What time is the coldest time in the greenhouse in winter?
The coldest time in the greenhouse in winter is around four in the morning.
The climate in winter is cold, the temperature is low, and strong winds often occur. Vegetables have shallow root systems and poor frost resistance, which can range from reduced yields to no harvest. Greenhouse vegetables are susceptible to low temperature damage. The greenhouse temperature is the lowest around 4 a.m., and it accumulates heat due to solar radiation during the day, and gradually dissipates heat in the first half of the night.
Related information:
1. During the winter, the greenhouse should be ventilated and have more light. The humidity inside and outside the greenhouse differs greatly at noon, and moisture is easily discharged. Moreover, ventilation and moisture removal must ensure the temperature requirements and at the same time extend the ventilation time as much as possible.
2. Clean the sand and dust on the greenhouse film on sunny days. Do not water or spray pesticides on cloudy days. During cooling and cloudy days, due to the lack of light, the dark environment for days will cause the vegetables to turn yellow. To increase the light, the straw curtain should be opened every day to let the light in, and a reflective film should be hung on the north wall of the greenhouse to allow the vegetables to grow. Receive scattered light to maintain the formation of chlorophyll.
3. When watering greenhouse vegetables in winter, generally water on sunny days and avoid watering on cloudy days. Water before noon and not after noon. When watering, water should be small and fine to avoid watering. Flood irrigation with heavy water; in winter, the water temperature is low. When watering, preheat it in the shed first and wait until the water temperature is close to the ground temperature before watering; when watering, pour dark water and avoid pouring open water.
4. In rainy and snowy weather, a layer of shed film should be added to the insulation quilt and thatch to prevent rain and snow from getting the quilt and thatch wet. Covering with mulch can effectively increase the temperature. Generally, it can increase the ground temperature at 10 cm by an average of 2°C to 3°C. At the same time, because the mulch film is not breathable, it can reduce the evaporation of ground water and the number of irrigations, thereby achieving the purpose of reducing the air humidity in the shed.