Pak Choi, Bok Choi 'Shanghai'

Pak Choi or Bok Choy 'Shanghai' is a special green stem variety with glossy, dark green leaves, thick green petioles and an attractive hourglass shape. The thick petioles are extra tender and finely flavoured.
High yielding and tolerant of extremes in temperature this variety is very popular in southern China and Southeast Asia where it is known as Shanghai Bok Choy, while in the commercial world today they are popularly labelled as Baby Bok Choy.
Unlike the white stemmed varieties of Pak Choy, 'Shanghai' are green, which is why the Shanghaiese locals refer them as Qing Jiang Cai or Qing Cai, meaning 'green vegetable'.

Shanghai Bok Choy are increasingly grown in Northern Europe. This new 'celebrity' Chinese vegetable grows exceptionally quickly, tolerates both cold and heat and can be sown in succession for crops nearly all season long.
Shanghai Bok Choy are tender and delicious, usually harvested when around 15cm (6in) tall, the mild flavour is sweet with a hint of mustard. They have a much softer texture than white stemmed varieties and are much easier to cook since their stems and leaves are similar in size and can be cooked together so minimum cooking time is required.
The leaves can be used raw or cooked from any stage and are perfect for adding to a microgreens mix, larger leaves can be used in salads or it can be left to mature and used in stir-fries. They go well with the flavours of soy sauce, hot peppers, and toasted sesame oil. Young flowering stems can be used like broccoli or as a substitute for spinach. Harvest in 20 to 25 days for baby leaf or 40 to 50 days to maturity.

Position:
Pak Choi grows best in a sunny position in a fertile soil.
It can be sown directly into open ground or can be planted into grow bags

Sowing: Pak Choi can be grown all year
Pak choi is a cool-season crop typically grown in autumn and early winter, though in warmer climates harvest can continue well into winter. It will germinate at temperatures between 13 to 24°C (55 to 70°F).
These green stemmed varieties withstand adverse conditions than white stemmed forms. Some protection is required for winter harvesting. Phasing the sowing will extend the cropping period.

Sow thinly, direct into finely raked, moist, weed free soil 6mm (¼in) deep in rows 30cm (12in) apart. Thin the resulting seedlings, leaving the strongest, by degrees to a final spacing of 20cm (8in) apart.

Tending:
It is important to water well in dry weather and to keep well weeded. Provide a weak liquid feed once a week.
It needs to be grown quickly and the roots must be kept moist. Checks to growth, brought on by overcrowding or drought, will cause plants to bolt. They are snail magnets, so plants need protection in the open garden.

Harvesting:
Plants reach a stage for baby leaf harvest in 28 days and mature plants take around 50 days. Chop off enough of the base of the bok choy plant before washing so that stalks can be cleaned individually.

Storage:
Pak choi generally keeps well and will stay fresh for more than a week, but should be used in four to five days for best flavour.

Culinary Use:
Pak choi stalks can be consumed raw, or cooked. It has a high water content and becomes limp very quickly so should be cooked very quickly over high temperature so that the leaves become tender and the stalks stay crisp.
In Chinese stir-fried dishes and soups, it is added toward the end of the cooking process. Since the leaves cook much more quickly than the stalks, it’s a good idea to add the stalks first and then the leaves about a minute later. Cut the stalks into 1.25cm (½in) pieces before cooking.

Origin:
The Chinese cabbage was principally grown in the Yangtze River Delta region, but the Ming Dynasty naturalist Li Shizhen popularised it by bringing attention to its medicinal qualities. These vegetables are both variant cultivars or subspecies of the turnip and belong to the same genus as such Western staples as cabbage, broccoli, and cauliflower. Both have many variations in name, spelling, and scientific classification, especially the bok choy (B. rapa chinensis) variety.
Chinese cabbage is now commonly found in markets throughout the world, catering both to the Chinese diaspora and to northern markets who appreciate its resistance to cold.

Nomenclature:
Chinese cabbage (Brassica rapa, subspecies pekinensis and chinensis) can refer to two distinct varieties of Chinese leaf vegetables often used in Chinese cuisine: Pekinensis (napa cabbage) and Chinensis (bok choy).
Pekinensis cabbages, usually called Napa cabbages have broad green leaves with white petioles, tightly wrapped in a cylindrical formation and usually forming a compact head. As the group name indicates, this is particularly popular in northern China around Beijing (Peking).
Chinensis varieties do not form heads; instead, they have smooth, dark green leaf blades forming a cluster reminiscent of mustard or celery. Chinensis varieties are popular in southern China and Southeast Asia. Being winter-hardy, they are increasingly grown in Northern Europe. This group was originally classified as its own species under the name B. chinensis by Linnaeus.
What most of us call 'bok choy,' in China it is often called 'bai cai' and pronounced 'ba chai'.