How to manage greenhouse vegetables in cloudy foggy days
Density Meter,Excellence Density Meters,Powder Bulk Density Meter Dongguan Best Instrument Technology Co., Ltd , https://www.best-tester.com
July 02 04:26:33, 2025
How to Manage Greenhouse Vegetables on Foggy Days
When it comes to cloudy or foggy days, optimizing light conditions in greenhouses is crucial for maintaining productivity. There are four key strategies that can help improve the growth and yield of greenhouse vegetables:
First, consider using supplemental lighting. In greenhouses without natural sunlight, installing electric lights can significantly enhance light exposure. Turn on the lights in the morning and evening for 3–4 hours each, which, when combined with natural sunlight, can provide 15–18 hours of light per day. This method has been shown to increase yields by 10% to 40% and shorten the vegetative growth period by 17–21 days.
Second, use purple film. Unlike white film, which only allows 57% of light through, purple film lets in up to 88% of the spectrum, including beneficial ultraviolet light. UV light helps reduce disease, control plant growth, and promote better nutrient accumulation. Additionally, the room temperature under purple film is typically 2–3°C higher than under green film during winter.
Third, install a light curtain on the back wall of the greenhouse. This can improve light intensity in the rear areas where plants may otherwise receive less light. At night, the heat stored in the wall can be gradually released, helping to maintain a warmer environment and prevent freezing damage during cold nights.
Fourth, if none of the above options are available, maximize natural light exposure as much as possible. Alongside this, two additional practices are important: applying foliar sprays to strengthen plants against cold stress. For example, spraying calcium nitrate can help compensate for weak root absorption in low temperatures. Mixing rice vinegar with white sugar and superphosphate can improve leaf hardness and sugar content, enhancing cold resistance. Also, avoid over-picking vegetables like zucchini and tomatoes to reduce unnecessary nutrient consumption. Focus on preserving the plant's energy and avoid excessive use of growth hormones that may weaken cold tolerance.
Additionally, practice shallow cultivation to break up soil cracks, which helps retain heat and protect against frost. Finally, consider using carbon dioxide (COâ‚‚) fertilizers. COâ‚‚ enhances photosynthesis, especially during periods of high light intensity. During the day, open vents to allow external COâ‚‚ in, and at night, use generators or granular fertilizers to release COâ‚‚ artificially. This not only improves plant health but also boosts overall yield.
By implementing these techniques, growers can effectively manage greenhouse vegetables even on the cloudiest days.