Well, all I can say is:GOOD LUCK finding a cheap way to heat your greenhouse in the winter. I am in N. East Tex. and last winter was very cold...even for Texas. Even got down to 14 degrees. Yes, I do have an electric heater, but its not enough at times. My bill for the green house was running me about $100.00 per month. This Winter, when it gets really cold, ALL orchids are coming inside on shelves ( south window )with humidity trays. There's no way I'm paying that kind of money again for a hobby! Betty :-)