Want to try something different in your garden next year? Cardoon might be worth a venture, even though it does a better job of looking pretty than producing delicious cardoon hearts in Kansas.
Cardoons are similar to globe artichoke, but the plant is considerably larger and somewhat hardier. It can grow up to 5 feet tall by 6 feet wide with silvery-green, thistle-like leaves. Long stems are topped with vibrant purple flowers that are also thistle-like. Cardoons can only be grown as an annual here in Kansas but are hardy perennials in USDA Hardiness Zones 8-14 (Lawrence is a Zone 6).
The prized parts of the cardoon are the stalks and tender leaves. Both may be consumed raw or cooked, with the stalks (hearts) sometimes being blanched like celery. They are popular in Mediterranean countries and other parts of southern Europe and grow like weeds in California.
To grow cardoon, start seeds indoors in late winter or very early spring. Transplant seedlings outside after all danger of frost has passed. Seeds could also be planted outside after the last spring frost, but these plants will not reach the size of plants that are started indoors and are less likely to produce blooms. Give the plants plenty of room to grow.
Several varieties of cardoon are available, including Tenderheart, Gigante, Bianco Ameliore and Bianco Avorio. Spineless varieties are generally preferred over those with spines.
Cardoons are typically harvested about four months after planting. The blanching process takes about one month, so if you transplant seedlings outdoors in May, you will want to begin the process in August.
To blanch cardoon stalks, tie the leaves up and wrap the stalks with burlap or paper, or pile straw or soil around them. After four to five weeks, remove the wrapping or mulch. Cut the plant just below the crown and trim the leaves. The blanched stalks are the hearts.
Cardoon hearts are typically 18-24 inches in length and 2-3 inches in diameter when harvested, although they may be smaller in Kansas because of the growing conditions.
Once harvested, cardoon hearts should be refrigerated with high humidity. They will typically keep for two to three weeks after harvesting.
Some reports suggest that cardoon stalks may become bitter when grown in hot conditions.
Of course, cardoon can always be grown for purely ornamental reasons, also. A grouping of them is likely to stop traffic.