Growing Radicchio

Radicchio is a cool season crop grown alongside broccoli, cabbage, and cauliflower. The radicchio is the bright purple head in the middle of this winter harvest.

Radicchio grows best during the cooler seasons—spring and fall. Set plants in the garden in early spring (as soon as soil can be worked). For a fall crop, tuck transplants into soil in midsummer in colder zones and early fall in regions with a mild winter. Radicchio grows best in full sun during cooler weather; in summer, plants benefit from afternoon shade. Established plants can withstand frost.

When planting, space plants 8 to 10 inches apart. If you know you like radicchio, you’ll want to plant 5 to 6 plants per person. Mix plenty of organic matter into soil prior to planting time. Like lettuce, radicchio is shallow-rooted and benefits from consistent soil moisture. Organic matter helps to hold moisture in soil. Infrequent watering increases bitter flavor of leaves and also causes uneven growth. Irrigate plants deeply and frequently, providing roughly 1 to 1.5 inches of water per week. The most critical watering period occurs 7 to 10 days before heads mature. Mulch soil around plants to retain moisture and limit weed growth.

After planting, fertilize with Bonnie Herb & Vegetable Plant Food. This organically based fertilizer is low in salt and won’t cause ugly brown leaf tips. Avoid over-fertilization with nitrogen, which can cause plants to bolt and become intensely bitter. Heads form best in cool weather; cooler temps sweeten leaf flavor. In all but the coldest regions, allow crowns to remain in soil after harvest. Mulch the crowns as cold weather settles in. Plants may produce a second harvest in spring and will likely do so in milder climates.

Some varieties of radicchio tend to bolt but our round Red Chichory variety is bolt resistant. Most gardeners find that radicchio grows with few problems.

Harvest individual leaves any time. Heads are ready for cutting when they’re firm to the touch, similar to iceberg lettuce. To harvest, cut the entire plant just above the soil line. Harvest heads when they’re young, picking at whatever stage you want: kiwi, orange, or grapefruit size. Older heads become more bitter and tough. Don’t expect all heads in a crop to form at the same time.

Once heads reach maturity, they won’t continue to enlarge but will instead develop a core, the start of a flowering stem. When this core forms, flavor becomes intensely bitter. Fall-grown crops hold heads better and longer than spring-grown plants. When stored in the refrigerator in a perforated plastic bag, heads typically last 3 to 4 weeks.

Plants handle fall frosts well. In cold climes, snow-covered, frozen heads can be harvested and consumed. Thaw slowly and discard outer, cold-damaged leaves.

Mix some chopped radicchio leaves in with Romaine or other green lettuce for additional color, flavor, and nutrients in your salad greens.

You can eat radicchio raw or cooked and use individual leaves or an entire head. Serving leaves with salt counteracts the bitter flavor and draws out the high sugar content. Toss raw leaves with olive oil and salt for a simple side dish. Blend them with milder lettuces and greens for a fresh salad. Roast or grill chunks of radicchio until edges turn brown. You can even skewer entire heads and roast them on a spit. Sauté, bake, or flour and fry individual leaves. Count on radicchio to add color to pasta, soups, legumes, rice dishes, or omelets.

Raw or cooked, the bitter flavor pairs well with the acidic sweetness of balsamic vinegar. Other great flavor partners include butter, prosciutto, Italian cheeses, lemon, salami, and fresh shell beans. Use radicchio as a substitute for chicory or endive in recipes.

Core small radicchio heads, removing much of the center of the head, to create a leafy bowl for holding seafood, tuna, or chicken salad. Strongly cupped individual leaves form ideal individual bowls for serving mixed salads like fruit, potato, or seafood. On a buffet, use individual cupped leaf “bowls” to hold olives, cheese chunks, croutons, or toothpicks.