The Brassica family is thought to have originated in the eastern Mediterranean and Asia Minor. Selective breeding in China and Japan has resulted in many different varieties. Pak Choi grows from a rosette of flattened white stems topped by green leaves.
This nutritious and fast growing green leafy vegetable is popular in Asian stir-fries and in other dishes calling for cooked or fresh greens.
Elevation: Pak Choi is a cool season annual and can be grown in the tropics between about 500 and 1,500 meters (1500-3200 ft).
Rainfall: Plants require good soil moisture preferably by drip irrigation and benefit from mulching.
Soil Types: It prefers a soil pH of between 6.0 and 7.5 and soil that is rich in minerals. Well-rotted organic matter dug into the soil before seeding and during the growing season is beneficial.
Temperature range: Between 16-22° C (60-73º F) with a diurnal variation of 5-6º is desirable.
Harvesting and Seed Production
Pak Choi should be planted at the beginning of the winter season so that it matures during cool weather. Seeds can be direct seeded or started indoors and moved into the garden as early as possible. Pak Choi plants are usually harvested whole after only 40 days by cutting just above the soil line. Separate plants intended for seed production as varieties will cross-pollinate. Sun dried seeds will remain viable for up to four years if kept in a dry and cool place.
Pests and Diseases
Rotate crops of Brassicas as soil will harbor micro-organisms that can re-infect each year’s crop. The larvae (caterpillars) of many insects will chew holes in the leaves and leave webs and droppings to rot the plant. Pick off caterpillars, use row covers, pheromone lures, interplant with repellant strong-smelling plants such as sweet basil, alliums or marigolds or use a neem-based spray or a microbial spray such as Bacillus thuringiensis (BT). Club root in highland areas can be avoided by a 5 year rotation schedule.
Cooking and Nutrition
Pak Choi has a mustard-like flavor and is rich in vitamins A, C and calcium. The leaves and stems can be boiled, sautéed, steamed, stir fried, eaten raw in salads or pickled. In China, the coarser leaves are dipped in boiling water and hung out to dry in the sun for several days then stored for the winter months.