How to keep warm in spring and autumn greenhouses?

In the early stage of vegetable growth, that is, the early stage of flowering and fruiting, the daytime temperature should be controlled at around 23℃, and a thermometer should be hung in the middle to see the average temperature. The temperature required in the full fruit stage is 28 ~ 30℃, which refers to the fruit expansion temperature, so the thermometer must be hung at the position of the first ear of fruit, about 30 cm from the ground. If the temperature is lower than 10℃, which is not conducive to the growth of vegetables, heat preservation measures should be taken in time. The following specific measures can be taken:

First, increase the air permeability of the shed film. Using high-light-transmission non-dripping film and cleaning the dust and snow on the film in time can enhance the light and raise the temperature of the shed.

Second, improve the thermal insulation of the straw curtain. The straw curtain on the greenhouse should be strong. In order to improve the thermal insulation performance and prevent rain and snow from wetting the straw curtain in late winter, a layer of ordinary agricultural film or old film can be covered on the straw curtain.

Third, increase the thermal insulation of the back wall. When building the back wall, you can stick a layer of brick on the earth wall, or you can build a hollow thermal insulation wall, which is filled with straw or polystyrene foam board. Firewalls can be built directly in cold areas to facilitate heating up.

Fourth, dig a cold ditch outside the shed. Dig a cold ditch with a depth of 40-60 cm and a depth of 40-50 cm outside the greenhouse and fill it with heat preservation materials such as sawdust, weeds, horse manure and straw. , and cover the trench with soil to achieve thermal insulation effect. When the cold current approaches, adding straw curtains or corn stalks around the shed at night can increase the shed temperature by 2-3 degrees Celsius.

5. Dig back the ridge and ditch along the planting line 30-35cm in the shed, with the ditch depth of 45cm and width of 50cm. Spread rice husk or wheat bran at the bottom of the ditch about 5cm, and drive 1 stake every 50cm away from the side wall of the ditch, and fill the space between the fixed stake and the side wall with corn stalks. The top of the ditch is covered with 60-70 cm long bundled corn stalks with a diameter of 10 cm, and the ditch is covered with soil. Except the working path, the rest of the ground is covered with plastic film, and the whole greenhouse forms an "S"-shaped ditch with an opening at a slightly higher place, which can be opened or closed in time to control the ground temperature.

Temporary heating measures can be set for intransitive verbs. 2-3 heaters with power of 1600-2500 W can be set temporarily in the shed, and the outlet direction of the heaters should not be directly facing the factory building.

Seven, hanging reflective curtain in the greenhouse, hanging plastic film or tin foil coated with metal layer on the back wall of the greenhouse, hanging 1 meter every 2-3 meters, reducing the absorption of heat energy by the wall and raising the temperature in the greenhouse by 2-3 degrees Celsius.