Purple milk thistle, also called boar thistle, is an annual or biennial and a native of the Mediterranean area where it grows in disturbed soil such as wastelands, pastures, and roadsides. It is a member of the aster family (Asteraceae), and has a flower head is a bit over an inch in diameter and composed of central disc flowers surrounded by ray flowers that are white, pink, or lilac-purple. The bracts surrounding the flowerheads (involucre) are composed of hairy scales with a single terminal thorn. The flower heads appear in spring and continue blooming until mid summer. The stem has short soft hairs, is branched at the top, and carries thistle-like leaves that are pinnately di matted woolly hairs. The leaves are semi-evergreen and form basal rosettes about twelve inches across.
Type: annual or biennial
Bloom: White, pink, or lilac-purple flowerheads from spring to mid-summer.
Size: 3’ H x 1’ W
Light: Full sun; tolerates some shade
Soil: average to lean, medium moist, well-drained; drought tolerant once established
Hardiness: Zones NA
Care: Low maintenance
Pests and Diseases: None of significance