When is the coldest time in the greenhouse in winter?

The coldest time in the greenhouse in winter is around 4 am.

In winter, the climate is cold, the temperature is low, and there are often strong winds to cool down. Vegetables have shallow roots and poor frost resistance, which may lead to yield reduction or grain failure, and vegetables in greenhouse are vulnerable to low temperature damage. The lowest temperature in the greenhouse is around 4: 00 in the morning. During the day, it relies on sunlight to store heat, and gradually dissipates heat in the first half of the night.

Related information:

1, the greenhouse should be ventilated in winter, and the humidity inside and outside the greenhouse is quite different at noon, so the humidity is easy to be discharged. Moreover, ventilation and dehumidification should ensure the temperature requirements and extend the ventilation time as much as possible.

2. Clean the sand and dust on the greenhouse film on sunny days. Don't water or spray pesticides on cloudy days. When the temperature drops, on cloudy days, vegetables will turn yellow because of insufficient light. In order to increase the light, we should open the straw curtain to transmit light every day, and hang a reflective film on the wall near the north in the greenhouse to let the vegetables receive scattered light to maintain the formation of chlorophyll.

3. Watering greenhouse vegetables in winter, usually on sunny days, to avoid watering on cloudy days; Water before noon and don't water after noon; When watering, irrigate with small water to avoid flooding; When the water temperature is low in winter, it should be preheated in the shed first, and then watered when the water temperature is close to the ground temperature; When watering, pour dark water and avoid bright water.

4. In rainy and snowy weather, the thermal insulation quilt and grass quilt should be covered with a layer of shed film to prevent the quilt and grass from getting wet by rain and snow. Covering with plastic film can effectively raise the temperature, generally raising the ground temperature at 10 cm by 2℃ ~ 3℃ on average. At the same time, because the plastic film is airtight, it can reduce the evaporation and irrigation times of groundwater, thus achieving the purpose of reducing the air humidity in the shed.