Excellent uniformity and high yield potential for summer harvests
Indigo has been the most reliable radicchio in both our hot- and cool-weather trials. It is remarkably sure-heading, very tolerant to tipburn, and resistant to bottom rot. The firm, 10-12.5cm diameter heads are a nice burgundy colour with good flavour. For spring, summer, and autumn production
CULTURE: For production, these varieties are vast improvements over older types, but are still not perfectly uniform or completely predictable. Although bred for specific seasons, it is still best to trial more than one variety, using succession plantings to determine which one suits your conditions. Radicchio is hardy and can be planted as early as the soil can be worked. It is a cool weather crop and grows best at temperatures of 15.5-18.3°C. Careful variety selection is important for hot weather plantings. Sow every 3 weeks for a continuous supply of fresh radicchio.
THERMAL DORMANCY: Radicchio seed can enter thermal dormancy when exposed to high temperatures above 25°C. Optimum germination results at soil temperatures of 15.5-20°C.
TRANSPLANTING: Sow in flats, 4 seeds/25mm, or in 19mm plug trays, barely covering seeds with fine vermiculite, 3-4 weeks before transplanting outdoors. Shade the flats on sunny, warm days if necessary to keep the soil surface cool, below 24°C, until germination. If sowing into flats, transplant 25-50mm apart into flats, pots, or cell-type containers about 2 weeks later. Harden seedlings by reducing water and temperature for 2-3 days before planting outdoors. Properly hardened transplants can survive temperatures as low as -6°C. Transplant 20cm apart in rows 45cm apart. Transplant shallowly so that the base of the plant will be slightly above the soil to discourage bottom rot.
DIRECT SEEDING: Seeds will germinate from 5-29°C, but the highest germination percentage will occur around 24°C, depending on the variety and seed lot. Sow seeds 25mm apart, rows 30-45cm apart. Cover seed lightly, about 3mm, and firm soil gently. Thin to 20cm apart; thinnings may be transplanted. Dry soil must be watered to ensure coolness and moisture, and for uniform germination.
SALAD MIX/BABY LEAF: Sow 50-100mm wide bands, 6 seeds/25mm. Cover seeds lightly, about 3mm. Firm soil gently, and keep surface moist until emergence in 3-5 days (or longer in cold weather). Harvest at 5-6 weeks.
NOTE: Radicchio grows best in cool or mild weather, i.e. autumn, winter, and spring. Summer crops can be successful if nights are cool (below 16°C).
DAYS TO MATURITY: From transplanting; add 14-21 days if direct seeding.
AVG. DIRECT SEEDING RATE: 1M/73m, 5M/365m, 10M/725m, 131M/acre at 3 seeds every 20cm in rows 45cm apart.
TRANSPLANTS: Avg. 500 plants/M (2 seeds per cell thinned to one seedling).
