I have been living in Florida zone 9a for about 2 1/2 years now, but I have been into gardening for only about 6 months. According to locals, we're not supposed to see much of freezing at all around here. But my first two winters here haven't given their claims a lot to stand on. Temps have, briefly, dropped below freezing a few times each winter and last year one freeze managed to kill my Key Lime down to ground as well as some pentas. I do not have a lot of yard to work with and while I wouldn't mind putting a small greenhouse in one corner for winter protection of some plants, my wife would rather have a pergola. So I'm left with wondering if it would be possible to have a structure that would perform double duty: Pergola in the spring, summer and fall, Greenhouse in winter. In theory it would be doable, simply enclose the pergola during the cold months. In practical application... well... that's the part I'm not so sure on.