In the first season of growth the biennial plant produces a rosette of leaves on a thick fleshy root. This requires 4 to 7 months of field growth. The production of high quality roots is the skillful part of witloof production. At harvest the roots are lifted from the soil and cooled. They are then "forced" in pits or cold frames. This second or forced growth period produces a compact apical bud which left unharvested would develop into the seed stalk.

Market information

Current Production and yield. The forced crop is harvested as early as late September and can continue through May with the peak period during November through March.

Use. The Belgian endive is an important European vegetable. It has a delicate, somewhat bitter flavor and is used cooked in a variety of dishes and raw in salads. The edible product is the blanched cluster of leaves often yellow tipped from the compact bud, which is usually called the head or chicon.

Nutrition. High in fiber, iron and potassium.

Culture

Climatic requirements. The initial field phase of production benefits from uniformly cool temperatures of mild days (70°F) and cooler nights (45°F). During forcing procedures, temperatures are critical, with a preference for slightly warmer conditions (60°-70° F) in the root area versus the tops. The temperature around the developing heads should be about 5° F lower than root temperatures.

Propagation and care. The production of high quality uniform roots is the skillful part of witloof production. The crop is usually started from seed and grown similarly to lettuce. However, plant spacings are closer, 4 to 5 inches apart in the row with rows 18 to 20 inches apart; equivalent to about 100,000 plants per acre. Growth resembles romaine lettuce and is grown for 3 to 4 months before the roots are dug. Prior to digging, the foliage is mowed but care must be taken to leave the growing point at the apex of the root undamaged. It is from this tissue that the head (chicon) will develop. Roots need to be carefully handled during digging and cold storage. Cold storage, whether it occurs in the field or in cold storage rooms, is needed to vernalize the tissue. Without proper vernalization, forcing at raised temperatures will be erratic. Storage temperatures should be 32° F.

Forcing consists of placing the roots upright one against the other in soil pits or coldframe like structures under a cover of soil. Varieties that remain compact without a soil cover have been developed. This now allows most forcing to be done using hydroponic techniques. The roots can be placed in trays rather than soil. Both circulating and non-circulating solutions are used to supply moisture and warmth to the roots. After 20 to 30 days the heads are ready to harvest.

Harvest and postharvest practices. The heads are snapped from the roots by hand, then trimmed and packed. USDA storage recommendations are 36° to 38°F (2° to 3°C) at 95 to 98 percent relative humidity, with an approximate storage life of 2 to 4 weeks.

Sources

Figure 1. Belgian endive shown in cold frames in its second or forced growth period. (Photo from Vince Rubatzky).

Figure 2. A closer view of the chicons, or Belgian endive heads, placed side-by-side in a coldframe. (Photo from Vince Rubatzky).

Reviewed by Vince Rubatzky, 12/19/89

Reviewed by Keith Mayberry, 9/89

5/1/90