Vegetable · Brassicaceae
Bok Choy
Brassica rapa subsp. chinensis
Sown in cool weather and kept evenly moist, bok choy swells into crisp stalks and broad leaves that crowd a bed within six weeks.
Full sun
Every 2–4 days
50–77°F · 10–25°C
40–55 days
Overview
Bok choy is a cabbage-family plant grown for its thick, juicy stalks and the broad, spoon-shaped leaves that flare from them, not for a packed head. Those stalks and leaves swell quickly, building a full plant in 40 to 60 days, so the plant fills a bed in early spring or late fall. You can strip the outer leaves one at a time or slice the whole rosette free at the 10 to 15 leaf stage.
Cool weather shapes how the plant grows. Between 50°F and 77°F (10°C to 25°C) the leaves stay broad and mild, but a cold snap in its first weeks or the heat and long days of summer drive a pale flower stalk up through the center and turn the leaves bitter. Sowings timed for spring and fall keep the plant leafy and low rather than stretched and flowering.
Once established it needs little. Give it steady moisture, fertile soil, and full sun, with partial shade still workable, and in a few weeks the stalks turn crisp and the leaves tender, ready for stir-fries and soups.
Care
The short version: full sun and cool weather, steady moisture of about an inch of water a week, rich soil worked with compost, and an early harvest at the 10 to 15 leaf stage before heat sets it bolting.
Light
Bok choy builds the broadest leaves and thickest stalks in full sun, which drives its fastest, fullest growth. On as little as 2 hours of direct sun a day it still forms usable heads, just smaller and slower, which makes it a fair pick for a part-shade bed.
Water
Keep the soil evenly moist with about 1 inch (2.5 cm) of water a week from rain or the hose, and more in sandy ground. That steady moisture is what fills the stalks until they snap crisp and holds off the flower stalk, so the bed should not swing from bone dry to soaked.
Soil
Those thick, juicy stalks are built on fertile ground that drains freely yet stays faintly damp, so fork through well-rotted manure or garden compost before sowing. Keep the pH at 6.0 to 7.5, raising it nearer 7 in beds where clubroot has shown up.
Temperature
This is a cool-weather crop, best between 50°F and 77°F (10°C to 25°C). Cold below 50°F in the early weeks can send up a flower stalk, and summer heat pushes the plant to flower and turns the leaves bitter.
Humidity
Ordinary outdoor humidity is fine, so there is no number to hit. Watch instead for warm, wet spells that ramp up pest and disease pressure, and give the leaves room for air to move between them.
Feeding
Work plenty of compost or well-rotted manure into the bed before planting and that carries most crops. On poor ground, a light nitrogen side-dress during growth keeps new leaves unfurling.
Pruning
There is no real pruning to do. Take the outer leaves as you need them or cut the whole head at the 10 to 15 leaf stage, and snap off the pale flower stalk the moment it appears at the center.
Size & spacing
Plants stand 6 to 12 inches (15 to 30 cm) tall in a low, spreading rosette about as wide. Thin dwarf types to roughly 12 inches apart and full-size plants a little more, so each leafy clump has room to fill out and stay airy.
When to plant
Bok choy is a cool-season crop whose leaves turn bitter and whose center shoots up a flower stalk in summer heat, so it grows in the cooler shoulders of the year. Sow indoors a few weeks before the last spring frost or direct-sow around it, then sow again in midsummer for a fall crop that fattens as the weather cools.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 4-5 weeks before the last spring frost for an early crop
- Plant: Set transplants out around the last spring frost once hard freezes have passed; direct-sow in midsummer (July) for a fall crop that matures in cool weather
- Harvest: Harvest 40-60 days after seeding at the 10-15 leaf stage, before hot weather triggers bolting; spring and fall crops
Hardiness
USDA hardiness zones: 2–11
Temperature: down to -46°C
Troubleshooting
Most bok choy trouble is written on the plant itself, in chewed leaves, slime at the stalk bases, or a tall stalk pushing up from the center. Reading those marks early lets you step in before the crop is lost. Match what you see below, then act while it still helps.
Leaves wilt and yellow even with enough water
Leaves that go limp and yellow while the soil stays moist are a sign the trouble sits below, in the roots. Clubroot swells them into useless gnarled clubs, while cabbage maggots tunnel pale channels through them and chew them apart. There is no curing a clubroot-struck plant, so lift it whole, destroy it, and keep it out of the compost.
Fix:
- Remove and destroy infected plants; do not compost them
- There is no cure for clubroot in an infected plant
A tall pale stalk rises from the center and leaves stop forming
A smooth pale stalk climbing fast from the heart of the plant, with no new leaves below it, is bolting. It follows a cold spell that tricks young plants into flowering or the heat and long days of late spring, after which the plant funnels its energy into that stalk and its buds. Cut the head before the yellow buds open and it is still edible, just a touch more bitter.
Fix:
- Harvest the head immediately, before the flowers open; it is still edible though it may be slightly bitter
Tiny round shothole holes peppering the leaves
A fine spray of round pinprick holes across the leaf blades is the mark of flea beetles, tiny shiny black beetles that spring off the foliage when brushed and chew hardest at tender seedlings. A floating row cover laid at sowing keeps them off the leaves. Steady water and quick growth let the plant push out new leaf faster than they can pit it.
