Radicchio is a type of leaf chicory (Cichorium intybus). Its white-veined red leaves make it a striking addition of flavor and complexity to salads and other dishes. You can always tame its bitterness by roasting or grilling.
A close cousin to Belgian endive and sugarloaf, radicchio is also known as Italian chicory. This cold weather plant is a popular ingredient in many Italian dishes, from risotto and strudel to soups and tapenades. It’s so popular, in fact, that each region of Italy has its own type of radicchio. Each varietal is protected legally, like Le Puy lentils, Bordeaux wine, and Champagne. The radicchio chicory we get in the U.S. is usually the Chioggia variety.
Chioggia radicchio looks similar to red cabbage. It will store well in your refrigerator for weeks, though using it sooner is better than later. Treviso radicchio is more elongated with more white than red, and it looks similar to large endive.
Tardivo is a curled-leaf version of Treviso coaxed into its unique shape through careful cutting, blanching, and regrowing methods similar to Belgian endive. Castelfranco radicchio has pale green leaves and red freckles. It is sweeter than other radicchios. Other varietals include Palla Rossa and Rossa di Verona.
How to grow radicchio
Like other chicories, radicchio is a perennial plant. You can cut heads off the top indefinitely. The quality of the harvests is said to deteriorate over the years, so you may want to add new seeds every so often. You can also use succession planting for an ongoing harvest.
Radicchio prefers loose, nutrient-rich soil with good drainage. Regular watering reduces bitterness. Radicchio can be grown in USDA Hardiness Zones 4-10, though it prefers zones 8 and above. Seeds should be planted ¼” deep and thinned to 12” apart.
When you start your radicchio plants depends on where you live. In warmer climates, radicchio is a cool-season crop planted twice each year. Start one batch in January or February for an early summer crop. Plant again in July or August for an early winter crop. This gives the seeds time to get established before the weather turns too hot or cold. Chicory grown in areas with scorching summers tends to bolt, making the leaves taste more bitter. These plants can tolerate temperatures in the low 20s (°F). Light frost makes them sweeter. You can protect them from lower temperatures with row covers, cold frames, and hoophouses.
Radicchio pests and diseases
Very few problems will occur for your radicchios, as long as they are well-fed and watered. All members of the chicory family are susceptible to the following: anthracnose, bacterial soft rot, bottom rot, damping-off disease, downy mildews, fusarium wilt, septoria blight, and white mold. Aphids, cabbage loopers, darkling beetles, flea beetles, leaf miners, thrips, and slugs and snails may feed on your radicchio plants. You’ll want to avoid overhead watering, as the leaves are prone to rotting. And brassica collars can thwart some of those pests.
Ancient folklore warned that eating too much radicchio would lead to dimming vision. Science has not found cause for those claims. Eating radicchio and other chicories will help combat intestinal worms, however. If you are a farm animal, that is.
Now you know.
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