How do I get rid of thistles in my yard?

Hello Nannette,

The secret is to cut the Flower Head off as soon as you see it, as they all have seeds that fly in the air like dandelions. If you dig them up and the seeds have not been taken off, you will have them grow again until all seeds have gone from the soil. Be Vigilant!

The key to controlling Canada thistle is to control it early before it has a chance to produce seeds and a serious network of rhizomes. Mowing or repeated cutting may be used to help prevent the spread by preventing the production of seeds and starving the plant. Mowing too late, however, can spread the seed.

Post-emergent applications of a systemic herbicide may be used. Fall is typically the best time for these treatments. Other good times are during the early bolting stage when plants are 6-10" tall and during the bud to flowering stage. In lawns, some herbicide options are 2,4-D, MCPP, MCPA, dicamba, triclopyr, carfentrazone, and quinclorac. Clopyralid is quite effective on thistle. Non-selective herbicides such as glyphosate/Roundup may also be used. Lawns should be properly maintained to promote a healthy, dense turf that will compete well with weeds.

Perhaps your site is not a lawn but instead a landscape bed. Many of these products are not labeled for this use due to the variety of species present. Be sure that the product you use is labeled for the intended area. Often times, careful spot treatments of non-selective herbicides are your only chemical option. Nearby sensitive plants may be covered with plastic prior to application. The plastic may be removed as soon as sprays dry. Applications may also be painted on using a brush or sponge. Be sure to read and follow all label directions carefully. Realize that multiple applications may be needed to eradicate this weed.

See if you don't find this informative, Nanette:

http://hyg.ipm.illinois.edu/article.php?id=73

You can use weed and feed. It is best to kill the thistle plants when they are first emerging--before they can reproduce their fluffy seed. I also pull up the ones I see--you have to get under the bottom leaves and pull them up by the root. I let the pulled up plants dry to dust in a hot sunny place!! It is best to use weed and feed when the plants are just beginning to grow in the spring but you can also use a weed and feed post emergent. I let them dry up in the sun until they are dust! Thistles will be an ongoing problem if there is a lot of thistle in your area and if you feed thistle to the birds. The birds will "plant" the thistle seed for you!