Answer: It sounds like your needs could be adequately met with a small covered structure like a cold frame. You can put hundreds of plants in a very small area! Take a look at a 72 cell tray at a local nursery and imagine how much room you might need. Just build it larger that you think...you know you'll find plenty to fill it up!
Building a quality, "permanent" cold frame can cost quite a bit, depending on the size and choice of materials. Many southern gardeners improvise their own. Our warm winters and lack of snow loads make it easy to get by with a lightweight temporary structure.
One example is to build a frame out of 1" PVC plumbing pipe (it is very simple and inexpensive, and goes together like "tinker toys"!) and cover the frame with a 6 to 10 mil clear plastic. Both materials are available at your local hardware store.
A cold frame can be heated on a cold nite with a heater coil or even a light bulb or two. Make sure extension cords and connections are not damaged and all connections are weatherproof to avoid problems. Expecially cold nites may require a cover (like a blanket) to hold heat. Design it to allow a hinged or removeable top. Warm sunny days will cook your plants, even in February.
Have fun and good luck with your gardens!
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