Keeping the temperature of your grow room within the correct range will optimise your plant growth. The ideal air temperature range is between 18C - 25C (65F - 77F) with an average temperature over the course of a 24 hour period being between 21C - 23C (70F - 75F). Check out our blog for Top Tips for Growing in Cold Conditions. A grow room heater will help your grow going sweetly during the winter months. For perfect grow temperatures and humidity levels, check out the Opticlimate Full Climate Control Units which keep your grow room environment exactly right.