You might not know its name, but chances are you’ve dealt with Canada thistle (Cirsium arvense) at some point in your yard. I call it the Devil Weed, because, man, it is just straight-up evil. Thorny, persistent, invasive—those are just a few of the adjectives you could use to describe the Canada thistle (I have a few R-rated adjectives as well, but I’ll leave those to your imagination).
Canada thistle has an extensive and winding root system that can grow quite deep. It’s got green leaves that are lobed and covered in spikes, and it grows in a low pinwheel along the ground. If it goes to flower, it produces a cluster of purple balls that will eventually turn white like a dandelion head and disperse fluffy seed across the landscape.
A new plant is often able to grow from even a tiny piece of root left in the soil. And because of this, there is no quick and easy way to get rid of Canada thistle, especially without chemicals. Taking care of it organically is going to be a process. But it is possible.
Step one in getting rid of Canada thistle is to make your yard and garden a hostile place to this Devil Weed—and that actually means making your soil more fertile. While Canada thistle can actually grow anywhere, it thrives in less fertile soil and in open spaces without ground cover.
We’ve been dealing with an infestation of Canada thistle for the past three years at the Good Sweet Earth homestead. Just before we moved in, a new septic system was installed, which meant a whole lot of fill dirt being added to our front yard. Our first summer had us scrambling to figure out what to do with this wide-open area of bare soil. We settled on installing a large country garden, with new turf around it. Unfortunately, before we could really install the stuff we wanted (plants, flowers, grass seed), some real nasty stuff installed itself—including a large amount of Canada thistle. I mean, this area was prime real estate for this stuff: low-fertility fill dirt in an area with no ground cover.
So over time, we’ve begun making a dent in eliminating this nasty, thorny weed from our yard—but that’s the thing: it takes time. We’ve amended the soil, we’ve installed ground cover (both organic and non-organic), and we’ve been attack the plants themselves (without chemicals, of course).
And here’s how you go about attacking Canada thistle: Your first instinct might be to pull this thing out of the ground. But I’m here to tell you that pulling it is the wrong way to go about it. First of all, your fingers will pay the price for grabbing onto this thorny plant—even gloves are no match for the nasty pickers of the Canada thistle. Second, when pulling a Canada thistle out of the ground, you risk splitting the root; doing so will not only bring this nasty plant back, he’ll bring a friend—two will now grow in the place of the original.
Instead of pulling, I suggest cutting. Get a pair of scissors and cut it off at the ground level. Every few days, cut any new growth. By doing so, you’re forcing the plant to use its energy reserves to re-grow itself, but you’re cutting off the part of the plant that actually builds up new energy (the leaves). Eventually, you’ll see your Canada thistle population go down. It might not be quick, in fact, it’ll take a while, especially if you’re working on building up your soil’s fertility. But eventually, this Devil will be gone.
Steve & Corey Veldheer are organic yard & garden specialists in west Michigan.