@chris1948 I put up a plastic popup GH on my patio last winter for plants that wouldn't fit in my 6 x8. Popup was about 5 x 6 and 6 ft tall. I heated it with two or three light bulbs. Those outdoor types that put out some heat, although I find the CFL also work. I also bought those space blankets, that look like foil coated Mylar from Amazon for about a buck each. I draped those around the plants or inside walls when it was going to be extra cold at night and they worked remarkably well at containing the heat. I even used some of those red rope lights. I never needed a heater in there. I used clothespins to tent them together over the plants and made sure the lightbulbs were far enough away to be safe. I use those blankets along the walls of my Harbor Freight GH too, when really cold, securing with clothes pins or clips. They make a world of difference.
