Spiny Thistle Cirsium horridulum

Purple thistle is a native herbaceous annual/biennial or short-lived perennial plant in the daisy family (Asteraceae) native to North America on the Coastal Plain from southern Maine to Florida and west to Texas. In North Carolina, it is abundant in the coastal and Piedmont areas and rare in the mountains. Its name comes from the Greek kersion which means thistle. It is often found along the edges of salt marshes, fields, shores, savannahs, roadsides, disturbed areas and waste places.

The plant grows 2 to 5 1/2 feet tall or even up to 8 feet and prefers sunny, open areas but can tolerate some shade. It grows in all types of soils, from moist to dry conditions, but it doesn't thrive in salt or brackish water. It grows best in sandy soil.  Propagate with seeds and sow in the fall or early spring. The seeds require light to germinate, so do not cover them with soil. Keep the soil moist until germination occurs. Once established it can tolerate periods of drought.

The showy heads of pinkish-purple or yellow to white disc flowers appear from May through August, attracting pollinators with their plentiful nectar. The bracts, stems and leaves are very spiny. Native bees nest in the dead, hollow stems, so gardeners are encouraged to cut back dead stems to 12 to 24 inches and allow them to remain standing until they disintegrate on their own. Read more about best practices for stem-nesting bees in this NC Extension publication.

Purple thistle is a great option in a meadow garden or naturalized area. Select with care, as this species may spread into areas such as lawns and flower beds. Some gardeners object to their spines but they deter deer and rabbits.

Quick ID Hints:

• White densely wooly underside of the leaves.

Insects, Diseases, and Other Plant Problems: No significant problems.