I just got a small one last year and i suspect that while it may get warm during the day it will dip too cold in the dead of winter without some sort of heat source. overall I do like it a lot, my wife does too. I don't have a good sunny place in the house to start plants and was able to start plants that i normally take from seed in the ground in april and transplant them in the garden in may and had produce much earlier than i normally do. It has also extended thew wifes fresh herbs that she grows in pots which are normally all done by now. They are still doing great despite the cold nights we have had. Next year i'm going to keep an eye on the overnight temps in the greenhouse and see if i can do my own tomatoes and peppers from seed. I have always bought them in the past. Here are some pics of it. I built the wife a cedar potting bench with built in dirt storage which she has found immensely useful for all her flower garden stuff. I had to build a wood frame for the bottom because there was a uneven concrete slab where we wanted it to go and i didn't want to hammer it up or replace it. Frame is all cedar, I filled the frame with pea stone and built a walkway as well so we don't kick the stones all over.