Temperature and humidity are the two most critical environmental factors in vertical farming. Proper control can increase yields by 20-40% while preventing most common plant diseases.
Understanding VPD (Vapor Pressure Deficit)
VPD measures the difference between moisture in the air and how much moisture the air can hold. It directly affects plant transpiration and nutrient uptake.
Optimal VPD Ranges: - Seedlings/Clones: 0.4-0.8 kPa - Vegetative Growth: 0.8-1.2 kPa - Flowering/Fruiting: 1.0-1.5 kPa
Low VPD = humid air = slow transpiration High VPD = dry air = plant stress
Temperature Guidelines by Growth Stage
Germination: 70-80°F (21-27°C) - Warmth speeds germination - Use heat mats if needed
Seedling Stage: 65-75°F (18-24°C) - Slightly cooler prevents stretching - Maintain consistent temps
Vegetative Growth: 70-85°F (21-29°C) - Warmer temps promote faster growth - Match to crop preferences
Flowering/Fruiting: 65-80°F (18-27°C) - Slightly cooler can improve quality - Night temps 5-10°F lower than day
Humidity Management
Target Ranges: - Seedlings: 65-70% RH - Vegetative: 50-70% RH - Flowering: 40-50% RH - Late flowering: 40-45% RH
Increasing Humidity: - Add humidifier - Place trays of water - Group plants together - Mist sparingly (risk of disease)
Decreasing Humidity: - Improve air circulation - Add dehumidifier - Increase ventilation - Raise temperature slightly
Equipment for Environmental Control
Essential: - Digital thermometer/hygrometer - Oscillating fans - Exhaust fan with speed controller
Recommended: - Environmental controller - Humidifier/dehumidifier - Portable AC or heater - CO2 monitor
Advanced: - Automated climate controller - Chiller for nutrient solution - CO2 supplementation system
Common Problems & Solutions
High Temperature + High Humidity: - Increase airflow and exhaust - Add dehumidifier - Reduce plant density
High Temperature + Low Humidity: - Add cooling or shade - Increase humidity carefully - Ensure adequate watering
Low Temperature + High Humidity: - Add heat source - Improve ventilation - Risk of mold - act quickly
Pro Tips
- •Monitor conditions at plant canopy level
- •Keep day/night temperature differential of 5-10°F
- •Use multiple fans for even air distribution
- •Log conditions to identify patterns
- •Adjust slowly - plants don't like sudden changes