My grow room tends to be in the mid 60's. I have a small oscillating fan to blow the air around. Since it's been getting colder and colder here, I just started using a small portable heater-fan to lightly blow warm air on my plant. My question is; Does it matter if I use cold or warm air to circulate air flow?
the mid 60's are a little cold yea but your lights should produce enough heat to warm up the room - I have to bring cold air from outside in the winter or I have to run my ac all the time the air that is being circulated can be whatever temp as long, if its really hot or cold then you shouldnt let it blow onto the plants directly but just into the room but the circulating air dont mattter much as long as the room temps are within acceptable limits - IMO 70-75 deg F, maybe hotter if you are using co2 you could take a heater and a fan and have the heater blow into the fan and then into the room but just not directly onto the plants