Whether growing from seeds or nursery seedlings, this vegetable is fast-growing and planted in early spring for a spring-to-early-summer harvest, or in late summer and early fall for a mid- to late-fall harvest. You can succession plant every couple of weeks for a longer harvest period. 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 temperatures below 50 degrees 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. You may have better luck avoiding bolting if you plant bok choy in the late summer and early fall when temperatures are fairly steady.
Selecting a Planting Site
The planting site must have well-draining rich, fertile soil where rain can saturate the ground. The site should have full sun for most of the day, especially if it’s a fall crop. A spring crop, which is trickier due to the plant’s tendency to bolt because of temperature changes, should have three to five hours of full sun and partial shade, especially in the afternoon. Container growth is also possible for a small garden of bok choy.
Spacing, Depth, and Support
Seeds should be planted 1/2 inch apart about 1/4 inch deep. If planting seedlings, space them in the ground 6 to 12 inches apart for adequate growth. When growing multiple rows of bok choy, space the rows about 18 inches to 30 inches apart for best growth. If you are growing more than one row of bok choy, make sure your rows are 18 to 30 inches apart. If you would like a continuous harvest of bok choy, add in new plants every two weeks. No support system is necessary for bok choy.
Bok Choy Care
Light
Bok choy grows best in full sun, but it tolerates part shade, especially necessary in the summer months. It typically needs about six hours of direct sun each day.
Soil
You’ll need well-draining soil enriched with organic matter. 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 fairly moist but never soggy soil conditions. Drought can cause it to bolt to seed too early. Your plants will need consistent watering, especially in the drier fall months. The best rule of thumb is to give bok choy 1 inch of water a week so the soil remains moist between waterings.
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 when there are mild winters. However, it may 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 organic feeding should be done at the time of planting. Chemical fertilizers should not be used during its growth period.
Types of Bok Choy
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 baby bok choy leaves 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.
Bok Choy vs. Napa Cabbage
Bok choy and napa cabbage are both types of Chinese cabbage and are often confused with one another. The two vegetables look alike, each having fibrous, long, coarse green leaves. Bok choy is more flavorful (and on the bitter side) than napa cabbage. But napa cabbage is crispier and grows larger than bok choy.
Harvesting Bok Choy
Depending on the variety and the weather, bok choy should be ready to harvest in 45 to 60 days after seed germination. Harvest leaves from the outer part of the plant to allow the inner leaves to continue growing. When you’ve harvested what seems like all the leaves from plants, slice the plants off about 1 inch above the ground and they should re-sprout for you, or you can propagate in water. The re-sprouted plants will be smaller, but still delicious. The young, tender seedlings culled out during thinning can be added to salads or added to stir-fry dishes.
How to Grow Bok Choy in Pots
Growing bok choy in pots is feasible if you don’t want to plant rows of it outdoors or you need to place the plant in a spot with sun, but may not have the best soil conditions. You will need large containers of any material and with ample drainage holes. A pot should measure at least 12 inches wide and 20 inches deep for one plant and double the size for more plants. Fill the pot with a lightweight potting mix that is well-draining, but do not use regular dense soil. A good potting mix can be a mixture of peat, compost, and hopped bark that drains well. Place the pot in a spot where it will receive a minimum of 6 hours of sun. Water the container regularly without letting the soil become dry to the touch. Water as close to the soil as possible without letting moisture hit the leaves.
Propagating Bok Choy
Propagating bok choy is a great way to make the plant’s scraps useful, then you can toss the rest into the compost bin. The easiest way to propagate bok choy is to soak scraps in a jar or bowl of water. Here’s how to propagate bok choy in water.
How to Grow Bok Choy From Seed
If sowing directly into the garden, begin planting a week 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, make sure to harden them off before planting. Hold off transplanting them until nighttime temperatures remain above 50 degrees, or be prepared to cover them with garden cloth. 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 6-inch spacing.
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. Slugs, whiteflies, and aphids can also harm the leaves. Row covers or garden fabric for outdoor plants will help to minimize damage from all of these pests. Cover potted bok choy with netting to protect it from insects.
