How to prevent vegetables from freezing in greenhouse in winter

Freezing methods of vegetables in greenhouse in winter;

1. The management of fertilizer and water needs to be strengthened.

Before and during low-temperature freezing injury, crops should stop using nitrogen fertilizer to prevent plants from being too soft and cold-resistant and chemical fertilizers from killing seedlings. 0.3-0.5% potassium dihydrogen phosphate and 400-500 times of plant antifreeze can be sprayed. Thin manure water is poured in the shed, so the soil is not easy to freeze, and the purpose of protecting seedlings from the cold is achieved.

Two. Attention should be paid to strengthening coverage.

Tie a small arch shed in the greenhouse, use thin bamboo poles as the arch frame, and cover the film at night with grass; Covering the shed with plastic film can increase the temperature and keep moisture. Using plastic film as apron at the bottom of shed can obviously reduce the invasion of cold air at the bottom; At the same time, pay attention to plug the gap in the shed to minimize the gap heat dissipation. In the north of the greenhouse, crop straws are piled up to form a wind barrier to protect against wind and cold.

1. Close planting in low ridges and proper deep planting.

In winter, the northwest wind often blows, and shallow ditches with a depth of 10 ~ 13 cm can be opened in the border to avoid the wind and keep warm. According to the measurement, the surface temperature of the soil in the ditch is 65438 0 ~ 2℃ higher than that in the flat land. In winter, the planting density of vegetables can be larger and the spacing between vegetables can be smaller, which is not only beneficial to the accumulation of respiratory heat of the group, but also can reduce the invasion of cold air and improve the air temperature and ground temperature between plants. In winter, vegetables should be planted deeply, and the roots vulnerable to freezing should be buried in the soil to avoid wind blowing and reduce freezing damage. Conducive to the protection of crops.

2. Artificial covering of antifreeze

Before winter, use fallen leaves, loose hair or crop stalks to spread on vegetable fields as long-term mulch in winter, and remove them when the weather gets warmer in spring. These mulches can not only reduce the wind speed between vegetable plants on the ground, but also block the loss of heat on the ground, and have little effect on light. Pay attention to the fact that the plastic film should not be too thick, otherwise it will adversely affect the photosynthesis of vegetables. When the cold wave comes, straw and wheat straw should be used for temporary covering, which can be thicker, and should be removed in time after the cold wave.

3. Manage fertilizer and water well

After winter vegetables are watered in time to prevent freezing, water should be applied reasonably to promote early development. After winter, the amount of nitrogen fertilizer should be controlled to prevent excessive growth. Before and after the cold wave invasion 1 ~ 2 days, when the weather turns warmer and the soil thaws, watering or applying dilute human excrement and urine in time can prevent the ground temperature from dropping too low and promote the crops to resume growth in time.