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How to shade the greenhouse vegetable greenhouses in the summer (on)
In summer, vegetable farmers frequently use shading techniques to lower the temperature inside greenhouses and protect crops from excessive heat. In practice, farmers employ a variety of shading methods—some opt for black and silver shade nets to cool down the environment, while others apply mud or ink on the plastic films. These different approaches can significantly affect the cooling efficiency and crop health. The author explores the advantages and disadvantages of current shading methods used in greenhouses and highlights important considerations when implementing shading for cooling.
Choosing shade nets scientifically is crucial. The primary purpose of shade nets is to block sunlight and reduce greenhouse temperatures. Covering with shade nets is an essential practice during hot seasons to ensure optimal vegetable growth. However, using the wrong type of net can lead to weak, leggy plants and poor fruit setting. Therefore, it's vital to select shade nets wisely based on the specific needs of the crops.
It’s important not to judge the quality of shade nets solely by their color. On the market, black and silver-gray nets are commonly available. Black nets provide high shading and quick cooling, making them suitable for short-term use in areas requiring strict temperature control. Silver-gray nets, on the other hand, have a lower shading rate and are ideal for high-light crops that need long-term coverage. The color of the net is added during manufacturing, so it doesn’t determine quality. Different crops require different light conditions. For example, tomatoes are high-light crops; they thrive with 11–13 hours of sunlight daily, which helps them grow strong and flower earlier. While light duration is less critical, light intensity directly impacts yield and quality. Insufficient light can cause weak growth, poor flowering, and reduced fruit set. Tomatoes reach their light saturation point at around 70,000 lux, and their compensation point ranges between 30,000 and 3.5 million lux. During midday in summer, light intensity often reaches 90,000–100,000 lux. A black net with up to 70% shading may not meet the tomato’s light requirements, potentially causing growth issues. In contrast, silver-gray nets with 40–45% shading allow 40,000–50,000 lux of light, which supports healthy tomato growth. Thus, silver-gray nets are generally the best choice for tomatoes.
When purchasing shade nets, it's also important to distinguish between materials. There are two main types available: high-density polyethylene (HDPE) and recycled plastic-based nets. HDPE nets are more durable, resistant to aging, and can last up to four years. Recycled nets, however, tend to have a rough texture, unpleasant odors, and a shorter lifespan, often lasting only one season. Farmers should be cautious and check the material quality before buying.
Another thing to watch out for is how shade nets are sold. Some vendors sell them by area, while others by weight. Farmers should not rely solely on weight as an indicator of quality. It's better to compare both the material density and the overall quality to avoid being misled by low-quality products that appear heavy but are actually inferior. Careful selection ensures that the shade nets provide effective cooling without compromising crop health.