Temperature and humidity control in a vegetable greenhouse are critical to crop growth, yield and quality.
Temperature control requirements
Daytime temperature: The suitable temperature range for most vegetables is 20°C to 30°C. For example:
- Tomatoes: 22°C to 28°C
- Cucumbers: 25°C to 30°C
- Leafy vegetables (such as lettuce, spinach): 15°C to 25°C
Nighttime temperature: The temperature at night should be slightly lower, usually between 15°C and 20°C, to promote plant respiration and nutrient accumulation.
Temperature difference control: The temperature difference between day and night should be kept between 5°C and 10°C. Too much or too little will affect growth.
Humidity control requirements
Relative humidity: The suitable relative humidity range for most vegetables is 60% to 80%. For example:
- Tomatoes: 60% to 70%
- Cucumbers: 70% to 80%
- Leafy vegetables: 60% to 75%
Effects of excessive humidity: May cause diseases (such as mold, gray mold) and weaken transpiration.
Effects of low humidity: May cause excessive transpiration, plant dehydration, and affect growth.
Coordinated control of temperature and humidity
Ventilation: Regulate temperature and humidity through natural or mechanical ventilation to prevent excessive humidity and temperature fluctuations.
- Cooling system: Such as wet curtain-fan system or spray system, which can reduce temperature and increase humidity at the same time.
- Heating system: Use heating equipment (such as hot air blower, floor heating) to maintain a suitable temperature in winter or at night.
- Dehumidification equipment: Such as dehumidifier or condensation dehumidification system, used to reduce humidity when humidity is too high.
Requirements for different growth stages
- Seedling stage: Higher temperature and humidity (such as 25°C to 28°C, humidity 70% to 80%) are required to promote seed germination and seedling growth.
- Growing period: Temperature and humidity can be appropriately reduced, but still need to be kept within the appropriate range.
- Flowering and fruiting period: Temperature and humidity need to be strictly controlled to avoid excessive humidity leading to poor pollination or disease.