A variety of thistles are found in turf. Like most, bull thistle is a biennial. It grows over the summer months. The leaves are alternate; blades are simple and form in a rosette. The leaves are unlobed to pinnately lobed. The bladetip is pointed and the margins are toothed with spines. The root is a fleshly taproot the first year and a fibrous root system forms the second year.
Individual bull thistle plants can be physically removed by cutting below the crown in early spring. Bull thistle should be removed prior to bolting and flowering to prevent seed development and distribution. Follow good turf management practices to create a dense competitive stand of turfgrass.
Source: Virginia Polytechnic Institute & State University