Leafy brassica
How to grow pak choi
Brassica rapa subsp. chinensis
Pak choi is one of the fastest vegetables you can grow, ready as baby heads in five weeks, but it bolts at the first check. In the UK the reliable sowing window is late July to September, in rich, moist soil, for cutting through autumn. Spring sowings need a bolt-resistant variety, modules and constant water. Cover every sowing with fine mesh against flea beetle and never let the roots dry out.
- Hardiness
- Half-hardy; bolts in heat, survives light frost
- Position
- Light shade in summer, sun in spring/autumn
- Soil
- Rich, moisture-retentive
- Ideal pH
- 6.5 to 7.0
- Water
- High, dry roots trigger bolting
- Feeding
- Moderate feeder
Sowing and planting pak choi
WhenSow Apr to May (bolt-prone) and Jul to Sep (best); harvest 4 to 8 weeks later
Starting off
Direct every 3 weeks from late July to September for the main crop, or in modules at 15 to 20 °C and planted out at 3 weeks; germination takes 4 to 8 days. April to May sowings bolt unless given shade and water, so choose bolt-resistant 'Joi Choi' and sow in modules only. September sowings under cover crop into December.
Spacing and planting
Sow 1 to 2 cm deep in drills 30 cm apart and thin to 10 cm for baby heads, 20 to 25 cm for full-size; or sow 5 cm apart for cut-and-come-again leaves. Excellent in a 20 cm deep trough or 25 cm pot, where moisture is easier to control.
Varieties worth growing
- Joi Choi F1
- Large white-stemmed type with good bolt resistance. The safest choice for a spring sowing and tolerant of cold in autumn.
- Mei Qing Choi F1
- Compact green-stemmed (Shanghai) type, picked as a 15 cm baby head. Quick, uniform and well suited to pots and close spacing.
- Red Choi F1
- Maroon-topped leaves with green undersides. Good as baby leaf in a salad mix or grown on for a small head.
- Canton Dwarf
- Short, squat white-stemmed heads with dark crinkled leaves. Handles summer warmth better than tall white types.
- Tatsoi
- A flat, rosette-forming relative with spoon-shaped leaves. Much hardier than true pak choi and the one to grow for winter picking under cover.
Pak choi month by month
Timings are for central England. Allow two weeks later in the north and on cold, heavy soil.
- January
Nothing to do. Pick tatsoi under cover.
- February
Nothing to do. Order seed, including a bolt-resistant variety.
- March
Nothing to sow yet outdoors. Prepare a bed with compost.
- April
Sow Joi Choi in modules under cover at 15 to 20 °C. Cold nights now cause bolting later.
- May
Plant out April modules under mesh. Water daily in dry weather. Cut as baby heads rather than waiting.
- June
Harvest spring plants before they bolt. No sowing in the longest days.
- July
Start the main sowings from late July, direct or in modules, under mesh.
- August
Sow every three weeks. Thin to 10 cm for baby heads or 20 to 25 cm for full size. First harvests.
- September
Last outdoor sowing early in the month. Sow under cover for cutting to December.
- October
Harvest. Cover late outdoor rows with cloches or fleece before the first frost.
- November
Cut the greenhouse crop. Pak choi stands light frost but not a hard freeze.
- December
Finish the last heads under cover. Clear the bed.
Feeding pak choi
A hungry, shallow-rooted crop that is in the ground for only six to eight weeks, so most of the feed goes in before sowing. Fast, unchecked growth is what prevents bolting, and water does more for that than fertiliser.
A nitrogen-leaning feed for fast, leafy growth.
Feeding plan
Before sowing or planting
Garden compost
A 5 cm layer forked into the top 10 cm to hold moisture around the shallow roots.
A week before sowing or planting
Fruit & Vegetable Fertiliser 4-5-6
100 g/m² raked in, within the 70 to 110 g/m² label range. With rows 30 cm apart that is 30 g per metre of row (100 × 0.3).
Three weeks after sowing, full-size heads only
Organic Nitrogen Fertiliser 13% N
25 g/m², the low end of the leafy-crop rate, between the rows and watered in: about 8 g per metre of row (25 × 0.3). Once is enough for a crop this short. Baby heads cut at five weeks do not need it.
