 FEET deep. Readily regenerates from root fragments.  So if you pull it and don’t get the entire taproot, it will just grow back.
  • Once it has established it spreads quickly, forming mono-specific stands and replacing native plants.

Once I asked a weed expert about Canada Thistle and he told me that I’ve got a problem.  So how does one control it?

  • Get it when it’s small!
  • If it grows tall, pull it out.
  • And yes, I do use an herbicide selectively on the small plants, as long as they aren’t growing right next to a plant I want to keep.  *Sometimes I cut a tall plant down, spray it with herbicide and cover it with leaves so the dogs can’t get it.

I do this every week!  Every single week during the entire growing season.

This method is actually helping, a lot.  The problem is that I can’t keep up with every section every week.   But I’m diligent.  Never give up the fight!

Oh, did I tell you about the garlic mustard I discovered growing in the back of the yard?  That’s another noxious weed.   Makes me really appreciate that Creeping Charlie.

*Note:  Always follow package directions.  It’s the law and the final word on how to use the product.


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