I have been engaged in vegetable production technical guidance for many years and found that even farmers who have been engaged in vegetable production for many years often make mistakes in ventilation and ventilation skills in greenhouses, causing unnecessary losses to producers. Therefore, it is necessary to discuss with students' friends about the knowledge of ventilation and ventilation in greenhouse vegetable cultivation. In the winter and spring season, how can the sheds for growing vegetables be ventilated? It must be clear that the purpose of ventilating and ventilating greenhouses is to regulate the temperature, humidity, and carbon dioxide concentration in the shed and to discharge harmful gases. It is particularly important to properly and appropriately understand ventilation and ventilation technology. Farmers' friends should pay attention to the following principles and measures during actual production and operation. 1.Temperature: When the greenhouse is ventilated, the temperature in the greenhouse must be higher than the temperature suitable for the growth of the specific vegetable, so as to avoid cold or freezing damage to the vegetables caused by the low indoor temperature after the ventilation. Therefore, we must understand and grasp the temperature requirements of various stages of growth and development of various vegetables. 2. The amount of air release: When the greenhouse is ventilated, it must adhere to the principles of small to large, from small to large, and windward to ventilate. At the same time, we must pay attention to adjust the local temperature difference in the shed, relatively early ventilation in high temperature, put a larger tuyere; When the air outlet is closed, it should be from large to small, gradually from more to less. In addition, when ventilating and ventilating, cool air should be prevented from blowing directly into vegetable plants in the shed, causing the temperature to fluctuate, causing freezing damage to the leaves and young fruits of the vegetables. 3. Requirements for ventilation and ventilation time: The purpose of ventilation is to remove moisture and cool down, to meet the demand of carbon dioxide for photosynthesis of vegetables in greenhouses. Therefore, ventilation and ventilation time generally should be too high in the greenhouse, relatively high relative humidity, photosynthesis speed up when carried out, that is to say, 1-2 hours after the morning of the sunny curtain. In addition, after the application of watering fertilizer or spraying pesticides, due to increased humidity, ventilation should also be short-term. In cloudy snow weather, when the indoor relative humidity is high, carbon dioxide is depleted, and harmful gases are accumulated, short-time decommissioning of small winds should be carried out to meet the demand for carbon dioxide from vegetables. In addition, it can also reduce the consumption of nutrients in plants and improve the ability of plants to resist cold. In the event of a long period of overcasting, it is necessary to expose the covers outside the shed, and the amount of air to be blown off is small to prevent the light from becoming excessively strong and the transpiration will intensify, causing the vegetables to lose water and wilt. In short, during the winter and spring seasons, the knowledge of ventilation and ventilation of cultivating shed vegetables should be comprehensively applied and accumulated experience. It is necessary to consult and communicate with agricultural technicians often. Hunan Kangfutai Medical Devices Co., Ltd. , https://www.3kfut.com