Last revised February 10, 2010
(See also file on Radicchio)
The terms "chicory" and "endive" are frequently interchanged because the "forced" product of Witloof chicory has been erroneously named French or Belgian endive. This information deals with the production of the forced Witloof chicory for chicons (4-6 inch, spindle-shaped heads or buds). Other synonyms are White Endive and Dutch chicory.
Another type of chicory, whose dried roots are used as a coffee substitute, is Magdeburgh or Italian Dandelion. Tops may also be used in cooking like spinach. The field production phase of both these types may be handled similarly.
Recently, chicory root is being considered as a natural source of fructose oligosaccharide, a zero-calorie sweetener. Washington State University information indicates that the Pacific northwest regions west of the Cascade Mountains may be ideally suited for its production.
Witloof chicory growing in Alkmaar, Holland. Photo credit: Bill Mansour, Oregon State University
Variety results from Connecticut indicate the following:
Early to mid winter forcing: Zoom.
Late (forcing through March): Flash.
Witloof chicory must be planted in friable soils, that would otherwise be suitable for carrot production. The use of raised beds greatly improves root quality for forcing.
Loose fertile loams, and muck soils are best. Soils should provide good water holding capacity and good internal drainage, and a pH of 6.5 and above. Since roots of Witloof are harvested in the fall, soils should be chosen that allow harvest in moderately rainy conditions.
Witloof seed numbers approximately 25,000 per ounce. Use a fungicide treated seed whenever possible. Have germination checked before planting if germination value is not known or current.
Pelletizing seed allows precision planting. Plant as shallow as possible, commensurate with soil and moisture conditions. One and a half to 2.5 lb of raw seed are required per acre. With graded and pelletized seed, 250,000 pellets are used per acre. These are thinned to the spacings indicated below.
Witloof performs best under cool temperatures and requires 110 to 130 frost free days in order to produce roots of desirable size for forcing.
Witloof varieties are planted beginning in April, ending in May. March plantings would need to be covered with plastic to prevent premature bolting (seed stalk development). These are dug from August through October for forcing.
Witloof is planted at spacings of 4-6 inches in the row with rows 18-24 inches apart. This produces populations of from 30,000 to 80,000 plants per acre. Select spacings and row arrangements that allow use of small carrot or potato diggers for harvesting roots for forcing. Uniformity of spacing is important since this influences the size of chicons produced.
For the most current advice, see Nutrient Management for Sustainable Vegetable Cropping Systems in Western Oregon, available as a free download from the OSU Extension Catalog
Nitrogen: Do not use more than 50 lb N per acre. Excessive nitrogen produces heavier tops at the expense of good roots.
Phosphorus: 100-150 (P2O5) lb/acre - apply all at time of seeding or transplanting preferably banded 2 inches to the side and 2 inches below the seed or plant roots.
Potassium: 50-150 (K2O) lb/acre - broadcast prior to planting.
Sulfur: 20-30 (S) lb/acre - broadcast prior to planting.
These recommendations are intended to provide adequate fertilizer. Nitrogen rates especially may need to be adjusted depending on crop, planting date, weather conditions and soil type.
These crops require a uniform supply of water for tender growth. Frequent irrigations are preferred because these crops are shallow rooted. A total of 12-14 inches of water may be necessary depending on seasonal variation, variety and planting date.
Soil type does not affect the amount of total water needed, but does dictate frequency of water application. Lighter soils need more frequent water applications, but less water applied per application.
Witloof chicory is harvested from the field after about 130-150 days, when roots are of adequate size. Roots may be dug for forcing from September through November. Do not harvest after the end of November because vernalization may have occurred and may result in bolting.
Maturity of roots can be judged by examining a vertical section cut through the crown. When a white section about the size of a fingernail (1/4 to 3/8 inch thick) is present just below the crown section, the root is ready for harvest and forcing. When this white tissue is less than 1/4 inch thick, the roots are immature and will not produce tight chicons. When larger than 3/8 inch, numerous, mostly unmarketable chicons may form. Roots should be 1 1/4 to 2 1/2 inches in diameter. Harvest as follows:
1. Undercut and loosen roots with a bar blade, and allow roots to cure in the field for 3 or 4 days. Do not allow roots to be exposed to sunlight.
2. Cut tops 0.5 to 1 inch above the shoulders of the roots. Remove as much of the top as possible without injuring the growing point. Failure to remove enough of the tops can result in decay during forcing. Tops may mechanically removed just prior to undercutting if this can be done without damage to the growing point.
3. After loosening roots, roots may be hand harvested, or dug with potato equipment or carrot equipment after the tops are removed.
4. Sort roots by diameter. Roots about l l/2 to 2 1/2" in diameter are ideal.
Roots are cut to a length of 6-9 inches and packed upright, tightly, in bins that are about 12 to 15 inches deep, with soil or a hydroponic solution. Both circulating and non-circulating hydroponic systems are used. Roots are forced in darkness in cellars or forcing rooms. A temperature of 32-34 F is used for holding and 50-60 F temperature is used for forcing. Ideally, air temperature should be 5 F cooler than the root temperature during forcing. To accomplish this, some forcing rooms are designed with hydroponic trays into which the roots are placed and through which water at a temperature of 60-70 degrees is circulated. Air temperature is maintained at 55-65 F using appropriate refrigeration equipment. Hydroponic trays are usually stacked in frames, allowing the necessary space between trays for harvest.
Forcing rooms should be kept at 90% or more relative humidity. At the proper temperature 3-4 weeks are necessary for proper chicon development.
Chicons are cut or snapped from the roots and any loose outer leaves removed. They should be 4-6 inches in length, compact and spindle-shaped. Chicons 2-3 ounces each, and free of green color, are most desirable. They must be handled carefully to avoid abrasion and mechanical damage. From each 100 lb of roots being forced, about 15-20 lb of Witloof chicons may be expected.
Vernalization temperatures prior to forcing affect chicon quality (sugars and shape), with greater vernalization producing longer chicons.
Cool product as quickly as possible. Witloof should not be wetted. Store cartons in a cold, room at 34-36 F and 95-98% relative humidity.
This bullet-shaped salad vegetable should keep 2 to 4 weeks at 34 to 36 F with high relative humidity. Compact chicons 4 to 5 inches in length are most desired. This vegetable is mainly imported by air from Europe. Over-wrapping with perforated plastic film is beneficial. In marketing, blue paraffin paper may be used for protection against light and moisture loss. Leaves should be white with slightly yellow tips.
Deterioration shows as marginal leaf browning after 2 to 4 weeks at 36 F, 1 to 2 weeks at 40 F, and 1 week at 60 F. Holding witloof chicory in 3 to 4 % oxygen with 4 to 5 % carbon dioxide at 32 F about doubles its useful life compared to storage in air. This controlled atmosphere delays greening of the tips of the leaves in light and opening of the chicons.
All these crops are packaged in cartons containing 10-20 lb, depending on the item. Consult buyers for preferred packaging, and container sizes. Package Witloof chicons in cartons lined with blue moisture proof paper to exclude light and retain moisture.