Fix:
- Cover plantings with floating row cover at seeding
- Keep plants growing fast with steady water so they outgrow damage
Leaves torn ragged, dotted with dark green droppings
Torn-edged holes and scattered crumbs of dark green frass on the leaves point to cabbage caterpillars, among them the imported cabbageworm, the cabbage looper, and diamondback moth larvae. Look along the leaf undersides where their green bodies blend in, and pick them off. For a heavy run, coat the leaves with Bacillus thuringiensis while the caterpillars are still small.
Fix:
- Handpick caterpillars
- Apply Bacillus thuringiensis (Bt) while caterpillars are small
Slime trails and gnawed holes low on the stalks
Glistening silvery trails and chewed pits low on the thick stalk bases give away slugs and snails, which feed after dark in the damp, crowded crowns where the stalks pack together. Pick them off by hand at night or set out iron phosphate bait around the plants. Clearing mulch and debris from the stems strips away the cool, dark cover they hide under by day.
Fix:
- Handpick at night
- Use iron phosphate slug bait around plants
- Reduce mulch and debris immediately around stems
Toxicity
Bok choy is a kitchen vegetable, safe for people and not listed as toxic to cats or dogs. The only real caveat is quantity, since the natural goitrogens common to all cabbages can cause gas or mild upset if any animal eats large raw amounts often. Horses are the one to watch, as extension guides flag brassicas as a poor fit for their diet.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Bok choy is not on the ASPCA toxic list, so a cat that crunches a leaf comes to no harm. A large plate of the raw leaves might bring on some gas or a mild upset stomach, nothing more.
Dogs None
A dog can share a little cooked or raw bok choy without worry. The only catch is gas or loose stools if a dog wolfs down a large raw helping of the leaves at once.
Horses None
NC State Extension flags this plant as one to keep out of a horse's diet, since brassicas do not sit well with equines in quantity. A stray leaf is harmless, but it should not become a habit.
Rabbits None
Rabbits handle small servings of the leafy greens fine. Introduce the leaves slowly and keep portions modest, since too much rich brassica at once can leave a rabbit gassy.
Livestock None
Cattle, goats, and sheep can graze the leaves with no real danger. As with any brassica, a steady diet of nothing else can upset rumen digestion, so it belongs in the mix rather than as the whole meal.
Birds None
Backyard hens and other birds peck happily at the broad leaves and the bolted flowers. In moderation it is a wholesome green for them.
People Safe
Bok choy is grown to be eaten and is safe in the kitchen, the crisp stalks and tender leaves served raw in salads or cooked in a stir-fry. Only a steady habit of large raw amounts is worth a second thought, owing to the natural goitrogens shared across the cabbage family.
No special handling needed; safe to grow in household gardens.
Varieties
Bok choy comes with white or pale green stalks and in full-size and baby types. These are the ones worth knowing by name.
Shanghai (green-stem) type
The Shanghai type, called Shanghai Qing in China, sets spoon-shaped leaves on smooth pale green stalks rather than white ones and is often picked young as baby bok choy.
Dwarf types
Dwarf types form compact little rosettes around 6 inches tall, sit as close as 12 inches apart, and mature fast in a small space.
'Joi Choi'
'Joi Choi' is a vigorous hybrid with bright white stalks, prized for slow bolting and an easy way with both cold and warm spells.
'Mei Qing Choi'
'Mei Qing Choi' is a green-stemmed baby pak choi hybrid that resists bolting well.
Companions
Bok choy grows best beside onions and aromatic herbs that throw pest-laying moths off the scent, and it shares a cool-season bed comfortably with beets.
Plant near
Onions: Extension companion-planting guides note onions get along well with all cabbage-family crops, and onion interplanting helped reduce cabbage looper and imported cabbageworm damage in brassica trials
Aromatic herbs (dill, sage, thyme, chamomile, rosemary): Cole crops do well planted with aromatic herbs; sage and thyme reduced diamondback moth pressure on brassicas in studies
Beets: Extension companion charts list beets as compatible neighbors for cabbage-family crops in the cool-season bed
How to propagate
Bok choy is grown from seed, about as simple as sowing gets, with a fresh row ready to start every couple of weeks.
SeedEasy
Direct-sow or start indoors in early spring, and again in mid-to-late summer (around July) for a fall crop · Seed germinates in about 4-10 days in cool soil; plants reach transplant size in 3-4 weeks and harvest size in 40-60 days
Bok choy grows from seed and nothing else. Tuck the seed a quarter to half an inch deep in early spring or again around July for a fall crop, and the first thread-like seedlings break the surface in 4 to 10 days in cool soil. Thin to one plant every 6 to 12 inches by variety, then it takes 3 to 4 weeks for a leafy transplant and 40 to 60 days for a full stalk-and-leaf head. A fresh row every couple of weeks keeps young rosettes always coming on.
Myths
Once that pale flower stalk pushes up through the center, the leaves and stalks are spoiled and the plant is garbage.
A bolting plant caught in time is still good on the plate. Cut the head before the yellow buds open and it eats much like a young one, just a shade more bitter, and the tender flower stalks themselves are worth eating.
Only under full sun from dawn to dusk will bok choy fill out its stalks and leaves.
Full sun builds the broadest leaves and fullest heads, but the plant does not need it. As little as 2 hours of direct sun a day still yields usable heads, just smaller and at a slower pace.