My hatred of the Canadian Thistle is high, right up there close to my hatred of mosquitoes. The name Canada Thistle (Cirsium arvense) is misleading because the nasty plant did not originate in Canada, but in Europe. Ae terribly invasive plant, it has become a problem around the world.
It spreads not only by its many seeds that are blown in the wind, but also via its extensive root network spreading underground. The plant has nasty, sharp, spines on both its stem and its leaves. It is a very persistent plant and even though I have been cutting it down every year before it blooms, it keeps coming up. I have been doing this for over forty years, without any visible decline in its numbers. (I won’t use poisons).
When we first moved to the Valley, I used to cut the thistles down with a hand scythe that once belonged to my grandfather, but now I use a gas lawn trimmer with a metal blade. It is faster and a little less work. Cutting the thistles down is part of just cutting all of the grasses in my pasture to make hay. I no longer have animals to feed the hay to, but I use the hay in my garden for mulch.
The spiny leaves on the thistles remain sharp and nasty even when they become “hay.” Many a time while spreading the hay around, I have gotten small painful splinters in my hands from the dry old thistle leaves. Thistles are really hateful plants.
In pulling up the thistle plants that come up in my garden, I have sometimes found them with vertical roots more than 18 inches (45 cm) long, and I don’t know how much further down they go before they hook on to their horizontal roots, see photo below, My foot is 12 inches (30 cm) long.
To summarize: I hate Canada Thistles.