In the winter and spring seasons, it sometimes happens that the temperature inside the greenhouse is lower than outside the greenhouse. This phenomenon is called inversion and often occurs around midnight. Vegetable seedlings are very sensitive to this, and a little care can lead to frost damage.
There are two main reasons for the inversion of greenhouses: First, in a sunny day, the temperature in the greenhouse rises rapidly; at night, it emits heat through long-wave radiation through the cover; second, the temperature of the leaves is higher than the temperature of the plants. It also produces heat radiation.
To prevent greenhouse inversion, the following measures should be taken:
One is sorghum cultivation, covered with plastic film. For seedlings such as tomatoes, eggplants, and peppers that are transplanted in winter, the soil in the shed should be ridged and cultivated into sorghum before planting, and then covered with a plastic film. Doing so can lower the groundwater level, slow the loss of heat in the evening, and insulate and keep warm. It should be noted that the mulch must be tightly sealed around to prevent the intrusion of cold air.
The second is sheds and multi-layer coverings. After the vegetable seedlings are transplanted and survived, additional sheds should be added to the sheds to cover them in multiple layers. This can effectively increase the temperature inside the sheds.
The third is to add curtains and cover textiles. Since the gates of greenhouses often open, affecting the effect of thermal insulation, curtains or old membranes are used as curtains outside the gates to prevent cold air from entering. In addition, weeds and other grass textiles can be placed around the shed to reduce the heat emitted from the shed.
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