How to grow radicchio
Overview
Radicchio is a chicory grown for its bitter, deep red leaves that form tight heads. It is a cool-season vegetable that requires consistent cool weather to develop colour and flavour. Growers must time planting so heads mature before heat triggers bolting.
Varieties
- Radicchio di Chioggia — The classic round, deep red head with white veins; reliable in Australian cool seasons.
- Radicchio di Treviso — Tall, elongated heads with a more intense bitterness; good for grilling.
- Radicchio di Castelfranco — Variegated green and red leaves; milder flavour, suitable for salads.
Soil Preparation
Radicchio prefers rich, well-drained soil with a pH of 6.0–7.0. Before planting, dig in well-rotted compost or aged manure to improve fertility and moisture retention. Avoid heavy clay soils that stay wet; if needed, raise beds for drainage.
Growing Guide
Sow radicchio seed 5mm deep in rows 30cm apart, thinning to 20cm between plants. Choose a site in full sun with well-drained soil. For best results, start in late summer or autumn so heads form in cool weather. Avoid transplanting if possible; direct-sown plants produce better roots and heads. Keep soil evenly moist, never waterlogged.
Sowing
Sow radicchio seed 5mm deep, 2–3 seeds per spot, and thin to the strongest seedling at 20cm apart. Seeds germinate in 7–14 days at 15–20°C. Direct sowing is preferred over transplanting to avoid root disturbance and bolting.
Care
Feed radicchio with a balanced liquid fertiliser every 2–3 weeks during active growth. Remove any yellowing or rotting outer leaves to improve air flow and reduce disease risk. No pruning is needed beyond harvest.
Companion Planting
Plant radicchio near chives, which deter aphids. Good neighbours include lettuce, spinach, and other cool-season greens. Avoid planting near fennel or strongly aromatic herbs that may inhibit growth.
Common Pests & Risks
Watch for snails and slugs, which chew holes in leaves. Use beer traps or copper tape around beds. Aphids may colonise leaf undersides; blast off with water or apply insecticidal soap. Downy mildew can occur in humid conditions; improve air flow and avoid overhead watering.
Harvesting
Harvest radicchio when the head is firm, compact, and about 10–15cm across. Cut the head at the base with a sharp knife. If left too long, heads may split or become overly bitter. Harvest before heavy rain or heat causes bolting.
In the Kitchen
Use radicchio raw in salads for a bitter kick, or grill halves to mellow the flavour. Store unwashed heads in the fridge for up to a week. The bitterness pairs well with citrus, nuts, and creamy dressings.
Troubleshooting
Bolting: heads go to seed in heat; plant in cool season only. Loose heads: caused by inconsistent watering; keep soil evenly moist. Bitter taste: normal for radicchio, but reduce by harvesting early or grilling. Yellow leaves: often from overwatering or poor drainage; check soil moisture. Slugs: use barriers or traps around young plants.