Here in Texas, I have recently learned that you must plant out tomatoes by March because the heat in June just stops production. This perforated plastic is a popular product because it protects the young plants from wind, but lets them get the light without overheating http://www.territorialseed.com...
Baltimore County, MD (Zone 7a) A bit of this and a bit of that
Thanks guys!
I'm not sure how much cold protection you need in Texas, but I was in a similar zone to you two (right on the 7b/8a line), so you can probably grow greens and herbs all winter with something like my little tunnels.