PLANTING INSTRUCTIONS

Growing radicchio can add a splash of vibrant color and distinctive flavor to your garden. This Italian chicory vegetable is prized for its beautiful burgundy-red leaves with white ribs and its unique bitter-sweet taste that adds complexity to salads and cooked dishes. Radicchio forms compact, cabbage-like heads and is both ornamental and nutritious, packed with antioxidants and vitamins. With proper care, you can successfully grow this sophisticated vegetable in your home garden.

• Best Time to Plant: Radicchio is a cool-season crop that performs best in temperatures between 45°F and 75°F (7°C to 24°C). For spring harvests, start seeds indoors 4 to 6 weeks before the last frost date and transplant when seedlings have several true leaves. For fall harvests (typically more successful and less bitter), direct sow seeds in mid to late summer, about 80 to 90 days before the first expected frost. Fall crops often develop better color and flavor due to exposure to light frosts.
• Soil Type: Radicchio prefers well-draining, fertile soil with a pH between 6.0 and 6.8. Before planting, incorporate 2 to 3 inches (5 to 7.5 cm) of compost or aged manure to improve soil structure and nutrient content. Radicchio performs best in soil with consistent moisture but doesn’t tolerate waterlogging, so ensure good drainage. Adding a balanced organic fertilizer before planting will help establish healthy roots.
• Spacing: When direct seeding, plant radicchio seeds 1/4 inch (0.6 cm) deep. Space seeds approximately 2 inches (5 cm) apart in rows that are 18 inches (45 cm) apart. Once seedlings develop 2 to 3 true leaves, thin them to stand 8 to 12 inches (20 to 30 cm) apart, depending on the variety. For transplants, set them at the same depth they were growing in their containers and space them 8 to 12 inches (20 to 30 cm) apart in rows 18 inches (45 cm) apart.

CARE TIPS

• Watering: Radicchio requires consistent soil moisture to develop properly and minimize bitterness. Provide approximately 1 to 1.5 inches (2.5 to 3.8 cm) of water per week, adjusting based on rainfall and temperature. Water at the base of plants to keep foliage dry and reduce disease risk. Mulching around plants helps maintain even soil moisture and suppress weeds. Avoid letting the soil dry out completely between waterings, as this can increase bitterness.
• Fertilizing: Radicchio is a moderate feeder. After the initial pre-planting fertilization, side-dress with a balanced organic fertilizer or compost tea when plants are about half-grown (approximately 30 days after planting). Avoid excessive nitrogen, which can lead to loose heads and increased susceptibility to disease. A foliar spray of seaweed extract every 2 to 3 weeks can help boost plant vigor and stress resistance.
• Blanching: For milder-tasting radicchio with less bitterness, you can blanch the heads as they near maturity. When heads are almost fully formed, gather the outer leaves and secure them with a rubber band or garden twine, or cover the plants with an upside-down pot for 1 to 2 weeks before harvest. This limits light exposure to the inner leaves, reducing bitterness and enhancing the characteristic red color.

HARVESTING

• When to Harvest: Radicchio is typically ready for harvest 60 to 100 days after planting, depending on the variety and growing conditions. Harvest when heads are firm and fully colored, usually 3 to 5 inches (7.5 to 12.5 cm) in diameter. Fall-planted radicchio that experiences light frost often develops the best color and flavor. The heads should feel dense and compact when gently squeezed.
• How to Harvest: Using a sharp knife, cut the radicchio heads at ground level, leaving the root in the soil. In mild climates, the roots may regrow for a second, smaller harvest. Remove any damaged or discolored outer leaves before storage. For the best flavor and crispness, harvest in the cool morning hours. After harvesting, chill immediately to maintain freshness and reduce bitterness. Radicchio can be stored in the refrigerator for up to two weeks in a perforated plastic bag.

TROUBLESHOOTING

• Common Issues: • Bolting: Premature flowering triggered by heat stress or long daylight hours. • Tipburn: Brown edges on inner leaves caused by calcium deficiency or irregular watering. • Slugs and Snails: Nocturnal pests that create holes in leaves and leave slime trails. • Aphids: Small insects that cluster on leaves and stems, causing distortion and weakening plants.
• Solutions: • Bolting: Choose bolt-resistant varieties, provide afternoon shade during hot periods, and ensure consistent watering. Plant for fall harvests in regions with hot summers, as cooler fall temperatures reduce bolting risk. • Tipburn: Maintain consistent soil moisture, avoid high-nitrogen fertilizers, and consider adding calcium to the soil before planting. Ensure plants receive adequate water during head formation. • Slugs and Snails: Create barriers using copper tape or diatomaceous earth around plants. Set up beer traps (shallow containers filled with beer) or manually remove pests in the evening. Consider organic slug bait if infestations are severe. • Aphids: Spray plants with a strong stream of water to dislodge aphids or apply insecticidal soap. Encourage beneficial insects like ladybugs and lacewings. For severe infestations, use neem oil according to package directions.