Light transmittance is one of the most critical performance indicators for modern commercial greenhouses, directly affecting crop photosynthetic efficiency, growth quality, and final yield. In line with GB/T 4455-2019 national standards and ASTM D 1003-13 international optical testing specifications, professional greenhouses adopt graded light transmittance standards for different covering materials and crop types to avoid insufficient illumination or intense radiation damage to plants.
Light Transmittance Standards for Greenhouse Covering Materials
Common greenhouse covering materials have fixed industry-recognized transmittance baselines. New agricultural plastic films feature an original light transmittance of 80% to 90%. Due to natural aging and surface dust accumulation during long-term use, the minimum qualified transmittance for operational plastic films is standardized at ≥85%. As a high-end horticultural covering material, greenhouse glass delivers superior optical stability, with a mandatory standard transmittance of ≥91.5%, providing sufficient photosynthetically active radiation for high-value crops. Traditional solar greenhouses follow a basic standard of ≥70% transmittance to meet daily growth needs of conventional crops.
Crop-Tailored Light Transmission Requirements
Different crops require customized light transmittance conditions for optimal growth. High-light-loving crops such as tomatoes, peppers, and ornamental flowers need a light transmittance above 90% to support vigorous growth and high-quality fruiting. Shade-tolerant leafy vegetables adapt well to a moderate transmittance of around 85%.
Strong direct sunlight in hot summer poses a major threat to greenhouse crops, easily forming indoor light hotspots that cause leaf burn and heat stress. Yuhua greenhouse diffused glass effectively solves this industry pain point. The professional textured glass converts harsh direct sunlight into soft, evenly distributed diffused light, eliminating local overexposure and light spots. It completely avoids crop leaf burn, balances indoor light and temperature distribution, and significantly optimizes the greenhouse light environment. This improves crop light utilization efficiency and enhances high-temperature stress resistance, ensuring stable growth and continuous yields in summer.
Key Influencing Factors & Scientific Maintenance Methods
Material haze and daily maintenance are core factors affecting long-term light transmittance. High-haze covering materials greatly reduce effective light transmission, so low-haze, high-transmittance materials are preferred for commercial greenhouses. Agricultural monitoring data shows that uncleaned dust and scale can reduce greenhouse light transmittance by 10% to 20%, seriously restricting crop photosynthesis.
Scientific daily maintenance is essential to sustain stable light performance. Plastic films require regular cleaning with soft brushes or high-pressure water, while stubborn stains need neutral detergent to prevent surface scratches. Greenhouse glass and hollow boards need deep cleaning every 2 to 3 months to clear silt and inspect for cracks. Damaged materials should be repaired or replaced timely to avoid light loss and structural risks.
Seasonal maintenance further stabilizes light transmission performance. Spring focuses on cleaning, disinfection and film frame reinforcement; summer emphasizes sunshade adjustment and drainage system cleaning; winter maintenance centers on protecting covering materials to prevent cold and wind damage. In summary, the minimum baseline transmittance of all greenhouse covering materials should not be lower than 70%, and scientific adjustment and maintenance can maximize planting benefits.Greenhouse light transmittance needs dynamic adjustment according to crop photophilic characteristics.
