Chinese cabbage, scientific name Brassica rapa subspecies chinensis and pekinensis, refers to two different varieties of Chinese vegetables commonly used in Chinese cuisines. Such green leafy vegetables are related to the commonly known western cabbage and are of the same species as the turnip.
The foliage is usually light to medium green with white veins, plants reach a height of 1 to 2 feet (30 – 60 cm), with a spread of 12 to 18 inches (30 – 45 cm). Stalks are usually white.
Chinese cabbage by naturalflow (CC: https://www.flickr.com/photos/vizpix/)
The most common variant is known as the Napa cabbage, pac choy, or bok choy. Chinese cabbage is actually a cold-weather vegetable that is best grown in cool temperatures during a long growing season of 50 to 85 days.
For best results it is best planted near coastal locations as the sea breeze helps in making the plant cool.
For cold regions, seeds should be sown four to six weeks before the last frost ready to be harvested before the outside temperature reaches above 75°F (24°C). For the more common western species, see this article on how to grow cabbage plants.
Chinese cabbage has broad, thick, tender leaves with heavy midribs. It is a hardy biennial grown as an annual plant. Several varieties are available; some are tight headed while others are loose headed. Plants can grow from 15 to 18 inches (38 – 45 cm) tall.
In colder regions Chinese cabbage can be grown in an open site that has full sun. The soil should be moisture retentive, well-drained, and slightly acidic - with a minimum pH of 5.4. Lime can be added to adjust soil pH level.
Since brassicas have high requirement for nitrogen while needing very firm soil, it is best to apply or top dress with a liquid feed such as seaweed fertilizer during growth to ensure sufficient nutrient levels.
For warmer regions, Chinese cabbage should be planted in partial shade and in a soil that is rich in organic matter. Aged compost should be added to the planting beds a couple of weeks before planting and side dress crops with compost again during mid-season.
It is vital to have a minimum of three year rotation plan because brassicas are prone to various soil infections such as club root.
Grow Chinese cabbage in autumn or spring when temperatures range from 45 to 75°F (7 – 24°C). It is usually easiest to grow in the autumn.
As a cool weather plant, this green leafy vegetable will bolt and go to seed quickly in warm weather and long days. Therefore, seeds should be sown four to six weeks before the average date of the last frost. Directly sow the seeds in the garden, as transplanting seedlings can result in seed bolting. For mild winter regions, Chinese cabbage can be planted in late summer or early autumn for harvest in late autumn.
Chinese cabbage seedlings by stereogab (CC: https://www.flickr.com/photos/stereogab/)
Sow seeds (up to four years old) at a depth of ½ inch (1.25 cm) and four inches (10 cm) apart; thin seedlings from 12 to 18 inches (30 – 45 cm) apart. Space rows approximately 18 to 30 inches (45 – 60 cm) apart, depending upon variety.
Germination occurs at 50 to 80°F (10 – 26°C) and seedlings are expected to emerge in four days to two weeks. As noted above it is not ideal to transplant Chinese cabbage. When seedlings are started indoors then they should be planted in biodegradable paper pots or peat, which can be easily set into the garden.
To prevent bolting do not sow out seeds before the nighttime temperature can still drop to 50°F (10°C).
The soil should be evenly moist to promote faster growth and enhance tenderness. Slow growth can result to brittle crops and in plants going to seed.
Careful Chinese cabbage care is required whenever seasonal weather is warm, always keep the plants cool – do not let them sit in direct sun for more than eight hours per day.
Spread small amounts of fertilizer around the garden bed a month after planting and water in immediately. Once the cabbage head starts to be visible, apply a light dressing of urea to give them an extra growing boost.
Chinese cabbage is mostly attacked by aphids, cabbage worms, cabbage root maggot, cut worms, and flea beetles. Aphids can be hand-picked or hosed off (also encourage natural enemies of aphids such as beetles. Spraying thuringiensis can help control cabbage worms. Minor pests include Cabbage loopers, Nematodes, and slugs.
The plant is susceptible to clubroot (increase soil pH by adding lime), black rot, purple blotch, Black leg, and yellow virus. It is best to plant disease resistant varieties and destroy any infected plants immediately. Avoid handling plants when wet to prevent the growth of certain infections.
When the plant is already compact and firm, cut the whole heads at soil level before seed stalks form; this is normally 50 to 80 days after sowing. The harvest should be completed before the weather freezes. Chinese cabbage can still be harvested for greens if the first fall frost arrives before the forming of heads.
As with other green leafy vegetables, Chinese cabbage is best kept in the refrigerator’s vegetable compartment. Wrap it first in newspaper, this will allow it to be stored for about four weeks. It can also be frozen and blanched; this will allow a longer storage of three to four months.