My neighbour has offered me the use of her unheated greenhouse to help protect a large pot of outdoor succulents which I know are not fully hardy here in Vancouver. Being new to greenhouses I need some advice about ventilation and frost protectionThe greenhouse is ~25 yrs old, about 6' x 10' x 8' high, traditional glass with a metal frame and is located on her patio. The location has moderate sun exposure since all the nearby trees are deciduous and it isn't particularly windy because there are fence and building walls nearby on 2 sides. It doesn't have electricity, though I could probably run an extension cord if necessaryAm I right that leaving the door and window closed will cause things to get mildew? Or will there be enough leakage through the old window joints? Will opening the door for a short time once a week be enough ventilation?I think my plants would do best at about 35 to 40 degrees F, but could probably take a bit of frost. Is there anything I can do short of installing a permanent heater to keep the temperature from dropping too much on really cold nights?
Might work better to leave them out all the time except for the week or so when it will be too cold - and during that time just put them in your garage or other intermediate area. They definitely won't want to sit around in a close, damp atmosphere, and I can't seen heating a greenhouse even this small for the sake of one pot of plants. Otherwise, find out how well the vents work, how damp it gets in there etc. from her. You could be able to keep frost off by using a heater that comes on when it is just above freezing, although the commercial type I have been around would cost a lot more than the pot of plants is likely to be worth - and might be much more effective at quickly raising the temperature in a space than a less powerful kind.
