Canada Thistle

| 3/9/2013 12:50:22 AM

Tags: Pests, Canada Thistle, Thistle, Garden, Plant, Quackgrass, Couchgrass, Sheryl Normandeau,

Canada thistle in winter 

What are your worst plant enemies? 

I have a severe problem with quackgrass (aka couchgrass, Elymus repens), which I have struggled with for over a decade. I don’t use any chemicals in my garden, so it means a great deal of elbow grease is necessary. While I have made significant inroads, I cannot ever let my guard down!  

One plant enemy I am so glad I don’t have in my garden is Canada thistle (Cirsium arvense). Are thistles a problem where you live? 


  • Canada thistle is not a native of Canada. It actually has its origins in Mediterranean Europe. 
  • Another common name for Canada thistle is creeping thistleas in, it creeps you out with its insane root system.  
  • Each plant can produce up to 5,000 seeds. 
  • Each seed can remain viable in the soil for up to 20 years. 
  • Just 8 to 10 days after flowers emerge, plants can already produce viable seed. 
  • Canada thistle reproduces by seed AND by vegetative cloning a double whammy. 
  • New plants can form from the tiniest of root segments – just 1/8 – 1/4″ thick and 3/8″ long. This is why pulling and digging don’t work very well. 
  • The tap root of each plant can reach 20 feet underground in a single growing season. Isnt that incredible? 

(For more information about Canada thistle, check out 

nebraska dave
3/19/2013 12:48:08 AM

Sheryl, congrats on being a featured blog in GRIT Country the digital magazine in the off month of GRIT magazine's regular edition.

hans quistorff
3/17/2013 7:17:36 AM

This is my method for dealing with Quack Grass and other weeds that propagate by running roots. Mulch heavy with hay or grass. when the weed first pushes through the mulch, rake the mulch off and use a closely spaced tine fork to lift the roots from the soil with as little breakage as possible. It may require prying the tines back and forth a few inches apart until an area is loose enough to get under and lift the roots. You are cultivating the area for future planting so the work is not wasted and it gets easier each time. return and add to the mulch and repeat. When you can separate the mulch from the few weeds coming up by hand and pull the offending rhizome it may be safe to start transplanting hardy plants like cabbage into the mulch. This method has allowed me to develop several large planting areas from 50% quack grass pasture. But then I have 3 acres of former pasture to cut and use as mulch.

fran blank
3/15/2013 3:27:30 PM

I have daelt with quackgrass by following a recommendation I found in Start With The Soil by Grace Gershuny. 1. Sow buckwheat thickly - 3 pounds per thousand sq.ft. as easly as possible, after all danger of frost is past. 2. Just as it starts to bloom, cut is down and till it in. Replant with buckwheat right away. 3. When the second crop of buckwheat begins to flower cut it down and till it in and replant with winter rye - 2.5 pounds per thousand sq.ft. 4. Allow the rye to grow over winter and work it in as early as possible in the spring. This technique exhausts the nutrient reserves of the couchgrass/quackgrass roots. Hope this helps!

nebraska dave
3/12/2013 4:39:07 AM

Sheryl, I shudder at the mention of Canadian Thistle. We had patches of it on my Dad's second farm that he bought when I was in high school. Dad wasn't never an advocate of using harsh chemicals. He never got caught up in the new age chemical farming. He never really had huge farms either. The last farm was only 114 acres and half of that was pasture. His final battle with the dreaded Canadian Thistle was to buy some sheep. He said the sheep would eat the thistle before any grass. My uncle had a couple patches of Morning Glory in his fields. I hated hitting those spots when cultivating the corn. It would plug up the cultivator which required stopping and pulling the vines out of the machinery. Then there was the nasty cocklebur. Back in my days on the farm it was common practice to walk the corn rows with a corn knife or a hoe and chop out the cocklebur. It was a hot sweaty job and required wearing a long sleeve shirt to keep from getting cut from the corn leaves. Those leaves would give a cut just like a paper cut. Walking in that soft dirt all day would wear me totally out. I'm glad my garden doesn't have any of those noxious weeds.

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