I've a small heated greenhouse with a few veg. and bonsai plants taken inside for the winter. Due to the weather it's been shut up quite tightly over the past week or so. I always keep the greenhouse well ventilated in summer but just wondered about winter. When its not freezing should I open a window or would the plants be happier being kept a bit warmer with everything shut up.
I recall reading an article about the importance of greenhouse ventilation but can't find it now.