Type: Leafy Greens
Difficulty: Easy
Season: Spring·Fall
Sowing: From seed

Leafy Greens

Bok Choy (Cheonggyeongchae)

Brassica rapa

Calcium and vitamin C in an easygoing leafy green

Bok choy ranks high in calcium for a leafy green, and it carries vitamin C, vitamin A, and beta-carotene as well. The crisp stalks have a mild flavor that slips easily into stir-fries, soups, or fresh wraps. Because it matures quickly, you can direct-sow it in spring or fall and harvest in short order, which makes it a forgiving pick for first-time gardeners.

Year-Round Calendar

Sowing

Harvest

Where It Grows

Origin Major producer Latitudes at 18–20℃ Zoom and pan to explore · temperatures are rough zonal averages

Origin The crop branched off in the lower Yangtze region (Shanghai, Jiangsu, Zhejiang), and China still accounts for most of the world's production and consumption. In Central and South China it is grown year-round.
Major producer It arrived in the 1970s and became a standard vegetable. Shizuoka, Ibaraki, and Nagano are the main growing areas.
Major producer Known there as xiaobaicai ("little white cabbage"), it is a major leafy vegetable grown year-round.

The crop originated in the lower reaches of China's Yangtze River. Because it is a subspecies of the same species as napa cabbage (Brassica rapa), it has no separate entry in FAO statistics and is lumped in with the cabbage group, so it is safest to assume no global production statistics exist for bok choy alone. It reached Korea in the 1980s.

Optimum: 18~20℃
Range: 5~25℃
Hardiness: Half-hardy

Bok choy prefers a cool climate. With only 30–50 days from planting to harvest, it can be sown in several successive batches in spring and autumn, while in midsummer heat above 25℃ the leaves grow thin and the plants become prone to soft rot. Young seedlings exposed to low temperatures for too long will bolt, sending up flower stalks.

In Korea Nationwide

Because its growing period is so short, farmers use both open-field cultivation in spring and autumn and year-round greenhouse growing. Greenhouse complexes in Icheon and Pyeongtaek in Gyeonggi Province, in South Chungcheong, and in Miryang in South Gyeongsang supply it in every season.

How to grow

Light: Sun is good, but it tolerates part shade
Soil and depth: 15cm deep. Happy in a pot
Spacing: 15cm
Watering: Often. Dry plants turn stiff and bitter
Feeding: It grows so quickly that the base dressing is usually enough
Harvest: Lift the whole plant 30 to 40 days after sowing. Baby leaves are good too

What makes the difference. One of the fastest crops there is. Useful for filling a gap in the bed

Common problems

Cabbage white caterpillars You will see Holes in the leaves What to do Netting is the better answer
Flea beetles You will see Countless pinprick holes What to do Cover with fleece while it is young and let them pass

This page describes how a crop is grown and used. It does not claim health effects for any food, nor is it intended to prevent or treat disease. Component and study notes are references only and do not mean the same result occurs in people. Consult a medical professional about health concerns.

Health Benefits

Glucosinolates. Bok choy contains the glucosinolates shared across cruciferous vegetables. Epidemiological studies have reported on the relationship between cruciferous intake and the incidence of several cancers, but that does not mean eating this vegetable has anything to do with preventing or treating disease.

Calcium absorption. Experiments have reported that the calcium in bok choy is absorbed at a comparatively high rate. That stands in contrast to spinach, where high oxalic acid holds absorption down, and it is why bok choy comes up as a plant calcium source in diets without dairy.

Carotenoids. Bok choy contains beta-carotene and lutein, and it is established that lutein accumulates in the retinal macula. That does not mean eating this vegetable wards off any particular eye disease. Carotenoids are absorbed better when cooked with a little oil.

Potassium and dietary fiber. Potassium and dietary fiber are present together. Nutrition research discusses them in connection with sodium excretion and bowel movement respectively, but no basis has been established for saying that eating bok choy alters blood pressure or cholesterol.

