Bok choy is a non-heading type of cabbage. Looking more like a white swiss chard, bok choy typically has very green leaves with succulent white midribs starting from a bulbous base. The Shanghai variety, commonly called baby bok choy, has green mid-ribs and leaf bases. It is probably native to China and eastern Asia.
Market information
Marketing. There is a good market for young or baby bok choy. Baby bok choy is light green in color. It is a staple in the Chinese community. To reach the non-Chinese community retail stores, it needs to be packed in smaller boxes, such as 10 pound boxes, rather than the standard WGA pack used in the Chinese groceries.
Wholesale market prices were reported for the San Francisco and Los Angeles markets for mature bok choy as follows (approximately 70 pound WGA crates):
San Francisco, 1987 Los Angeles, 1988
January-March $8.00-11.00 $12.00-28.00
April-September $9.00-12.00 $8.00-14.00
October-December $11.00-14.00 $10.00-14.00
Current production and yield. California leads the United States in total production of oriental vegetables. The major growing areas are cool season vegetable production areas such as the Salinas Valley, Santa Maria Valley and the Oceano-Arroyo Grande district. In California, bok choy is produced year round.
Use. Both the dark green leaves and the white ribs are eaten. Bok choy can be stir-fried or steamed or added to soups or other dishes. It is high in vitamin C, vitamin A, and it has fair amounts of calcium.
Culture
Climatic requirements. Average temperatures of 55°-70° F (13-21° C) are favorable. Temperatures above 75° F (24° C) may cause some burning of the tips and prolonged temperatures below 55° F (13° C) can cause premature bolting. Bok choy is also very sensitive to photoperiods for flowering. Long days (16 hour days for a month) induce flowering in some cultivars. Short days and warm temperatures keep the plant in the vegetative phase.
Propagation and care. Bok choy is a cool season crop and can be grown in the same regions and by the same methods used for other cole crops, particularly broccoli, cauliflower and cabbage. Bok choy is direct seeded 1/2 inch deep and 3 to 4 inches apart in rows 24 inches apart. It should later be thinned to 8 to 12 inches apart. It can be grown from transplants but special care must be taken to minimize the shock to prevent premature bolting. It requires a rich, well-drained, moist soil with a recommended pH of 5.5 to 7.0. Like all cabbages, bok choy should be encouraged to grow briskly. This is best accomplished with sufficient moisture and nitrogen. Apply at least one inch of water weekly.
Fertilization equivalent to 50-100 lb/acre of nitrogen, 50-75 lb/acre of phosphorus, and 50-75 lb/acre of potassium are recommended. About half the nitrogen should be applied at seeding and the other half shortly after thinning. During cool and wet weather, phosphorus deficiencies, particularly in heavier soils, will occur in bok choy. All the phosphorus and potassium should be applied before or at the time of planting.
Bok choy matures 40 to 60 days after sowing. Care must be taken when harvesting not to excessively crack the ribs. The heads are harvested by cutting the entire head off at ground level. They should be harvested before hard freezing weather occurs. After harvesting, the heads should be trimmed and all damaged or unsightly leaves and root remains removed.
Harvest and postharvest practices. USDA storage recommendations are 32°F (0°C) at 95 to 100 percent relative humidity, with an approximate storage life of 3 weeks. It is commonly shipped in wooden crates with 18 to 24 heads per container and wrapped in parafilm paper. Each container weighs approximately 50 to 60 pounds. The containers need to be properly cooled to avoid market losses due to decay.
Sources
W. Atlee Burpee & Co., 300 Park Avenue, Warmister, PA 18974.
Johnny's Selected Seeds, Foss Hill Rd., Albion, Maine 04910.
Park Seed Co., Cokesbury Road, Greenwood, SC 29647-0001.
Seeds Blum, Idaho City Stage, Boise, ID 83706.
Shepherd's Garden Seeds, Shipping Office, 30 Irene Street, Torrington, Conn. 06790.
Sunrise Enterprises, P. O. Box 10058, Elmwood, Conn. 06110-0058.
Tsang and Ma, P.O. Box 5644, Redwood City, CA 94063.
The Cook's Garden, P. O. Box 65, Londonderry, VT 05148.
Native Seeds, 2509 N. Campbell Avenue #325, Tuscon, AZ 85719.
More information:
Shephens, James. Minor Vegetables. Univ. of Florida Cooperative Extension Bulletin SP-40. June 1988, 123 pp.
Yamaguchi, Mas. World Vegetables. AVI Publishing Company, Inc. Westport, Conn. 1983. 415 pp.
The Packer. 1989 Produce Availability and Merchandising Guide.
Personal communication. Bill Fujimoto, Monterey Market, Berkeley.
Federal-State Market News Service. San Francisco Fresh Fruit and Vegetable Wholesale Market Prices 1987.
Federal-State Market News Service. Los Angeles Fresh Fruit and Vegetable Wholesale Market Prices 1988.
Tropical Products Transport Handbook. USDA Agric. Handbook 668. 1987.
Figure 1. Mature bok choy or pak choy. (Photo by Hunter Johnson).
Figure 2. Baby bok choy growing in the field. (Photo by Charlotte Glenn).
Reviewed by Keith Mayberry, Farm Advisor, Imperial County.
Reviewed by Pedro Ilic, 11/30/89.
Reviewed by Louie Valenzuela, 12/14/89.
3/19/90