Climate & ventilation
Maintain greenhouse climate balance year-round
Use these benchmarks, sizing rules, and automation tips to keep plants in their comfort zone regardless of the weather outside.
Ideal environmental targets
| Metric | Recommended range |
|---|---|
| Air temperature | 68–75°F (20–24°C) day / 55–65°F (13–18°C) night |
| Relative humidity | 50–70% depending on crop stage |
| CO₂ concentration | 400–800 ppm |
| Airflow velocity | 50–100 ft/min across canopy |
Track these values daily and note deviations in your greenhouse log so you can correlate plant responses with environmental changes.
Heating solutions for every structure
Electric unit heaters & radiant mats
Simple to install, 100% efficient at point of use. Best for small structures or zone heating propagation benches. Pair with dedicated circuits and thermostats.
Propane or natural gas heaters
Cost-effective for larger greenhouses. Use sealed combustion models and vent exhaust outdoors to protect plants from ethylene.
Hydronic or hot-water systems
Provide even heat and can integrate with radiant floors or root-zone tubing. Require regular pump and boiler maintenance.
Combine heating data with the heating cost calculator to budget fuel or electricity usage across the season.
Humidity management plan
- • Water early in the day so foliage dries before nightfall.
- • Space plants and prune dense canopies to improve air movement.
- • Use heat-and-vent cycles (also called drop-and-dry) to reduce condensation after sunset.
- • Keep floors free of standing water and install drains or sump pumps if needed.
Design ventilation that keeps air moving
Natural ventilation
Roof vents exhaust hot air while side vents or roll-up sides draw in cooler air. Design vent area to equal 15–20% of floor space.
Mechanical ventilation
Use exhaust fans with matching intake shutters. Calculate fan capacity (CFM) using greenhouse volume × desired air change rate (e.g., one change per minute in summer).
Integrated controls
Link vents, fans, heaters, and shade to a single controller or smart hub for automated responses to temperature and humidity thresholds.
Monitoring and automation essentials
- • Place sensors at canopy height and away from direct sunlight to prevent skewed readings.
- • Use data loggers or connected monitors to track trends and diagnose issues.
- • Set alerts for temperature spikes >85°F (29°C) or dips below crop minimums.
- • Calibrate sensors twice per year and after any major weather event.
Implementation roadmap
- Audit current heating, cooling, and ventilation capacity; document maintenance history.
- Install or calibrate sensors and connect them to your preferred monitoring platform.
- Develop seasonal setpoints (winter, shoulder season, summer) for automation controllers.
- Schedule quarterly maintenance for fans, vents, heaters, and evaporative systems.
Frequently Asked Questions
How much ventilation does my greenhouse need?
Aim for vent openings equal to at least 15% of floor area. For mechanical systems, size fans so you can exchange the greenhouse air volume once per minute during peak season.
What humidity level is ideal?
Most crops perform best between 50–70% RH. Drop humidity to 50–55% during flowering to reduce disease risk, and allow slightly higher levels for propagation.
Can I automate climate control?
Yes. Use integrated controllers or IoT sensors to automate vents, fans, heaters, and shade cloth. Automation provides faster adjustments and better consistency than manual changes.