Why climate control defines greenhouse success
Greenhouses modify the plant environment beyond what field conditions provide. Temperature, relative humidity, light intensity, and CO₂ concentration interact to determine growth rate, flowering time, and disease pressure. Unlike open-field production, every environmental variable is manageable — but only when sensors, actuators, and crop physiology are understood together.
Temperature management
Most greenhouse crops perform best within a day/night differential (DIF) that influences stem elongation. Warm days with cooler nights often produce shorter, sturdier plants. Ventilation through roof vents and side walls removes excess heat; shade cloth reduces solar gain in summer. Heating systems (hot water pipes, unit heaters) maintain minimum night temperatures during cold seasons.
Humidity and disease
- High humidity (>85%) favors powdery mildew, botrytis, and condensation on leaves.
- Low humidity increases transpiration stress and tip burn in sensitive crops.
- VPD (vapor pressure deficit) integrates temperature and humidity — target VPD ranges guide irrigation and ventilation decisions.
Light and CO₂ supplementation
Supplemental lighting (LED or HPS) extends photoperiod and increases daily light integral (DLI) in winter. CO₂ enrichment to 800–1000 ppm can raise photosynthesis when vents are closed, but becomes wasteful if air exchange is high.
Key takeaway: Climate control is not about holding one fixed temperature — it is about matching the greenhouse environment to crop developmental stage and local weather.