Look for an herbicide with aminopyralid, glyphosate, or chlorsulfuron on the ingredients list. Herbicides are dangerous chemicals, and they can cause irritation. Always read the warning label on your bottle of herbicide, and wear gloves and eye protection to stay safe.
If you pull the thistle and it doesn’t have any flowers on it, you can throw the stems in with your compost pile or yard debris bin. If you accidentally pull a thistle that has flowers on it, bag it and take it away to be burned. Flowering thistles can spread seeds even if they aren’t in the ground.
After using your mower on thistle, inspect it carefully and clean it off. If there are any seeds stuck to your mower, bag them and burn them.
Like mowing, you may have to allow your animals to graze multiple times throughout the year to keep the thistle from flowering. Goats are the most effective at grazing, but sheep, cattle, horses, donkeys, and llamas will also eat it.
It’s important to till as far down as you can. Shallow tilling will actually encourage the spread of Canadian thistle. On its own, tilling isn’t a very effective method. It works best when you follow up with an herbicide application.
Controlled burns don’t work very well on their own. They’re most effective when you follow up with an herbicide application. Never try to do a controlled burn on your own without the supervision of a professional.
Canadian thistle seeds are brown and only about 1 mm (0. 039 in) wide. They can be hard to distinguish from other seeds, so if you spot any seeds at all in your hay or straw, don’t bring it onto your property.
Try planting switchgrass, fountain grass, or reedgrass.
Some species of insects might be more suited for areas than others. It’s important to get a permit and check with your local laws before using a biological control method.
Once Canadian thistle is established, it’s really hard to get rid of. Prevention and early treatment are key.
