Also known as cynara cardunculus, cardoon looks like one of the snooty society flowers from Disney’s “Alice in Wonderland.” Its silvery leaves are large and form a distinctive, upright sculpture-like shape. The dark pink blossoms resemble a thistle. What is most striking about cardoon is its size -- it can grow to 195 cm (78 inches) tall and wide, making this a difficult plant to grow in small gardens. Cardoon is a perennial in throughout the British Isles.
Select the site for the cardoon. Due to the size of the mature plant, this can be tricky. They do best in full sun all day, yet they need shelter from strong winds that might tear their leaves. The soil need to be rich and well drained. Several weeks before planting, dig in large amounts of compost or decayed manure.
Start cardoon indoors 8 weeks before the last frost free date. Fill a container with enriched potting soil. Plant the seeds 2.5 cm (1 inch) deep and water to settle the soil. Place the container in a sunny window. You should see the cardoon sprouting in 6 to 12 days. Water the seedlings regularly, but don’t allow the soil to become soggy.
Transplant the cardoons in mid-spring, after the last frost. Dig a hole that is wider than the container. Remove the plant carefully and place in the hole. Fill the hole with soil and tamp down carefully to remove air bubbles. Water to settle the soil.
Watch for the cardoons to bloom beginning in late spring or early summer. Water the plants regularly and deeply during the growing season and especially during prolonged dry spells. Once growth starts in the spring, apply a complete plant food; repeat again in midsummer.
Cut the whole stem low once the flower has faded. When the plant starts to look untidy, cut it back to just above the ground. Place a plant marker to indicate the location of the plant during the winter so you don’t disturb the flower.
Divide established cardoons in mid-spring. Dig up the plant and divide, making sure each section has adequate roots. Replant and water. Space cardoon at least 1.2 m (4 feet) apart.
You can also allow the flowers to dry on the plant and then cut them to use for dried floral arrangements. A close relation to the artichoke, cardoon is eaten by some as a vegetable. If growing it for consumption, give it a weekly liquid plant food.
Cardoon has sharp points on the flowerheads. Be sure to wear gardening gloves when handling it.