How to Grow Radicchio From Seed

Radicchio is a fall crop at heart. For most gardeners the sweet spot is a midsummer sowing, in June or July, so the heads mature and firm up as cool autumn weather sets in, which is exactly when radicchio tastes its best. In mild-winter regions you can also sow in late summer for a winter harvest. Spring sowings are possible but riskier, since heat and long days tend to make it bolt before it heads.

You can direct-sow radicchio or start it in pots and transplant, which many growers prefer for even spacing. Barely cover the tiny seeds, about a quarter inch deep, in rich, well-drained soil. Keep the soil around 60 to 68F and seedlings appear in 5 to 7 days. Set or thin plants to about 8 to 10 inches apart in rows a foot or more apart, giving each head room to fill out. Keep the bed evenly moist throughout.

Steady moisture and cool weather are the whole game with radicchio. Water regularly so growth never checks, mulch to keep roots cool and the soil damp, and feed lightly for healthy leaves. Climate sets the timing: in cold-winter regions like the Upper Midwest and Northeast, grow it as a fall crop and harvest before a hard freeze, while in mild-winter areas like the West Coast and the South it can head up over fall and winter. Heads set best as temperatures drop, so lean into the cooling second half of the season.

Radicchio is a tidy, upright grower that shares a bed happily with other cool-season crops. These four make especially good companions, and you can add any of them in one click:

Harvest once the head feels firm when gently squeezed, usually 80 to 100 days from sowing. For a sweeter, milder head, blanch it for about ten days first by covering the center to block light. Cut the whole head at the base with a sharp knife. If you leave the root and crown in mild weather, it may push out a second flush of looser leaves.

Radicchio is prized for its color and pleasant bitterness. Shred it raw into salads and slaws where its burgundy leaves and crunch stand up to bold dressings. Cooking transforms it: grill or roast wedges, or saute it, and the bitterness mellows into a gentle sweetness that is wonderful with pasta, risotto, or alongside rich meats. A soak in cold water tames the edge for raw use.

• Loose, leafy heads: usually too much heat. Time the crop to mature in cool fall weather so it firms up.
• Bolting: long warm days send spring-sown plants to flower. Favor midsummer sowings for a fall harvest instead.
• Bitterness: expected to a point, but blanch the head before harvest and grow into cool weather to keep it mild.
• Slug damage on lower leaves: keep mulch pulled back a little from the crown and handpick after wet weather.