Chicory

Chicory is native to Europe, central Russia and western Asia, and it has spread widely across North America. People have grown it for its edible leaves, buds and roots for centuries. Plants typically grow 2 to 4 feet (61 to 122 cm) tall. Its blue flowers usually close by midday.

Wild chicory has bitter leaves, and older leaves are cooked to reduce the bitterness. Cultivated types such as witloof (Belgian endive) and radicchio look and grow very differently from the wild plant.

Sowing. Sow chicory seed about ¼ inch (6 mm) deep in early spring. Seeds germinate best at 65 to 70 °F (18 to 21 °C), and temperatures above 80 °F (27 °C) slow germination. A commercial seed supplier advises ¼ to ½ inch (0.6 to 1.3 cm) deep and keeping the soil from drying out during germination.

When to sow. Witloof and radicchio can both be seeded 3 to 4 weeks before the last frost-free date for the growing area.

Site and soil. Chicory grows best in full sun and in fertile, well-drained soil rich in organic matter.

Thinning and spacing. Thin seedlings when they have 3 to 4 true leaves. Space witloof 9 inches (23 cm) apart in rows 20 inches (51 cm) apart, and radicchio 8 inches (20 cm) apart in rows 12 inches (30 cm) apart. For radicchio, sow several seeds per spot because not every seed germinates.

Types. Witloof is grown for its root, and radicchio is grown for its head of leaves. Witloof varieties named include Daliva, Flash and Zoom, and radicchio varieties include Rossa di Treviso and Firebird.

Watering. Water regularly to keep the soil evenly moist, about 1 to 2 inches (2.5 to 5 cm) per week. Organic mulch such as straw or grass clippings helps conserve moisture, cool the soil and control weeds.

Feeding. Apply about ¼ cup of a 21-0-0 nitrogen fertilizer per 10 feet (3 m) of row, 4 weeks after transplanting or thinning. Avoid extra nitrogen once heads begin to form.

Weeds. Chicory does not compete well with weeds, so control them early and cultivate shallowly to avoid root damage.

Pests. Slugs, snails and cutworms are occasional pests. Aphids make leaves crinkle and curl, and worms and loopers chew holes; insecticidal soap or a strong water spray can dislodge them.

Diseases. Root rots can cause wilting during forcing, and good air movement reduces them. Viruses spread by aphids cause stunted growth and yellowing between leaf veins, so controlling aphids helps.

Bitter leaves. High summer heat reduces quality and can cause bitter flavors, and drought stress also makes leaves bitter.

Spreading. Chicory is considered invasive in some states. Its seeds spread readily, so take care not to let grown plants self-seed and escape.

Leaves. Harvest witloof leaves while they are young and tender. Harvest radicchio when the leaves or head reach full size, cutting the stem just below the leaves to keep the head together; delayed harvest makes it bitter and tough.

Roots and chicons. Dig witloof roots just before the first frost date, cut the leaves about 1 inch (2.5 cm) above the crown, and trim the roots to a uniform size. To force chicons, keep the roots in complete darkness in a cool cellar at 50 to 60 °F (10 to 16 °C); chicons are ready 3 to 5 weeks later.

Roots. Trimmed witloof roots can be stored for 3 to 7 weeks at 32 to 34 °F (0 to 1 °C) before forcing. A commercial seed supplier suggests storing roots like carrots at 32 °F (0 °C).

Radicchio and chicons. Radicchio keeps 2 to 3 weeks at 32 °F (0 °C) and 95% relative humidity, and chicons keep 2 to 4 weeks under the same conditions. Keep radicchio away from apples and pears, which make it bitter.