The scope of isothiocyanate research. When the leaf is crushed, glucosinolates break down into isothiocyanates. Compounds in this class have been reported to induce phase II enzymes in laboratory and animal studies, but that cannot be extended to what happens when a person eats bok choy.

Nutrition

Calcium (High for a leafy green) — A mineral it is high in for a leafy green
Vitamins C and A (Abundant) — Water-soluble and fat-soluble vitamins
Beta-carotene (Present) — A carotenoid pigment

Glucosinolates & isothiocyanates Bok choy contains the glucosinolate class shared across the Brassica family. The class is shared, but the individual compounds differ by species: in the Brassica rapa group to which bok choy belongs, gluconapin, progoitrin and glucobrassicin are reported as the main forms. When the leaf is damaged or chewed, the enzyme myrosinase breaks them down into isothiocyanates, compounds examined in research on phase II enzyme induction and related activity.

Vitamin K Bok choy contains vitamin K, a fat-soluble vitamin. Nutrition research discusses vitamin K in connection with blood clotting and bone metabolism, and because it is fat-soluble, a little oil in the cooking improves absorption.

Vitamin A (beta-carotene), C & folate Among leafy greens, bok choy ranks high in vitamin A (beta-carotene), vitamin C and folate. All three nutrients are discussed in research on immune function, mucosal tissue and cell division, and so belong to everyday nutrition.

Calcium Raw bok choy carries about 105 mg of calcium per 100 g, which is high for a leafy green. A head is small, though, and it collapses in the pan, so the per-100 g figure and the amount that actually lands on a plate are worth holding apart. Minerals leach into cooking water, so a short toss over high heat or a quick blanch loses less than a long boil. The white stalks take longer to soften than the leaves: start the stalks first and add the leaves at the end.

Potassium, magnesium & dietary fiber Potassium, magnesium and dietary fiber are present in balanced amounts; nutrition research discusses potassium in connection with sodium excretion, and fiber with bowel movement. Calories are low for the bulk, so the vegetable brings fullness and nutrients at the same time.

Low calorie At about 13 kcal per 100 g, raw bok choy is low in calories for its bulk. Its mineral and vitamin density is not low for a leafy green, so on composition alone it sits on the low-calorie, micronutrient-carrying side.

Pairings

○ Garlic, ginger, and soy sauce — A quick stir-fry with garlic, ginger, and soy sauce, or with oyster sauce, is a Chinese-cooking staple. The pungent, savory seasoning meets bok choy's mildness to make a side dish with real flavor. Garlic · Ginger

○ Oyster sauce and sesame oil — The umami of oyster sauce and the nutty aroma of sesame oil are the heart of Cantonese-style stir-fried bok choy. A short, fast cook keeps the crunch, setting the firm stalks against the tender leaves.

○ Chicken and shrimp — Stir-fried with white-meat proteins like chicken or shrimp, bok choy rounds out the balance of protein and minerals. Its mild flavor absorbs the punch of the seasoning, evening out the whole meal.

○ Tofu — Served with tofu, as in mapo tofu or bok choy and tofu stir-fry, the dish gains plant protein and calcium. The contrast between soft tofu and crisp bok choy adds depth to a one-bowl meal.

○ Lemon and vinegar — A light touch of lemon or vinegar boosts vitamin C and brightens the leaves. The acidity also helps stabilize carotenoids and slows discoloration.

△ Thyroid conditions, blood thinners, and kidney failure — Three groups should watch their intake: people with hypothyroidism, because glucosinolates may interfere with thyroid hormone synthesis; warfarin users, because the vitamin K content can throw off the drug's effect; and people with kidney failure, because of the potassium load. Cooking bok choy largely neutralizes the thyroid concern.

Varieties

Cheonggyeong type (green-stalk) (Seed) — The common green-stalked kind; crisp and mild, fitting stir-fries and soups alike.
Baekgyeong type (white-stalk) (Seed) — Wide white stalks and softer leaves than the green-stalked kind, quick to soften in broth.
Mini bok choy (Seed) — Harvested at palm size, ready to pull whole about a month after sowing.

Source: Food and nutrition references