Hoop houses are a nice and simple way to go. A woman here has a sort of nursery in one of them and does okay selling plants she has grown to people in the spring and summer. The hurricane of 2007 knocked it down but it was not that big a deal to set up again. I built a traditional greenhouse and am not completely satisfied with it. I think for the dollar spent these hoop houses work better..
Bottom picture looks kind of like my greenhouse. It is plastic and 6 x 8. It got moved up here this fall. MIL says they are useless here. Hers I guess did not get use and it blew to pieces. I believe it how you use them. No can just grow in bitter winter with no heat. Get creative and will work for some things. Without heat even can extent season fall and spring. you are where warmer. Guy down home was growing corn even. Jim was telling me about him. Gets cold there and he had a bigger hoop house. Here what they report is not really here as is colder. 21 below that one night. Last winter 27.
I had not heard of those plug in thermostacs . The electric oil heater I had on porch for plants seemed to work. I had hundreds of little plants for garden.
"Make it your ambition to lead a quiet life, to mind your own business, and to work with your hands, just as we told you, so that your daily life may win the respect of outsiders and so that you will not be dependent on anybody."