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Radicchio Seed Starting Tips

Radicchio in garden seed starting

Radicchio grows best in the cool weather of spring and fall.

Radicchio has a lettuce-like head that colors to a deep rosy red as the weather grows cold in autumn or winter. The slightly bitter taste of radicchio sweetens with cooler day temperatures.

When to Plant Radicchio

  • Direct seed radicchio in the spring as soon as the soil can be worked or start seed indoors 8 weeks before the last frost in spring protected by a plastic tunnel.
  • Seeds germinate quickly even in cold soil and light frost will not harm the seedlings.
  • Avoid growing radicchio during the summer. Warm temperatures cause radicchio leaves to become bitter and pungent.
  • Radicchio matures in 75 to 110 days depending on the variety.

Radicchio Sowing and Planting Tips

  • Radicchio can be grown from seeds or transplants.
  • The seed is viable for 5 years.
  • Start indoors 12 to 8 weeks before the last frost or sow; transplant maturing seedlings into the garden 2 weeks before the last frost. Or direct-sow seed in late summer for autumn or winter harvest.
  • The optimal growing air temperature for radicchio is 45°-65°F (7-18°C).
  • Sow seed ¼ inch (6 mm) deep.
  • Sow seeds 2 inches (5 cm) apart; later thin seedlings 8 to 10 inches (20-25 cm) apart. Make sure there is good air circulation around maturing plants to avoid disease.
  • For intensive planting space plant 8 inches (20 cm) apart in a staggered pattern.
  • Radicchio grows best in full sun but can tolerate light shade.
  • Prefers a soil pH between 5.0 and 6.8.
  • Seed germinates in 5 to 7 days at or near 60°F (7°C)—but sometimes seed can take up to 2 weeks to germinate if the soil is cold.
  • Keep the soil evenly moist until seeds germinate then keep the soil moist until seedlings are well established.
  • Add aged compost to planting beds in advance of sowing; compost will feed the soil and aide moisture retention.
  • Avoid planting radicchio where endive and escarole have recently grown.
  • Make successive sowings every few weeks for an extended harvest.
  • Fertilize with an organic fertilizer such as fish emulsion at half strength.
  • Aphids, flea beetle, leafhoppers, armyworms, snails, and slugs can attack radicchio.

Interplanting Radicchio

  • Interplant radicchio with lettuce.

Container Growing Radicchio

  • Grow radicchio in a container at least 12 inches (30 cm) wide and deep.
Radicchio in garden seed starting
Radicchio ready for harvest
  • 8 weeks before the last frost in spring: direct-sow in a plastic tunnel or cold frame.
  • 8 weeks before the last frost in spring: start seed indoors for transplanting later.
  • 2 weeks before the last frost in spring: direct sow in the garden.

For Fall Harvest and Winter Harvest:

  • 6-5 weeks before the first frost in fall: direct-sow in the garden for a fall crop.
  • 5-3 weeks before the first frost in fall: direct-sow in a plastic tunnel or cold frame for winter harvest.
  • ‘Rossa di Treviso’ and ‘Rossa de Verona’ are standards.
  • ‘Giulio’ for spring crops.
  • ‘Augusto’ for fall and winter crops.

Botanical Name: Cichorium intybus

Radicchio belongs to the Compositae (Asteraceae) or sunflower family.

Also of interest:

How to Grow Radicchio

Radicchio Serving Raw and Cooking

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

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