Cultivars for forcing are sown in May and June; non-forcing varieties in June and July. For 'mini leaves', non-forcing types can be sown at any time in a glasshouse from late winter until early autumn.
Sow thinly 13mm (0.5in) deep in rows 30cm (12in) apart; for mini leaves every 5cm (2in).
Chicory prefers an open, sunny site but summer crops and mini leaves will tolerate some shade, soil should be fertile and free draining.
Thin seedlings of forcing types to 15cm (6in) apart, thin non-forcing ones to 30cm (12in), and 5cm for mini leaves.
Water thoroughly in dry weather and give plants in containers a general liquid feed fortnightly in summer.
Lift the roots of ‘forcing’ varieties in November, discard any less than 2.5cm (1in) across at the crown. Cut back leaves to 2.5cm (1in) above the crown.
Pack roots horizontally in sand in a cool shed until required. Force a few at a time by planting five in a 25cm (10in) pot of moist compost, leaving the crown exposed.
Cover with a black polythene bag (or pot with drainage holes covered to exclude the light) and keep at 10-15C (50-59F) to produce the ‘chicons’.
Start blanching radicchio about 12 weeks after sowing. Make sure the leaves are dry, and loosely tie together. Cover with a black plastic pot with the drainage holes covered until the leaves blanch. Most types form good heads without any need to tie or blanch – the outer leaves blanch the inner ones.
Non-forcing types: cut heads from late summer until October; protect plants overwintered outdoors with cloches or fleece.
Forcing: ‘chicons’ are ready to harvest when 15cm (6in) high, after around four weeks.
There are three types of chicory: ‘forcing’ types like ‘Whitloof’ grown for their plump leafy heads or ‘chicons’ when blanched; Red Chicory, or radicchio, which responds to change in day length by turning red; and non-forcing or sugar-loaf types which produce large hearted lettuce-like heads for autumn harvest.
‘Indigo’ AGM: Dense round heads, uniform with dark green outer leaves and red hearts
‘Palla Rossa’ AGM: Medium to large heads; well-filled red hearts; fairly uniform. Does not bolt
‘Pan di Zucchero’ AGM: Uniform medium to large plants with dark green outer leaves. Hearts blanch well
‘Zuckerhut’ AGM: Medium-sized plants with dark green outer leaves and well developed, well-blanched hearts
Forcing or Witloof types
‘Witloof de Brussels’: one of the most famous forcing types
Rotting: leaves rot in damp conditions or when plants are grown under cover.
Remedy: remove damaged leaves, and improve ventilation under cover.