Bull Thistle

Weeds

spear thistle, bur thistle, plume thistle, roadside thistle, Cardus vulgare, Cirsium lanceolatum

Cirsium vulgare


Bull thistle is a clumping biennial that forms a thick taproot in its first growing season. The leaves of bull thistle are covered with 'soft' hairs and needle-like spines on the margin. Leaves of seedlings are not deeply lobed like mature leaves. This is the thistle you stepped on in your bare feet as a kid. Bull thistle will form an erect branched habit in its second season on which the large purple blossoms will form if left unmowed.

  • Crops Affected: Turfgrass

    Management

    Bull thistle is associated with low maintenance areas and roadsides. Because bull thistle is a biennial it relies on reproduction by seed. Plants that establish during renovation will persist for up to two seasons. Consistent mowing and good nitrogen fertilization will likely create a turf that resists infestation from a second generation.

    Similar Species

    Bull thistle, a biennial, is often confused with Canada thistle but can be distinguished by the profuse hairs present on the upper leaf surface. Bull thistle will often appear as a single specimen, whereas Canada thistle will almost always be present with several daughter plants.