Thanks for all the tips.

Just to clarify: My grow is insulated but the shed is too big to insulate so I just want to heat the grow. Even if I did insulate the shed, air venting would let most heat escape anyway. This is of course the same with the grow but it's so small that keeping it warm shouldn't be a very big expense despite losing some heat to air replacement.
So I need a very small heater that will fit in the grow. Right now I'm leaning towards the oil filled radiator that Stinky suggested. I just wish there was something gas powered since it would be so much cheaper to run.

Question: how often do I need to replace the air during dark hours? Can I just leave the vents open but the fan off? This would retain the heat much better than actively venting. I can of course still keep moving the air inside the grow itself with a small pc fan.
Bulster Reviewed by Bulster on . Help: Heating a very small grow I am doing a super small grow in an outdoor shed for my own medicinal use. I just started flowering and it's getting pretty darn cold out there already. How can I heat this tiny space without having to heat my whole shed? The grow is only 1.5 by 2 feet but I have about 6 feet vertical clearance. I have thought about : - Super small propane heater... but how would that work? and what about humidity? - Heating blanket or 'propagation mat'... but will 40 watts of heating power make any Rating: 5