Water Spinach

Water spinach (Ipomoea aquatica), also known as kangkung or kang kong, is a semi-aquatic tropical leaf vegetable prized for its tender shoots, stems, and leaves. A close relative of sweet potato, it produces attractive white flowers and grows vigorously in fertile, permanently moist soil. It thrives in hot, humid conditions and is frost-tender, making it a warm-season crop that requires supplemental heat in temperate climates. The leaves and stems are rich in iron and vitamin A.

Growing

Start seeds indoors in a seedling tray once indoor temperatures are consistently above 20 °C, sowing 0.5 cm deep. Soil temperature must reach 25–30 °C for reliable germination, which occurs in 3–10 days. Pot on or transplant outdoors only once night temperatures remain above 20 °C and all frost risk has passed. Space plants 30 cm apart in fertile, moisture-retentive soil with a pH of 6–7. Water spinach can also be grown as a bog plant at the edge of a pond or in a large pot with its rim at water level.

Care

Keep soil permanently moist — water spinach will not tolerate dry conditions. Apply an organic liquid fertiliser monthly throughout the growing period. Position in full sun or semi-shade; in northern climates, a sheltered, south-facing spot maximises heat. Mulch heavily to retain moisture. The plant can become invasive if introduced to open water bodies, so contain roots carefully when growing near ponds.

Harvest

Begin harvesting young tips, stems, and leaves once plants are established and actively growing — individual shoots can be taken well before the 45-day whole-plant maturity point. Snap or cut the top 15–20 cm of stems; the plant will re-sprout from lower nodes, allowing repeated harvests over a 30-day or longer window. Harvest regularly to keep new growth tender and productive.

In the kitchen

Use raw young leaves in salads or cook stems and leaves quickly in a hot stir-fry with garlic, chilli, and soy sauce — the classic Southeast Asian preparation. Steaming or blanching preserves the bright green colour and delicate texture. Stems are slightly firmer than leaves; add them to the pan first. Water spinach pairs well with oyster sauce, fermented shrimp paste (belacan), and sesame oil.

Storing

Use freshly harvested shoots as soon as possible for best flavour and nutrition. Unwashed stems and leaves keep for 2–3 days wrapped in damp paper and stored in the crisper drawer of a refrigerator. Do not freeze; the leaves turn mushy when thawed. For longer preservation, blanch briefly and freeze for up to one month.