Perennial Sowthistle is a creeping perennial with an extensive horizontal root system. It is reproduced by seeds and underground roots. The roots penetrate to a depth of 1.5 - 3 meters. The stem, which can grow up to 1.2 meters, is hollow, smooth and branches at the top. The plant also contains a milky substance inside the stem. The leaves alternate with a slightly toothed edge. Lower leaves have deep cut, backward pointing lobes. Leaves are approximately 15 - 30 cm long with upper leaves being smaller. The flowers are yellow in color; almost like a dandelion. They are 1.3 - 5 cm across. Seeds are small, brown, ridged and crowned with a tuft of fine hairs.
Tillage is the most effective way to control Perennial Sowthistle because it starves the root system. Start tillage as soon as possible after harvest, preferably with a cultivator. The next spring one of the following should be completed:
Start tillage early in spring and continue until freeze-up. Green growth should not remain above ground for more than a week.
Start tillage when the buds are in their early stage as this is when the plant is the weakest. Continue tillage until freeze-up.
Summerfallow until mid July to control other weeds. Then leave the Perennial Sowthistle undisturbed. When it reaches the early bud stage it should be sprayed with the appropriate chemical.