Dammit. I hate the metric system and temps given in celcius... Farenheit is so much easier on a predominately American site... 65-80 deg F is all good for lows and highs... 75 deg F is perfect if it can be maintained at all times... Below 65 deg F, and u r asking for stunted growth and "non-genetic" purpling, which is not a cool thing, as the cannabinoid and terpinoid production is slowed down, and/or stopped, and overall potency/quality goes down...