Culture
Winter hardy to USDA Zones 7-9 where this plant is best grown in moist, fertile, well-drained soils in full sun. Shelter from strong winds. Mulch in winter in areas near the northern part of the growing range. May be propagated by seed, division, root cuttings or suckers. Plants have a large and deep taproot. Cardoon is a Mediterranean-type plant that grows best in temperate climates with cool summers and mild winters. Cardoon is considered to be an invasive weed in some parts of California where it has escaped gardens (or Scolymus Group plants have escaped gardens and reverted), and it has in some cases formed large colonies in the wild. Cardoon may be grown for harvest of its edible leaf stalks and/or for enjoyment of its ornamental foliage. In areas where this plant is not winter hardy, it may be grown as an annual by starting seed indoors in February and setting seedlings outside near last spring frost date. Annual plants grown from seed may not reliably produce flowers, but the foliage is quite attractive.
Noteworthy Characteristics
Cynara cardunculus, commonly called cardoon, is a vigorous, columnar, upright, tender perennial that features prickly, razor-sharp, jagged, deeply-lobed, silver-gray leaves (white tomentose beneath) and thistle-like flowers. Although it is an edible vegetable (celery-like stalks may be blanched, harvested, steamed or braised and eaten), it is typically not grown in the U.S. for consumption as a vegetable, but is more often grown ornamentally in gardens for its attractive foliage and flowers (flowers bloom August-September in cold winter climates). It typically grows in a clump to 3' tall from which rise flower stalks to 6' tall topped with thistle-like blue-violet flowers. Cardoon is native to southern Europe along the Mediterranean. The flowers are quite showy on the plant or when cut for fresh or dried arrangements. Unopened flower heads may be harvested and eaten as artichokes (the fleshy lower area of the involucral bracts and the heart are edible), however the size and flavor is generally considered to be a poor substitute for the commercially grown globe artichoke known as Cynara cardunculus (Scolymus Group). For harvest of the artichoke-flavored stalks, the inedible leaves are tied together and the stalks are blanched (wrap burlap, corrugated cardboard or paper around them) when the plants reach 3' tall. Blanching helps to tenderize and improve stalk flavor. Stalks are then harvested (cut off at the ground) 4-6 weeks later.
Cardoon first came to the U.S. in the mid 1800s (Spanish settlers brought it to California and French settlers brought it to the Louisiana Territory). In contrast, Scolymus Group plants (once known as Cynara scolymus) are commonly called globe artichoke. These plants are tamer than cardoons and are less apt to spread weed-like. As a vegetable, Scolymus Group plants are primarily grown for harvest of the buds (artichokes) which are much larger and tastier than those buds found on cardoons. If Scolymus Group is grown from divisions, it will reproduce as globe artichoke. If Scolymus Group seed is planted, it will typically revert to the invasive species form (cardoons) as frequently happens when Scolymus Group plants escape gardens in areas such as California. Where winter hardy, the prime season for cardoon harvest is winter. Where not winter hardy, the prime season is early fall.
Genus name comes from the Latin name.
Specific epithet means resembling a small thistle.
'Rouge D'Alger' is an heirloom cardoon selection that was developed in Algeria. It has large, edible and ornamental leaf stalks that are brushed in pale red which contrast against the blue-green, silvery white leaves. Mature specimens will reach up to 3' tall and spread to fill a 3' area.
Problems
Aphids, snails, slugs and blackfly. Gray mold, powdery mildew and root rot.
Uses
Can make a striking accent in mixed borders, vegetable gardens, and Mediterranean gardens. The flowers and leaf stalks are edible.