Climate Control

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Climate control is temperature and humidity held where you want them, automatically. It is the difference between a room that performs the same in February and July and one that has a good winter and a bad summer – and for most growers it is a bigger lever than anything in a nutrient bottle. What you are actually controlling Temperature. Roughly 24-28°C lights on, a few degrees cooler lights off. Too hot and growth stalls; too cold and uptake slows. Humidity. High in propagation, moderate in veg, low in late flower. Around 70% for cuttings down to 40-45% in the last weeks. The gap between day and night. A large drop when the lights go off causes condensation on cold surfaces, and condensation in late flower means mould. Which problem do you have? Symptom Fix Too hot, lights on More extraction first – see extraction fans – then AC Too cold, lights off Heater on a thermostat Humidity too high in flower Dehumidifier Humidity too low in veg Humidifier Everything swings wildly A controller, not more equipment Extraction first, equipment second Most heat problems are ventilation problems. Before buying air conditioning, check the extraction is actually sized for the room and that the ducting is not throttling it – see ducting and fittings . A correctly sized fan solves a surprising number of temperature complaints for a fraction of the cost of AC. Controllers earn their money A heater on a plug timer heats on a schedule whether the room needs it or not. A heater on a thermostat heats when the room is cold. The same applies to fans, humidifiers and dehumidifiers – putting each on a sensor rather than a timer is usually the cheapest meaningful upgrade in a grow room. See grow room monitoring and humidity controllers . Sealed rooms and CO2 Once you are running air conditioning rather than extraction, the room is sealed and you can start enriching CO2 – but only then. Adding CO2 to a room you are venting is money out of the window, literally. See CO2 enrichment and full clima