Rouge de Verona

Radicchio grows best in full sun to partial shade and prefers fertile, well-drained soil rich in organic matter. Keep the soil consistently moist and provide some afternoon shade during hot weather, as radicchio develops its best color and flavor in cool growing conditions.

For a spring harvest, start seeds indoors 4–6 weeks before the last expected frost, sowing ¼ inch deep. For a fall harvest, sow seeds in midsummer, approximately 10–12 weeks before the first expected fall frost. Keep soil consistently moist during germination.

Harden off seedlings before transplanting outdoors, approximately 2–4 weeks before the last expected spring frost. Space plants 10–12 inches apart in rows 12–18 inches apart.

Insect Pests

Radicchio is generally easy to grow with few pest problems. Occasionally, aphids, slugs, or caterpillars may feed on the leaves. Check plants periodically, handpick larger pests, and use insect netting or row covers if needed.

Diseases & Other Problems

Radicchio is generally trouble-free, although prolonged wet conditions can occasionally encourage leaf spot or rot. Provide good air circulation and avoid overhead watering when possible. Hot weather may cause premature bolting or increased bitterness, so plan your crop for the cooler temperatures of spring or fall.

Harvest radicchio when the heads are firm and well formed, cutting them at the base with a sharp knife. Remove any damaged outer leaves to reveal the colorful heads beneath. For best quality, harvest during cool weather. Store unwashed heads in a perforated plastic bag in the refrigerator, where they can remain fresh for 1–2 weeks.

CONSIDERATIONS:

Radicchio is a biennial that typically flowers and produces seeds in its second year. Allow healthy, true-to-type plants to overwinter, then collect the seeds once the flower heads have dried. Radicchio is insect-pollinated and readily crosses with other radicchio varieties, Belgian endive, and wild chicory. To maintain varietal purity, isolate flowering plants by at least ½ mile from other chicories, or use insect-proof isolation cages with managed pollinators.

HARVESTING SEED:

Allow plants to flower and set seed in their second year. When the flower heads have turned brown and dried, cut the seed stalks and allow them to finish drying in a sheltered location. Crush or rub the dried flower heads to release the seeds, then screen and winnow to remove the chaff. Dry thoroughly before storing.

SEED LONGETIVITY:

Radicchio seeds typically remain viable for 4–5 years when stored in a cool, dry, dark location. Properly dried seeds stored in airtight containers may remain viable longer, although germination rates gradually decline with age.