- Chinese cabbage and bok choy are fall crops in Minnesota.
- Grow in well-drained yet moisture-retentive, fertile soil with pH of 6.0 to 7.5.
- Plant in an area where you have not grown cabbage, broccoli, cauliflower, turnips, rutabaga or Brussels sprouts in the last four years.
- Plant seed directly in the garden in July.
- Chinese cabbage and bok choy need to absorb water and nutrients steadily during their growth.
Chinese cabbage (Brassica rapa pekinensis), also called Napa cabbage, produces a tall, dense, barrel-shaped head of pale, thin, tender leaves. The leaves grow straight upwards and are more tender than round cabbage.
Bok choy, also called pak choi (Brassica rapa chinensis), grows an upright clump of dark green leaves, each with a very thick white or light green stalk.
Chinese cabbage and bok choy are now common in many Minnesota kitchens after growing in Asia for more than a thousand years. You can use them in stir-fries and soup, ferment them to make kimchi and mix them into fillings for egg rolls and dumplings. Although they are similar to common round cabbage, there are some important differences.
The only Chinese cabbage variety that grows well in Minnesota gardens is ‘Blues.’ The Minnesota Landscape Arboretum has also grown the ‘Rubicon’ successfully. There have been no trials for bok choy.
Soil pH and fertility
- Have your soil tested.
- Grow Chinese cabbage and bok choy in well-drained yet moisture-retentive, fertile soil with pH of 6.0 to 7.5. A good crop needs this ideal garden soil.
- It is not worth growing cabbage unless the plants absorb water and nutrients steadily during their growth.
- Improve your soil by adding well-rotted manure or compost in spring or fall. Do not use fresh manure as it may have harmful bacteria and may increase weed problems.
- Do not use any fertilizer containing a weed killer ("Weed and Feed"), as it may kill your vegetable plants.
- Plant seed directly in the garden in July. Chinese cabbage takes about two months to mature, so an early July planting will be ready to harvest before a hard freeze.
- Bok choy is quicker to mature and you can harvest it before head formation. A late July planting will be ready before cold weather.
- Plant seed shallowly, one-fourth to one-half inch deep. Plant three seeds every 12 inches for dwarf varieties, or every 18 inches for full-sized heads.
- Keep the soil moist during seedling emergence.
- After the seedlings emerge, thin to one plant every 12 to 18 inches.
- Take good care of the seedlings, as they experience extreme heat, wind, drought and insects when they are most vulnerable. Water them as needed.
A row cover will protect the plants from insects, wind and cold during the first weeks of growth. Use a lightweight material so that temperatures do not get too hot under the cover.
If strong winds loosen a floating row cover, it can do more damage than the plants would suffer without it. Anchor it firmly with soil and/or pins at the edges. You can also support the row cover with wire hoops to form a low tunnel.
Chinese cabbage and bok choy are fall crops in Minnesota. The cooler daytime temperatures of May and early June are ideal for these plants, but Minnesota spring weather is unpredictable.
If the plants experience late spring frosts, or more than a week of nights below 50°F, they are likely to bolt (produce a flowering stalk and stop growing) once warm weather returns.
If you delay planting until after the last frost to avoid the risk of bolting, the plants will have to mature in hot weather. Although some varieties are tolerant of heat, hot days during the formation of the head lead to narrower leaves and less dense heads.
Plant in mid-summer, so that the plants will mature in the shortening days and cooler temperatures of September.
How to keep your Chinese cabbage and bok choy healthy and productive
- Asian cabbages need good soil moisture. The best quality heads are firm, crisp, juicy, sweet and sometimes peppery, but without bitterness.
- If the plants do not receive consistent rainfall or irrigation, they will have poor texture and too much bitterness. Outer leaves may brown and dry up, or the plant may not form a head.
- Chinese cabbage is vulnerable to tipburn of the leaves. This is due to uneven soil moisture levels, leading to poor calcium uptake.
- Water your cabbage planting during dry spells.
- One inch of rainfall per week is good.
- If your soil is sandy, water more often than once a week.
- An inch of water will wet a sandy soil to a depth of 10 inches, a heavy clay soil to 6 inches.
- Use a trowel to see how far down the soil is wet. If it is only an inch or two, keep the water running.
- Frequent, shallow cultivation with a hoe or other tool will kill weeds before they become a problem.
- Hoe just deeply enough to cut the weeds off below the surface of the soil. Do not damage the plants when cultivating.
- Mulching with herbicide-free grass clippings, weed-free straw, or other organic material to a depth of three to four inches can help prevent weed growth, reducing the need for frequent cultivation.
There are several common insect pests of Chinese cabbage and bok choy.
- Flea beetles chew small holes in leaves. Seedlings are most vulnerable to injury.
- Imported cabbageworm, cabbage looper, and diamondback moth larvae feed on the leaves. Young seedlings and transplants are most vulnerable to injury.
- Cabbage maggots feed on the roots and injuring the plants, sometimes killing them.
- Several diseases affect plants in this family, including alternaria leaf spot, black rot, black leg and clubroot.
- Many diseases come on infected seed.
- Always purchase clean, disease-free seed from a reliable source.
- Remove diseased plant material from the garden and destroy it, or bury it where found.
- Use good cultural control practices to reduce disease problems to a manageable level and have a successful harvest.
Practice crop rotation.
- Avoid planting Chinese cabbage or bok choy where you have grown related crops (broccoli, cabbage, cauliflower, Brussels sprouts, turnip, rutabaga, collards, mustard, kohlrabi) in the previous three years.
- Diseases of this plant family can remain in the soil and infect each year’s crop.
For help in diagnosing unknown problems, visit What’s wrong with my plant?
- Harvest Chinese cabbage when the heads reach a usable size.
- The heads should feel firm and dense when pressed. If they feel loose, they may need more time for the inner leaves to grow.
- To harvest, cut the head off above the outer leaves.
- Chinese cabbage is not able to stand in the garden once mature, as does common round cabbage. Harvest promptly. Otherwise, the plants may bolt, and quality will be lost.
- Chinese cabbage will tolerate below-freezing temperatures late in plant development, although they are not as cold-hardy as round-head cabbage.
- If overnight lows below 30°F are in the forecast, you can protect the heads with a row cover.
- You can harvest bok choy a few leaves at a time rather than waiting for the whole head to mature.
- Pick the oldest, largest leaves from the outside of the plant. Younger leaves will continue to grow for later harvest.
- Most gardeners wait for the head to reach its mature size. For dwarf varieties, this may be only six inches tall. Full-sized varieties can be a foot tall.
- Cut the head while the oldest leaves are still tender. Bok choy will not hold its quality if left in the garden a long time.
- If bok choy plants begin to bolt, the leaves will not grow any more. Harvest the whole plant before the flowers open, and use the flower stalk as you would broccoli.
Storage and kimchi
Bok choy is not good for long storage, so you should use it soon after harvest. It may last a week or two in the refrigerator.
You can store Chinese cabbage for weeks or months, but only in cold, moist conditions of 32°F to 40°F and 95% humidity. These conditions are colder and much moister than a refrigerator, and difficult for most home gardeners to create. If you want to store Chinese cabbage, you will need a root cellar.
A time-honored means of preserving the cabbage harvest is fermentation. The European version is sauerkraut, and you can use Chinese cabbage just as you would round cabbage to make kraut. It will be tenderer and less crisp than standard sauerkraut. You can freeze sauerkraut, or can it in a boiling water bath.
The traditional Korean method of fermenting cabbage is kimchi.
Both sauerkraut and kimchi will keep for weeks in the refrigerator.
Reviewed in 2018