So I was sold when I found TexasPrepper2's video on YouTube. He uses cattle panels as the main structure and it is pretty robust (this cattle panel design is the main structure we also use for our pasture raised chickens). He also sounds like he could be Matthew McConaughey's uncle, which makes his videos pretty entertaining. It must be a specific Texas accent.
At any rate. I was curious to see how the structure would do with snow on it, but I already had plants started and the heater going before we got our first snow this year. It was so warm inside that the snow melted as fast as it feel. I heated the greenhouse with an old Kerosene Heater my dad had in his shop. I would leave it as low as it would go which would keep the greenhouse's temperature around 45 degrees. Even on the day the high didn't get out of the single digits, which is exceptionally cold for us here in the center of NC, the greenhouse stayed above freezing and didn't break the bank.
We got several trays of plants going now, broccoli, kohlrabi, cabbage, collards, chard, and have just started to plant them out in the field. It is always exciting to start something from seed and there is a part of me that is always amazed to come back by and see the first seedling starting to sprout. It boggles the mind. Definitely would recommend the project.