Key Technical Points for Growing Water Spinach in Plastic Greenhouses

1. Variety selection    Varieties suitable for planting in our province include Dajihuang, Daguqing, Jianye, Siweng, Dajiqing, etc.

2. Sowing period    Greenhouse cultivation can basically produce and supply year-round. In order to obtain higher economic benefits, sowing should be arranged from October to December, with marketing from December to March of the following year.

3. Land preparation and fertilization    Water spinach grows quickly and has strong branching ability, so it requires more fertilizer and water. It is advisable to apply sufficient base fertilizer. Generally, 1500-2000 kg of decomposed organic fertilizer and 100 kg of plant ash are applied per mu, fully mixed with the soil, and beds 20 cm high and 130-150 cm wide (including ditches) are made.

4. Seed soaking and germination    The seed coat of water spinach is thick and hard. If sown directly, germination will be slow due to low temperature. If there is prolonged low-temperature and rainy weather, the seeds may rot. Therefore, germination should be promoted. The seeds can be soaked in warm water at about 30°C for 18-20 hours, then wrapped in gauze and placed in a germination box at 30°C to promote germination. When 50%-60% of the seeds have broken white, sowing can be carried out.

5. Sowing    Water spinach can be broadcast or drilled. The seeding rate is 1.5-2.0 kg per mu. After broadcasting, cover with fine soil about 1 cm thick. For drilling, draw a shallow trench 2-3 cm deep across the bed surface, with a row spacing of 15 cm, then evenly scatter the seeds in the trench, cover with fine soil, then cover the bed surface with a shade net, and then water. After emergence, the shade net can be removed.

6. Management in the greenhouse

1. Temperature and humidity management    When water spinach is cultivated in greenhouses in winter, the temperature is low, the humidity is high, and the continuous low-temperature and rainy weather lasts a long time, which is extremely unfavorable to the growth of water spinach, which prefers warmth. Therefore, heat preservation and cold protection are the key to off-season cultivation. After sowing, the greenhouse should be sealed in time to ensure that the temperature inside the greenhouse is higher than 10°C; otherwise, freezing damage may occur. At the same time, when there is sufficient sunlight and the temperature is relatively high, ventilation should be strengthened to remove moisture, and try to avoid the temperature inside the greenhouse being higher than 35°C, to prevent plant diseases and maintain vigorous plant growth and increase yield. The relative air humidity inside the greenhouse may reach 100% under relatively high humidity and rainy days. At this time, the films at both ends or around the greenhouse must be opened in time for ventilation.

2. Fertilizer and water management    Water spinach is a crop harvested multiple times. Therefore, in addition to applying sufficient base fertilizer, multiple topdressings by stages must be carried out to achieve high yield. At the seedling stage, 10%-15% dilute human manure and urine can be used for drenching, with an application rate of 1000-1500 kg per mu. When the seedlings have 3-4 true leaves, 15-20 kg of compound fertilizer and 2-4 kg of urea can be mixed and applied. During the harvest period, 5-8 kg of compound fertilizer (per mu) should be applied as topdressing after each harvest. Water spinach has a relatively large water requirement, so it should be watered frequently to keep the soil surface moist.

3. Pest and disease control    The main diseases are damping-off and stem rot at the seedling stage, which are caused by low temperature and excessive relative humidity. Reducing humidity can alleviate the occurrence of the diseases. They can be controlled by spraying 700 times dilution of Ridomil or 800 times dilution of Kameitong.

The main insect pests are mites and red spiders, which can be controlled by spraying 1000 times dilution of Comite or 1500 times dilution of Cascade.

4. Harvesting    Generally, 35-45 days after sowing, when the water spinach plants have grown to a height of 35 cm, they should be harvested in time.