1. Temperature requirements.

According to the specific requirements of temperature at each stage of the growth and development of vegetables grown in greenhouses, the manufacturers of vegetable greenhouse tubes generally have to conduct ventilation when the temperature in the greenhouses is higher than the temperature suitable for the growth of vegetables, to prevent the occurrence of chilling injury or freezing injury.

2. Amount of yard time required.

Greenhouse ventilation adhere to the principle of small to large, downwind direction, pay attention to adjust the local temperature difference in the greenhouse, relatively early ventilation at high temperature, vegetable greenhouse pipe wholesale, put a larger tuyere; In the low temperature relative late ventilation, put small tuyere. At the same time, prevent the cold wind from blowing directly on the vegetable plants, causing the vegetable leaves and young fruits to suffer from cold damage. The closing of the air outlet should be carried out step by step from large to small and from large to small.

3. Time requirements.

The aim of ventilation is to reduce the temperature and remove the moisture, add-, the time is usually controlled in the greenhouse when the temperature is too high, the relative humidity is large, the vegetable photosynthesis is accelerated. Ventilation is usually done one to two hoafter the curtain is lifted in the morning on a clear day.