How to manage greenhouse vegetables in cloudy foggy days
July 02 04:07:49, 2025
How to Manage Greenhouse Vegetables on Foggy Days
When it comes to cloudy or foggy days, maintaining sufficient light in greenhouses is essential for maximizing crop production. There are several effective strategies that can be implemented to ensure optimal growth:
First, consider using supplemental lighting. In greenhouses without natural sunlight, installing electric lights can significantly improve the light conditions. It’s recommended to turn on the lights in the morning and evening, extending the total light exposure to 15–18 hours per day. This method has been shown to increase yields by 10% to 40% and shorten the vegetative growth period by up to 21 days.
Second, using purple film can enhance plant development. Purple film allows more ultraviolet light to pass through compared to white film, which helps control diseases, regulate plant growth, and promote better nutrient accumulation. The temperature inside the greenhouse with purple film is typically 2–3°C higher than with green film during winter.
Third, install a light curtain on the back wall of the greenhouse, especially before and after the winter solstice. This not only improves light intensity for the rear plants but also helps retain heat from the walls, keeping the temperature stable during the night and preventing frost damage.
Fourth, if other options are not available, try to maximize natural light. In addition to artificial lighting, there are two key points to focus on: foliar feeding and proper management practices. During cold periods, spraying leaves with micro-fertilizers like calcium nitrate can help compensate for weak root absorption. A mixture of rice vinegar, white sugar, and superphosphate can improve leaf hardness and cold resistance. Avoid using excessive growth hormones, as they may reduce the plant's ability to withstand low temperatures.
In terms of management, it’s important to harvest vegetables early and avoid over-picking, especially for crops like zucchini and tomatoes. Prioritize root health and avoid overexerting the plants. Shallow cultivation can help prevent soil cracking and reduce heat loss at night.
Finally, consider using carbon dioxide (COâ‚‚) fertilization. COâ‚‚ is crucial for photosynthesis, especially during winter when plants may suffer from carbon starvation. Using COâ‚‚ generators or granular fertilizers can boost yield and improve plant resilience. Industrial sulfuric acid reacting with ammonium bicarbonate is one common method, while organic fertilizers can naturally release COâ‚‚ as they decompose.
By implementing these techniques, greenhouse growers can maintain healthy and productive vegetable crops even during foggy or cloudy conditions.