Products - Ong Choi (Ipomoea aquatica)

Ong Choi (Ipomoea aquatica), is a member of the Morning Glory family (Convolvulaceae). The most common varieties are bright green and grow up to 14 inches tall. Ong Choi is of East Indian origin and a member of the Convolvulaceae (morning glory) family. Ong Choi is extremely popular in Southern China, Vietnam, Malaysia and Thailand. Ong choi in Chinese literally translates as "hollow vegetable". Although Ong Choi is closely related to sweet potato (Ipomea batatas) and convolvulus, it has no relationship with the common spinach.

The Ong Choi has jointed and fleshy green hollow stems allowing the vines to float on water or creep across muddy ground. The roots are formed at nodes which are in contact with water or moist soil. Ong Choi can be either white or green, depending on variety and exude a milky juice. This plant only grows in wetlands and is able to grow across water as the hallow stems float and the roots do well under waterlogged conditions.

The leaves are flat, triangular and heart-shaped, and vary in shape depending on variety, from heart-shaped to long, narrow and arrow-shaped. Narrow leaves are 1-2.5 cm wide and 20-30 cm long. Broad leaves are up to 5 cm wide and 15-25 cm long.

The flowers are tubular and white to purple, and have the typical open, trumpet shape of convolvulus or bindweed flowers. Usually white, sometimes with a pinkish centre, although Wild forms may have purple or mauve flowers. The seeds are large with a hairy exterior.

In Kenya it grows in the Lake Basin and along the coast. The plant is easily grown from stem cuttings and seeds are occasional marketed. The cuttings are rooted and then transplanted into wetlands, stream banks, pond walls or poorly drained areas, it grows very rapidly and the leaves and young shoots may be harvested regularly throughout the year.

The leaves have a very pleasant, mild, sweet flavour and a slightly slippery texture, which contrast when cooked with the crispness of the stems. The Chinese consider the white stemmed forms better flavoured and tenderer than the green.

Ong Choi can be grown year-round in the tropics. However, will adapt to climates with mean temperatures below 10C. Flowering usually occurs Under short-day conditions and from mid-summer onwards commences. In warm climates Ong Choi is perennial, but under cooler growing conditions an annual crop. Very high rainfall can be tolerated, but not frost. The natural habitat is water or swampy land. Ong Choi can be grown outside in summer. In areas with cooler climates, it can be grown in unheated greenhouses in summer, but will need heated greenhouses for a spring crop.

Under low light levels typical of European winters, Ong Choi will not grow well, even if temperatures are high. Ong Choi should ideally be grown in full sun and where summer temperatures are very high. Sometimes it is grown as a ground cover beneath climbing plants. Ong Choi should be sheltered from strong winds.

If grown in moist soil type culture, Ong Choi crop is grown on raised beds 60-100 cm wide. The seeds are directly sown, or nursery-grown seedlings about 10-15 cm tall are transplanted into the beds. The seeds should not be more than 2 years old. Soaking the seeds for 24 hours before sowing will encourage germination. The soil temperature requirement for germination is 20C.

In aquatic type culture, the furrows between the beds are flooded very soon after seeding or transplanting. If rainfall is low, frequent heavy irrigations are necessary for high quality shoots.

Ong Choi should be harvested before it flowers. In the semiaquatic type culture, the crop is ready for harvest 50-60 days after sowing. The entire plants are pulled, washed and bundled. If shoots are cut above ground level more than one harvest can be taken. This allows secondary shoots to grow from nodes below the cut.

In the aquatic type, after a month of good growth the first harvest can be made. The regularity of harvesting will depend on the growth rate of the crop. The upper part of the main shoot is about 30 cm long and is cut about 5 cm above water level. The removal of the main shoot stimulates horizontal shoot growth. Then depending on plant vigour and temperature these new shoots can be harvested in 4-6 weeks. Approximately 40 tonnes/ha can be harvested from three or more cuttings in a year.

In order to minimise damage to the fragile crop, rapid and careful post-harvest handling is required. This is especially due to wilting caused by moisture loss. A prevention would be to harvest the plant during the coolest part of the day. Following bunching, a fine spray of cold water should be applied, and the leaves kept in a cool place away from the wind.

Leaves are usually sold in 500 gram bunches in the markets.

Morning Glory, Water Spinach, Kankun, Kong Xin Cai (Kong Shin Tsai), Chau Gan Choi, Rau Muon, and Swamp Cabbage.

Lightly boil, steam, stir-fry with shrimp paste, combined with other greens and used in soups. Ong Choi deteriorates rapidly once picked, so ideally it must always be used very fresh. The leaves can be used whole, or cut into smaller pieces and like ordinary spinach, the stems require slightly longer cooking than the leaves.

Almost all parts of the young plant are eaten, although the shoot tips and younger leaves are preferred. Older stems that are from plants cultivated on dry land, contain considerable fiber and therefore the cultural methods emphasize the production of young succulent tips.

In the West, Ong Choi is treated as ordinary spinach. It is sauteed with butter and garlic, or with bacon, and tossed with a little vinegar and sugar. In contrast, the Chinese will consume this vegetable in a variety of ways such as in soup, batter fried, or raw.

The Cantonese exclusively stir-fry it, with a generous amount of garlic (or garlic shallots) and either white fermented bean curd or fermented shrimp sauce; chilli is commonly added.

Try our Ong Choi recipes: Ong Choi with Sprimps and Stir Fried Garlic Chilli Beef and Ung Choi (Kong Xin Cai in Mandarin) (Morning Glory/Water Convolvulus in English).

UK: June - Mid September      

Similar to many other leafy vegetables, Ong Choi's leaves are very nutritious. It is rich in vitamins and minerals. They are also a mild laxative.

The leaves and young stems are eaten as a green vegetable and cooking requires only a few minutes. The leaves contain 3% protein and are high in vitamin B.