Pak choi is grown for its edible pale green stalks and leaves.
Baby leaf varieties should be harvested when 50-100mm (2"-4") tall.
Plants should be treated in a similar manner to lettuce, i.e. sow a little often to get a succession of young tender leaves/stalks.
It should be grown quickly and the roots kept moist at all times, any check in growth, brought on by overcrowding or drought, will cause plants to bolt.
For this reason direct sowing is the best option, although they can be grown in cells / pots for an early crop.
Mature Pak choi
The plants will need protection from slugs and snails, particularly after the seedlings have just emerged.
Growing them in raised pots or growbags can help to alleviate the slug problem.
For an early crop fill a modular cell tray with seed compost and sow a tiny pinch of seed in each cell.
Alternatively, growing a few in 125-150mm (5”-6”) pots and growing on in a cool greenhouse will produce an earlier crop of leaves, these can be cut whole for eating when they are relatively small and succulent.
Once germinated (approx 4-5 days) allow the seedlings to grow to approx 25-50mm (1”-2”) high, then thin them out to leave the strongest seedling in each cell.
Plant out the plug plants outdoors when all fear of frost has past, plant them 200-300mm (8”-12”) apart in a prepared bed.
Alternatively, sow seed very thinly in a well prepared seedbed and thin out as necessary to avoid overcrowding.
Keep moist at all times to prevent bolting, and provide a weak liquid feed once a week.