Water Chestnut

Eleocharis dulcis, the Chinese water chestnut, is a grass-like sedge native to Asia, tropical Africa, and Oceania, grown for its crisp, sweet edible corms. The plant produces upright hollow stems reaching 100–150 cm tall and thrives in waterlogged conditions, similar to paddy rice. Each plant can yield up to 50 corms with a flavour reminiscent of fresh coconut. Slightly acid to neutral soils (pH 5.9–7.3) are preferred, and the crop requires a long frost-free growing period of at least 210 days.

Growing

Start corms indoors in containers of water or wet growing medium once air temperatures remain reliably above 15 °C. Plant corms 5 cm deep in heavy, slightly acidic to neutral soil within a barrel, pond, or plastic-lined container that can hold up to 10 cm of standing water. Space plants 30 cm apart. Gradually increase water depth as shoots emerge, maintaining 5–10 cm of water above the soil surface throughout active growth. Water level must be controllable to allow drainage at harvest.

Care

Maintain a consistent water level of 5–10 cm above the soil throughout the growing season — allow no drought periods. Feed with a balanced aquatic or slow-release fertiliser once shoots are established. Remove any yellowing or dead stems promptly. Protect plants from frost at all costs; the crop requires a minimum of 210 frost-free days. In cooler climates, maximise heat by positioning containers in the most sheltered, sunniest spot available.

Harvest

Harvest when aerial stems have fully yellowed and died back, indicating corm maturation. Drain the water from the container, then dig or rake through the soil to retrieve corms. Corms are ready once the outer skin has turned dark brown. Handle carefully to avoid bruising. Each plant typically produces up to 50 corms. Where winters are mild, corms can be left in the soil and harvested as needed.

In the kitchen

Chinese water chestnuts are delicious eaten raw, sliced into salads, or added to stir-fries, soups, and dumplings. Their texture remains pleasantly crisp even after cooking. Always wash and peel thoroughly before eating raw to remove any surface contamination. They pair well with ginger, soy, and fresh herbs.

Storing

Store harvested corms unwashed in soil or damp sand in a cool location at around 4 °C for up to six months. Alternatively, peel, blanch, and freeze for longer-term storage. Refrigerate peeled corms submerged in water for up to one week, changing the water daily.