I’ve owned commercial-built greenhouses, and I have built and owned some from scratch. I believe the one I have now is about the best you can get for the money – for several reasons. It is the Mittleider Greenhouse, and it’s in appendix D of the Mittleider Gardening Course, available at www.growfood.com.
Several other of Mittleider’s books have the plans. Consider the Mittleider Library CD, which has all of them.
1) It is very strong, and will withstant virtually any amount of snow or wind.
2) It is less costly than the commercial models.
3) While not “portable” it can be disassembled and moved.
4) The Layout was planned by a man who is really expert in time management and volume production.
5) Built-in continuous ventilators running the length of the roof and along the walls make electric fans unnecessary.
6) If 8 or 10 mil dual or triple-wall polycarbonate is used, it is very efficient to heat.
I highly recommend these plans for anyone serous about growing your own seedlings. They can be had free by contacting us and in the subject line write “Please send Greenhouse Plans”.
The Mittleider Gardening books and Manuals teach all you need to know about this subject, and can be purchased in the Store section, or as digital downloads.
A digital copy costs 30-40% less, and is available instantly! I HIGHLY recommend you look here https://www.howtoorganicgarden.com/Products_pdfs.htm for the best gardening books available anywhere! Get one NOW and be gardening TODAY!