My stepdad is building me a greenhouse and I'm so excited. He won't tell me anything about it but all he says it that I am really going to like it!! When I get my greenhouse I wanna divide it into 2 sections. One sorta like a cold house for when plants go dormant or they require temps. around 40 and the other side a warm house for the ones that need 60 0r 70 degrees. How do I do that?