Water spinach also known as kangkong, kangkung and water convolvulus, originates from tropical Africa, India and Southeast Asia. In these regions, it is grown under ideal conditions with very moist soil and temperatures between 25 and 35 °C. Although it is a perennial plant in its native habitat, it can only be grown as an annual in the Dutch climate. Water spinach is not related to true spinach. Instead, this fast-growing tropical leafy vegetable belongs to the morning glory family and is closely related to the sweet potato. Despite its name, water spinach does not have to be grown in water. As long as the soil is kept consistently moist, it can be grown outdoors in a sunny, sheltered location. The plant has long, flat green leaves and hollow stems. Its flavour is often described as a cross between spinach and endive. Water spinach is widely used in Asian and Surinamese cuisine. Although water spinach is sometimes considered an invasive plant, this can easily be prevented by growing it in large containers or pots. It is important to ensure that the plants never dry out. Removing the flowers before seeds develop is another effective way to prevent unwanted spreading. An additional benefit is that the plant will continue producing tender leaves and young stems for a longer period.
Water spinach is highly nutritious and contains a wide range of vitamins and minerals, including vitamins A, B1, B2, B5, B6, B9 and C, as well as calcium, phosphorus, iron, potassium, copper, magnesium, manganese, sodium, selenium, zinc and sulphur. It also contains various amino acids, proteins and carbohydrates, while remaining low in calories, like many other leafy vegetables. Water spinach can be prepared in much the same way as spinach and is delicious stir-fried, steamed or lightly braised. The young leaves can also be eaten raw in salads. Avoid using older stems, as they become very fibrous. For the best flavour, prepare the leaves as soon as possible after harvesting. They can be stored for 1 - 2 days in the vegetable drawer of a refrigerator when kept in a plastic bag or wrapped in damp kitchen paper. Non hardy perennial. Height: 25 - 55 cm.
Pre soaking: 6 - 12 hours
Indoor sowing: April - May
Germination: 7 - 14 days
Germination temp.: 20 - 25 °C
Sowing depth: 1½ - 2 cm
Planting distance: 15 - 20 cm
Distance between the rows: 30 - 40 cm
Plant postition: sunny - sheltered
Days till harvest: 60 - 90 days
To shorten the germination time of water spinach seeds, they can be soaked in water for 6 - 12 hours before sowing. Despite its name, water spinach does not have to be grown in water. However, it is a tropical plant that naturally grows in warm, humid climates. It tolerates heat very well but is sensitive to cold and drought. The seeds, seedlings, and mature plants should always be kept evenly moist. If the temperature drops below 10 °C, the plants will stop growing. Frost is extremely damaging and can kill the plants. The ideal growing temperature for water spinach is between 20 and 35 °C, with the highest temperatures promoting the fastest growth.
Start the seeds indoors from April onwards in pots filled with moist potting compost mixed with vermiculite. Maintain a constant germination temperature of 20 - 25 °C. Temperatures below 20 °C are unsuitable for successful germination. Place the pots in a propagator to keep both temperature and humidity as stable as possible. Prevent the temperature from dropping, especially at night. Keep the compost and seeds moist by using a plant mister. Water spinach seeds must never be allowed to dry out.
As water spinach is not frost-hardy, do not move the plants outdoors until all risk of night frost has passed and night temperatures remain above 0 °C. From mid-May onwards, or later if necessary, place the seedlings in an unheated greenhouse in a sunny position with well-drained soil. They can also be planted outdoors in a sunny, sheltered location with good drainage. Growth may be slow at first, but once daytime temperatures reach around 22 °C, the plants will grow vigorously. It is essential to keep the plants consistently moist, especially during dry weather. Keep the soil moist, but avoid waterlogging.
Like other leafy vegetables, water spinach has a high nitrogen requirement. Feed the plants weekly with a liquid fertiliser, such as tomato feed. Harvest the leaves and young stems. As water spinach belongs to the morning glory family, it naturally develops long climbing stems. Regular harvesting prevents excessive climbing and encourages the production of fresh leaves and tender shoots. Harvesting can begin from approximately 60 days after sowing. For the best flavour, eat the leaves and tender stems as fresh as possible. If necessary, wrap the leaves in damp kitchen paper and store them in the vegetable drawer of the refrigerator for 1 - 2 days. Water spinach is not suitable for freezing. As it is not winter-hardy in our climate, it is grown as an annual.
