Weed of the week: Common groundsel (Senecio vulgaris L.)

June 7, 2010 in Extension

Common groundsel is one of the most prevalent weeds found in flower beds, around building foundtions and fence posts, and in lawns during May and June in Pennsylvania. This weed grows best in moist, fertile soils; but also persists in poor quality soils and in waste areas.

Common groundsel is an erect, branching, annual weed that grows to a height of 5 to 10 inches in non-mowed areas. This species is a member of the aster family (Compositae) and reproduces by seeds. The most characteristic feature of common groundsel is its deeply lobed, fleshy leaves (with sparse hairs along the midrib), and small (1/4 inch diameter) yellow flowers produced in clusters at the tops of plants. Like dandelions, common groundsel flowers develop into a pappus of white, feathery bristles with seeds that are wind disseminated.

Common groundsel plants appear in April, May, and June in central Pennsylvania, and tend to dry up and die during periods of heat and drought later in the summer. This species can be controlled with commonly-used commercial broadleaf herbicides. Control is best achieved when applied to foliage when plants are young and actively growing.