Thanks to all of the info I've found on this forum, I was able to build a small greenhouse for overwintering my temperate bonsai here in zone 7A. I am hoping to also house tropical trees in spring to create enough humidity for aerial root growth as well. Since it is so small—barely a greenhouse by some standards, but better than a plastic covering over pvc—any suggestions or recommendations for heater and thermostat? I used Tuftex corrugated polycarbonate, but I'm not sure about its insulating properties. I have a vent at the bottom and another on top at the opposite side, as well as 2 muffin fans (110 com) for circulation. Any comments or suggestions are welcome and appreciated.

It looks like you have the perfect little greenhouse for your needs. I hope you enjoy using it for your Bonsai plants.

That is so neat , makes me want one
Did you find plans somewhere? or just a clever carpenter?

Wish I could help on heating , I just use a small lantern to keep my greenhouse above freezing
the lantern works down to about 26 degrees
I only just extend my season by a few weeks not all winter.

Thanks, Cinda! I've been wanting one for so long, but have limited space, so even the smallest kits were just a little too big for my space. After watching lots of You Tube videos and gathering info on this site, I decided to build it myself. This is my first attempt at building anything, but I learned a lot and made mistakes. Overall, I am happy with it, but not sure about the heating in the winter. We can go to 0 here in NY, and I wanted to keep it at around 35-40 in order to overwinter my temperate bonsai. The typical greenhouse heaters are overkill for the size (6 X 3), and the personal space heaters seem too small. I will keep looking and maybe someone on this forum can make a suggestion. Good luck with your plants!