thistle control

Asked July 15, 2019, 4:35 PM EDT

Hi I am trying to take control of a relatively large area of thistle without herbicides. I am cutting off seed heads (and bagging) and then I want to chop and drop or pile the rest of the plant. I have several different varieties of thistle. I'm wondering if leaving the plant on the ground is OK. I'm also wondering if immature flowers or seed heads could also just be cut and left on the ground. I am planning to cut plants to the ground every month or six weeks during the growing season. Do you think this is effective control (long term) I am by Smith Rock state park. thank you for any advice you have.

Deschutes County Oregon

1 Response

Mowing or physically removing seeds heads from thistles is a good way to limit seed production. Leaving the plants on the ground to decompose is fine. Immature flowers should still be bagged because there is likely going to be some viable seed production even if you continue to cut them off in a timely fashion. Mowing or cutting can control annual or biennial thistles, but has little effect on perennial thistles (i.e. Canada thistle). Systemic herbicide use is the best way to manage perennial thistles.