Step 1. Correctly identify your plant.
Biennial thistle that can grow up to seven feet tall.
Leaves are three to twelve inches long, deeply lobed with prickly hairs on the upper leaf (distinct trait from other native or exotic thistles).
Plants produce solitary pink flowerheads at the end of each stem. Bracts (modified leaves below flower head) are needle like.
Photo source: www.kingcounty.gov
Step 2. Choose your method.
Hand pull or dig removing at least 2-4” of root. It is preferable to pull during the rosette (middle photo) stage, but mature plants can be pulled prior to going to seed. Seed any large patches of bare ground with native seed to prevent future weeds.
Bull thistle is a biennial plant, removal of rosettes in the late fall can help get a jump on next year’s crop of weeds!
Step 3. Repeat.
Seeds buried within the soil may survive for up to three or more years, so continued treatment is required.
To learn more about the biology of Bull thistle visit the web page below.