How to Grow a Pak Choi

Garden bed

The garden bed is the right pick for larger quantities, succession planting through a long cool spring or fall, and growing baby leaves for repeated cuts. A 4 by 4 foot bed produces a steady supply for several weeks. Bed soil holds moisture more evenly than a pot, which suits this thirsty crop.

Pot

A 10 to 12 inch pot holds 1 to 2 full-size heads or 4 to 6 baby plants. Containers are useful for balconies, decks, and small-space growing. Pots dry out faster than beds, so plan to water more frequently in summer. Pick a wide shallow pot rather than a tall narrow one, since the roots run wide rather than deep.

Sun

Full sun in spring and fall, with six or more hours of direct light producing the heaviest tightest heads. In late spring or early summer when heat is rising, light afternoon shade extends the harvest window before the plants bolt.

Drainage

Well-drained soil prevents root rot and damping-off in cool wet weather. Pak Choi tolerates moist soil but suffers in standing water. Avoid spots where water sits after rain.

Soil

Rich loamy soil with plenty of organic matter is the natural preference. Work 2 to 3 inches of compost into the planting bed before sowing. Containers do best in a quality all-purpose potting mix with a handful of compost stirred in.

Crop rotation

Do not plant Pak Choi back into a spot that grew any cabbage-family crop in the last 2 to 3 years. Other cabbage-family crops include kale, broccoli, cabbage, kohlrabi, mustard, and turnips. Crop rotation breaks the disease cycle for soil-borne issues like clubroot and reduces pest pressure from cabbage worms.

Watering

Water deeply twice a week, soaking the root zone rather than splashing the leaves. Pak Choi has shallow roots and wilts quickly in dry soil. Drip irrigation or a soaker hose at the base works best for beds.

Container plants need water more often since pots dry out faster. Check the top inch of mix and water when it feels dry. Uneven watering causes split midribs and bitter flavor.

Feeding

Pak Choi is a moderate feeder. A side-dress of balanced fertilizer or a feeding of fish emulsion 2 to 3 weeks after thinning supports the heaviest leaf growth. Side-dress again at the 4 to 5 leaf stage for full-size heads.

Use a fertilizer with moderate nitrogen rather than a high-bloom formula. Leafy crops benefit from steady nitrogen, but avoid heavy doses that produce overly lush plants prone to disease.

Removing damaged leaves

Snap off any holed, yellowed, or pest-damaged outer leaves at the base of the plant. Discard rather than compost if cabbage worms or aphids are present. Removing damaged leaves keeps the plant looking clean and reduces hiding spots for pests.

Bolt watch

Once the weather warms above 75F or the days grow longer in late spring, the plants quickly send up a flower stalk. Once a plant has bolted, the leaves turn bitter and the head opens up. Harvest at the first sign of a flower stalk forming. Mulching to keep soil cool and providing afternoon shade slows but does not prevent bolting.

Cut-and-come-again harvest

For baby greens, cut the outer leaves about an inch above the soil and leave the crown intact. The plant regrows a second cut within 2 to 3 weeks. Two cuts is usually the limit before quality drops.

When it's ready

Baby leaves are ready when they reach 4 to 6 inches tall. Full heads are ready when the outer leaves stand 8 to 12 inches tall and the plant has formed a tight upright shape. Harvest before any sign of bolting, since flowering plants turn bitter fast.

Pick in the morning when the leaves are at their most crisp.

Picking and storing

Cut the whole head at the base with a sharp knife, leaving the roots in the soil. For baby greens, snip outer leaves with scissors. Wash leaves in cold water just before use to clean off any soil or pests.

Fresh Pak Choi stores in the refrigerator for 5 to 7 days. Wrap loosely in damp paper towels inside a perforated plastic bag for the longest storage. The leaves wilt quickly at room temperature, so refrigerate promptly after picking.

Succession planting

Sow a fresh row every 2 weeks through the cool growing window to keep a steady supply coming. Spring sowings can run from 4 weeks before the last frost up to 2 weeks after. Fall sowings can run from 8 weeks before the first frost up to 4 weeks before.

Flea beetle holes

Tiny shotgun holes in the leaves from small black jumping beetles. Light damage is cosmetic, but heavy infestations stunt seedlings. Cover young plants with floating row cover from sowing until they fill out. Yellow sticky cards trap adults and dust-bath with diatomaceous earth or kaolin clay deters feeding.

Cabbage worms

Green caterpillars chewing irregular holes in the leaves, often with green frass scattered around. Hand-pick small populations. Heavier infestations respond to Bacillus thuringiensis spray, which kills caterpillars without harming bees. Cover plants with floating row cover from planting through harvest to exclude the white cabbage butterfly that lays the eggs.

Aphids on new growth

Clusters of small green or gray insects on the undersides of new leaves and the crown. Knock them off with a strong water spray every few days. Heavier infestations respond to insecticidal soap. Beneficial insects like ladybugs and lacewings clear most aphid pressure on their own.

Slug damage

Ragged holes in the leaves overnight with silvery slime trails. Hand-pick slugs after dark with a flashlight, or set out shallow saucers of beer at soil level as a trap. Iron phosphate slug bait is a pet-safe option for heavier infestations.

Bolting early

Plants send up a flower stalk and turn bitter. Caused by heat above 75F, long day length, or stress from transplanting and uneven watering. Sow at the right time for the zone, mulch to keep soil cool, and water steadily. Once bolted, harvest immediately for stir-fry use.

Split midribs

Thick stems crack along the length, usually after a heavy watering or rain after a dry stretch. Water evenly through the growing window rather than alternating drought and soaking. Mulch helps even out soil moisture.

Yellowing lower leaves

Most often nitrogen deficiency on lean soils or aging outer leaves on near-mature plants. Side-dress with fish emulsion or a balanced fertilizer if the yellowing affects the whole plant before harvest. Yellow outer leaves on mature plants are normal and can be trimmed off.

Damping-off in seedlings

Young seedlings collapse at the soil line and die. Caused by overly wet soil and poor airflow. Sow on the surface rather than deeply, water lightly, and avoid sowing in cold wet weather. Damping-off-affected seedlings cannot be saved, but the rest of the row usually recovers as the soil dries.

Clubroot

Plants wilt despite damp soil and the roots show grotesque swollen lumps when pulled. A soil-borne disease that persists for years. Rotate out of all cabbage-family crops for at least 3 years where infected. Lime the soil to raise pH toward neutral, which slows the disease.