Bok Choy Plant Profile

Bok Choy

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Bok choy, also known as Chinese cabbage, is a cool-season biennial vegetable that is normally harvested for consumption in its first year of growth. It has crisp stalks surrounded by smooth, tender leaves with a flavor that is somewhere between cabbage and chard. Plants form an upright head, with outward flaring leaves, and its white or green stalks look like smooth, non-stringy celery. The stalk can shoot up to twice the size of the plant. Flower stalks grow from the center of the plant and have the yellow, four-petal cross typical of the cruciferous family.

Bok choy is a type of Chinese cabbage that once was limited to meals in Chinese restaurants. These days, however, you are just as likely to find it growing in backyard gardens. There are a surprising number of varieties to try. Its Chinese name, "pak choi," translates to "white cabbage," probably because of its blanched centers, but there are green varieties too. Plant size varies depending on variety— some are less than 10 inches tall, but standard varieties grow 1 to 2 feet tall, with a spread of about 12 inches.

Whether growing from seeds or nursery seedlings, this vegetable is generally planted in early spring for a spring-to-early-summer harvest, or in mid- to late summer for a fall harvest. You can succession plant every couple of weeks for a longer harvest period.

Botanical Name Brassica rapa var. chinensis
Common Name Bok choy, Chinese cabbage, pak choi, bok choi
Plant Type Biennial vegetable (usually grown as annual)
Size 6 to 24 inches; 6- to 18-inch spread
Sun Exposure Full sun, part shade
Soil Type Rich, well-drained
Soil pH 6.5 to 7.0 (slightly acid to neutral)
Hardiness Zones 2 to 11 (USDA); grown as an annual
Native Area China
Toxicity Non-toxic

How to Plant Bok Choy

Bok choy is a fairly fast-growing vegetable that is usually planted from seeds, either directly into the garden immediately after danger of frost has passed, or indoors about four weeks before the last frost. You can also buy nursery seedlings to plant in the garden after frost danger has passed.

Planting Tip

It can take some practice to learn when bok choy should be planted in order to avoid setting seed in its first season. This vegetable will bolt (send up flower stalks) if the weather is too warm, but paradoxically it can also bolt if exposed to frost when it is young. In areas with cool springs that quickly shift to warm temps, it may be best to start seeds indoors then transplant the seedlings outdoors when all danger of frost has passed.

Plant Care

Light

Bok choy can handle full sun, but it grows best in part shade. It needs about 3 to 5 hours of sun each day.

Soil

You'll need well-draining soil with a lot of rich, organic matter mixed in. Bok choy will grow in a soil pH from 6.0 to 7.5, although something in the 6.5 to 7.0 range is best.

Water

Bok choy needs consistent watering, especially in the fall. Drought can cause it to bolt to seed.

Temperature and Humidity

Bok choy grows as an annual in every hardiness zone in the U.S. It does best in cooler weather; dry and hot conditions can cause bok choy to bolt prematurely. This vegetable is not as winter hardy as smaller leaved Asian greens, but it may be winter-hardy under cover in USDA Hardiness Zones 4 to 7. However, it will quickly bolt to seed the following spring.

Fertilizer

Add compost and organic fertilizer to the soil when planting bok choy. These plants are heavy feeders, preferring soil that is rich in potassium, nitrogen, and phosphorus. But feeding should be done with organic at the time of planting, not using chemical fertilizers during its growing period.

Bok Choy Varieties

Although there are dozens of varieties of bok choy, many times you will find seed packets with no variety name. The small "baby" bok choys are popular in China and becoming more widely available elsewhere. You'll need more of them for a recipe, but they grow and mature very quickly.

  • 'Black Summer' has very dark leaves. It is planted in fall and harvested in late fall or winter.
  • 'Ching-Chiang' is a quick-growing dwarf that can handle early spring weather/
  • 'Joi Choi' is a medium-sized plant with good bolt resistance.
  • 'Mei Qing Choi': is a dwarf variety that grows quickly (35 days).
  • 'Win-Win' is a cultivar with extra-large, dense heads; it is slow to bolt.

Harvesting

Depending on the variety and the weather, bok choy should be ready to harvest in 45 to 60 days after seed germination. Slice the plants off about 1 inch above the ground and they should re-sprout for you. The resprouted plants will be smaller, but still delicious.

Bok choy is found in most grocery stores, and its uses go far beyond the usual stir fry. The tender young leaves can be eaten raw in salads or sandwiches. You can swap it for celery sticks, toss it in soups and stews, and even grill it. Bok choy can also be substituted for other cabbages

Is Bok Choy Toxic?

When eaten cooked, bok choy is packed with essential nutrients. However, eating too much raw bok choy may cause thyroid problems, due to an enzyme found in the vegetable. This enzyme is deactivated by cooking.

How to Grow Bok Choy From Seed

If sowing directly into the garden, begin planting one to two weeks before your last frost date. Seeds are quick to germinate, usually within four to eight days. You can also start seed indoors about four to five weeks before your last frost date. If you've started the seeds indoors, hold off transplanting them until nighttime temperatures remain above 50 degrees, or be prepared to cover them. If the seedlings are exposed to frost or prolonged cold temperatures, they will think they've been through a winter and start to bolt.

Plant seeds 1/2 inch deep, spaced 1 inch apart. Thin and eat the plants when they are a couple of inches tall. If you are growing full-sized plants, thin to at least a six-inch spacing.

Tip

The young, tender seedlings culled out during thinning can be added to salads or added to stir-fry dishes.

Common Pests and Diseases

Bok choy is not usually affected by the most common brassica diseases. It is, however, attractive to many insect pests, including cabbage loopers and cabbage worms. Flea beetles can riddle the leaves. Row covers will help to minimize damage from all of these. Slugs, whiteflies, and aphids can also harm the leaves.