What are the precautions for shading vegetable greenhouses in summer?

Growing vegetables in a greenhouse means covering with film to create a closed microclimate for cultivation, but in summer's high temperatures, the outside temperature is high, which raises the temperature inside the greenhouse as well, and you cannot ventilate freely either, because ventilating during the day actually lets the hot outside air in and makes the temperature even higher. So in summer many people have come up with methods to cool the greenhouse, but using these methods also requires attention to some issues; they should not be used blindly.

1. Shade net

The shade net chosen generally should not provide too much shade; a shading rate of about 40% is enough, not 50%, so that the vegetables' light requirements can still be met. Otherwise, if the vegetables receive too little light, their growth will be poor and their development will be affected. But a shade net with poor effectiveness is useless and also wastes money. So test it before buying.

2. Mud shading

Evenly covering the greenhouse surface with mud can block sunlight, but do not cover it too thickly. If the sun comes out in the morning and it feels a bit dark, then too much has been applied; it is best to rinse it with water, which will reduce it somewhat, then check again and if it has become brighter, that is fine. If it is still dark, rinse once more. Be careful not to make it dark in one patch and light in another, as this easily causes uneven vegetable growth.

3. Spraying cooling agents

At present, cooling agents are not widely used in actual production, so it is best to consult an expert before use and then decide whether to use them. Purchases should be made from legitimate manufacturers; do not buy randomly online or from irregular manufacturers. Before use, test on a small area first; if it is effective and has no side effects, it can be used on a large scale. If it has no effect, do not use it.

4. Coverage period

Generally, it is not necessary to cover with a shade net all day; just use it at noon when the sunlight is strongest and the weather is hottest, which can greatly reduce temperature and provide shade. But at other times when the light is not too strong, the vegetables can be allowed to receive light freely, which is beneficial to their growth and development. Roughly from 12 noon to 3 pm, coverage is needed, but each place can decide the time according to its climate.

The main shading methods for vegetables are shade nets, mud shading, and cooling agents, plus ventilation in the evening to lower the temperature. When using these methods, pay attention to the degree of shading, the time the vegetables receive light, and the different coverage times in different regions.