Identification

• Common sowthistle plants grow between 1 and 6 feet tall. A deep taproot supports the plant's smooth, dull green, hollow stems. Sowthistles have alternate hairless leaves with spiny margins. The leaves grow sparser and smaller toward the top of the plant. The lower leaves range between 4 and 8 inches in length and have deep wedge-shaped lobes, while the upper leaves have shallow lobes. The stems and foliage release a milky sap when broken. Rounded, 0.75-inch flowers composed of yellow rays bloom between late spring and the middle of summer. Hairy white seed heads replace the flowers.
  
  

Growing Requirements

• Sonchus oleraceus weeds grow best in moist, nutrient-rich, clay-loam or loamy soil with neutral or alkaline pH levels, and vary in size depending on how much moisture they receive and the level of nutrients in the soil. They thrive in full sunlight or partial shade. They do not grow well in full shade, however, and cannot tolerate acidic soil. Bees and flies pollinate the flowers between June and August. Common sowthistles reproduce by wind-borne seeds.
  
  

Benefits

• Young Sonchus oleraceus leaves are edible, particularly when they are harvested in the spring, but they are more palatable if you remove the prickly margins. You can add them to soups or salads or cook them like other leafy green vegetables such as spinach or collard greens. You can also eat the stems, but the Plants for a Future website suggests removing the outer skin first. The Chinese use Sonchus oleraceus parts in traditional medicines to stop bleeding, control infections and purify the blood, among other uses.
  
  

Control

• Sonchus oleraceus was one of the first species on the Ontario Weed Control Act's Noxious Weed List, according to Mike Cowbrough at the Ontario Ministry of Agriculture Food and Rural Affairs. It is also listed as a non-native pest species on the University of Florida IFAS Extension's Center for Aquatic and Invasive Plants website. You can remove the plants by manually uprooting them, but be sure to also remove the taproot so that the plant cannot sprout new shoots. Treat severe infestations with herbicides such as glyphosate.