Cardoon

Cardoon is a large, spiny plant native to the Mediterranean region, with silvery to gray-green foliage and thistle-like purple flowers. It is grown both as an ornamental and as a food plant, since its blanched stems can be eaten. It is a perennial, but in cold climates it is treated as an annual.

Sowing. Start seeds indoors 6 to 8 weeks before the last frost. Sow 2 to 3 seeds about ¼ inch (6 mm) deep in each cell or container. Keep the soil moist until the seedlings emerge, then thin to one plant per cell when the first true leaves appear.

Transplanting. Move plants outdoors only after the danger of frost has passed.

Other ways to start. Plants can also be propagated by division in spring or by root cuttings in winter.

Site and space. Choose full sun and a spot sheltered from strong winds. Under ideal conditions, plants can reach 3 to 4 feet (91 to 122 cm) tall and 4 to 5 feet (122 to 152 cm) wide, so give them plenty of room.

Soil. Cardoon prefers rich, well-drained but moist soil.

Trimming. Remove older leaves as they droop to keep a tidy, vase-shaped plant.

Winter protection. Plants may go dormant in hot summers and die back in winter, so mulch heavily to help them survive. In very cold winters, apply a dry mulch.

Diseases that may damage cardoon include root rot, gray mold and powdery mildew. Insect pests include snails, slugs and aphids. Slugs, snails and blackfly may also bother it. In the eastern United States, Japanese beetles have been reported attacking it. Strong winds can damage the plant.

Spreading. In some regions it has spread to form colonies and is considered invasive. In mild climates it may become invasive, though this is not a concern in cold winter areas.

The part most often eaten is the young leaf stalk, which is blanched, harvested, cooked and eaten as a vegetable. Stems are often blanched for a few weeks before harvest by covering them to exclude sunlight. The flowers are edible but are not considered as suitable for eating as globe artichokes.

Be careful around the spines along the stems, although spineless cultivars exist. The leaves are also prickly.