Pots, three weeks after sowing, full-size heads only
Fruit & Vegetable Fertiliser 4-5-6
2 g per litre of pot volume, the low end of the label, scattered on the compost and watered in: 40 g for a 20 litre trough (2 × 20). Once; the crop is cut before another would be due.
Signs to watch
Brown, scorched inner leaf edges
Tipburn from fast growth and erratic water under heat
Water daily and shade in summer
Bolting to flower within weeks
Long days, cold nights or dry soil after an early sowing, not feeding
Sow after midsummer
Pale, slow leaves in autumn
Nitrogen short
A light top-dress of the dry feed in the feeding plan, watered in
Pests, diseases and problems
Leaves peppered with small round holes, seedlings stunted or killed
Flea beetle, worst from April to August in dry weather
Cover with fine insect mesh from the moment of sowing or planting and seal the edges. Keep the soil moist so plants grow through any damage quickly.
Seedlings eaten off overnight, slime and holes in the stems of maturing heads
Slugs and snails, which feed inside the head
Start in modules and plant out at three weeks, hand pick after dark, and use nematodes on moist soil from April to September. Cut heads as soon as they are ready.
Plants wilt in sun, stop growing and pull out easily with few roots
Cabbage root fly maggots eating the roots
Fine mesh over the crop from planting keeps the fly from laying. Put the mesh on before the plants go in, not after.
Large holes and green droppings in the leaves from July to October
Caterpillars of cabbage white butterflies and cabbage moth
Keep the mesh on until harvest. On uncovered plants, pick off eggs and caterpillars twice a week.
Plants stunted and wilting, roots swollen and distorted
Clubroot
No cure. Remove plants and roots, keep brassicas off that soil, and grow pak choi in containers of fresh compost. On acid soil where a pH test confirms the need, liming before brassicas reduces the risk.
Outer leaves rot at the base under cover in late autumn
Grey mould and bacterial soft rot in cold, damp, still air
Water in the morning at soil level, ventilate freely, remove yellow leaves, and harvest whole heads before the coldest weather.
Harvest and rotation
Harvest and storage
Cut baby plants whole at 8 to 10 cm, 4 to 5 weeks from sowing, or full heads at 6 to 8 weeks; alternatively take outer leaves and leave the centre, or cut 2 cm above the base for regrowth. A 1 m row yields 10 to 12 heads of 150 to 300 g. Use within 3 days from the fridge in a bag; it does not store.
Rotation and companions
Rotation: brassica group, 4-year gap, but a short crop that slips between other brassicas in the same year. Sow after early potatoes or garlic are lifted.
Good to knowBolts in heat and drought, sow late summer for an easy autumn crop and keep it moist.
Growing pak choi in pots
Pak choi does well in containers because you control the water. Use a trough or pot at least 20 cm deep filled with peat-free multipurpose compost, with Fruit & Vegetable Fertiliser 4-5-6 mixed in at 5 g per litre: 100 g for a 20 litre trough. Space baby heads 10 cm apart, or grow three full-size plants in a 30 cm pot. Water every day and twice in hot weather; one afternoon of dry compost is enough to trigger bolting. Stand summer pots where they get shade from midday, and drape mesh over them, since flea beetle finds pots as well.
Pak choi: common questions
Why does my pak choi bolt?
Pak choi bolts when it is stressed while the days are long: by cold nights after an early sowing, dry roots, heat or root disturbance at transplanting. Sow from late July onwards when the days are shortening, keep the soil constantly moist, and for spring crops use Joi Choi raised in modules and planted out without a check.
When should I sow pak choi in the UK?
Late July to early September is the best time, for harvests from late August into November. April and May sowings are possible with a bolt-resistant variety, and a September sowing in a cold greenhouse crops into December.
Can you still eat pak choi that has bolted?
Yes. Cut it as soon as you see the flower stem rising: the leaves, stem and unopened buds are all edible and are good stir-fried, though the flavour gets stronger and the stalks tougher once the flowers open.
Sources
Growing information on this page was checked against these references in November 2026. Feeding rates are Dr Forest label rates.