Milk thistle

Silybum marianum

This striking member of the daisy family has thorny, variegated foliage and purple blooms that resemble large thistles. Remove the blooms before seeds mature to prevent the plant from self-seeding and becoming weedy. When cut, the plant produces a white, milky liquid, which is how it got its name. The plant has been used for centuries as a treatment for diseases of the liver and gallbladder. In its native range, it is an annual, but it may overwinter in Zones 5-9.

Light: Part sun, Sun

Type: Annual, Herb

Height: 1 to 3 feet

Width: 2-3 feet wide

Flower color: Blue, Purple

Seasonal features: Summer bloom

Special features: Cut flowers, Low maintenance

Zones: 3-11

How to Grow Milk Thistle

Direct sow Milk Thistle seeds ½ inch deep into prepared seed beds after all danger of frost. Plant in groups of 3-4 seeds, spaced 30-36 inches apart.Germination is in 10-20 days. Thin to the strongest plant. Milk Thistle seeds can be started early indoors in peat pot containers.

Milk Thistle plants perform best in full sun, with fertile soil and moderate water. Will tolerate drought, any soil, and partial shade.Flowers attract bees and butterflies. When growing Milk Thistle as an ornamental, remove flowers after bloom to limit self-sowing. To save seeds, harvest flower heads in fall after seeds have dried; before they have begun to scatter. Milk Thistle plants are grown as annuals when started early indoors. Seed sown directly outdoors produce biennial plants in most climates, and will flower their second season.