Maintaining a Greenhouse in the middle of winter
This may not be the best forum to ask about greenhouses. Yet, I still feel this crowd would have more experience in winterizing their greenhouses.
I saw a pic that orangelime1 posted in "2013 taste test winners"
It was a pic of his(?, sorry it's an ambiguous name) greenhouse covered in snow and inside he had a bunch of happy citrus trees.
I guess my question is, how does one manage the temperature to provide a living environment for citrus trees.
I saw the bubble wrap, and I know about using black milk jugs with water. But there has to be some sort of main heat source that's safe and reliable.
Keep in mind that where I live, temperatures and fall to -5 F (-20 C) but is often around 15-20's F