Its what they get used to, I think. And its for a few hours at most then its 20C again!
Nice work! Congrats.
You can always install a small heater just in case...
If you have no other heat source, drag your gas grill into the GH...
Two pieces of advice that you didn't ask for 1. your concrete floor will get VERY slick and you need to keep it
very clean or "you'll break your neck" as all mothers say
2. Get a gas generator for a backup system in case of
power failures. Your greenhouse is not so large that you'd have to have a large generator so less expense.
David, your summer experience??? Thanks