After constructing the seedbed in the ground, it is possible to raise seedlings all year round, especially for the vegetables cultivated in the off-season, the underground nursery can better show its advantages. Compared with the ground nursery method, it has the following two outstanding advantages: 1, cool in winter and cool in summer. Compared with ground seedbeds, the underground seedbeds have an average daily temperature of 1°C to 1.5°C and a ground temperature of about 2°C. In summer, the daily average temperature is 1°C to 1.5°C lower and the ground temperature is 2°C or so lower. 2, stable temperature. When carrying out underground nursery, the temperature and ground temperature of the seedbed are relatively stable and the temperature difference between day and night is small, so the seedlings can grow robustly and can cultivate strong seedlings. The method for making the underground seedbed is to dig a pit that is 5 meters wide, 25 meters long, and 1.25 meters deep in the place where the terrain is relatively high. The slope of the pit should be reduced to 30 degrees to increase the lighting surface. Increase to 60 degrees to save land. When digging, the 20-cm-thick soil on the surface is piled aside, and the rest of the soil is transported. After the pit is dug, a layer of organic fertilizer such as slag fertiliser, circumferried ring fertilizer, etc. is laid on the bottom of the pit, and then the topsoil will be excavated. Covered in organic fertilizer. The length, width and depth of the underground seedbed after completion are respectively 21.5m, 3.8m, and 1m. An escalator shall be dug in the east or west headland for easy access; dig around the ground at a distance of 20cm from the pit. A 30-cm-wide, 20-cm deep drainage ditch, shed feet in the outer edge of the drainage ditch, to prevent rainwater flowing into the pit; in the film above the north and south sides to open three skylights to facilitate ventilation. China Agricultural Network Editor