Detailed Explanation of the Key Technical Points for Proper Ventilation in Greenhouses

In a greenhouse, do not ventilate within one hour after pulling open the straw curtains in the morning.

This is because after the straw curtains are put down at night, the vegetables in the greenhouse stop photosynthesis and only carry out respiration, releasing a large amount of carbon dioxide. At the same time, microorganisms in the soil also release carbon dioxide as they break down organic matter. After a whole night, the carbon dioxide level accumulated in the greenhouse rises noticeably, far higher than the carbon dioxide content in the outside atmosphere. So the next morning, do not ventilate during the first hour after the straw curtains are pulled open. After the vegetables receive light, they begin photosynthesis, fully absorbing the carbon dioxide in the greenhouse and converting it into organic matter stored in the fruit. Within a single day, 70%-80% of the photosynthetic products are synthesized in the morning. During this one hour before ventilation, the organic matter accumulated by the plants through photosynthesis will be several times the usual amount, greatly increasing vegetable yields.

Therefore, when the sun rises in the morning, pull open the straw curtains, wait one hour, then ventilate slightly for 7-8 minutes, then stop ventilating. After the temperature inside the greenhouse rises to a certain level, ventilate again according to the actual situation. The main purposes of slight ventilation are, first, to lower the temperature; second, to remove moisture; and third, to expel harmful gases. Proper ventilation management is an effective method for high greenhouse yields and can greatly increase the yields of vegetables and melons. Liu Haichuan