River - I live in Lafayette, La. similar climate. Harvest as soon as you have enough leaves for a serving. Just pinch the leaves off rather than harvest the entire plant. DITTO Applestar - larger containers will prolong your harvest. Move them to a shady spot to delay bolting.
Do not expect a long season. Temperatures are getting up there and your lettuce will bolt.
DITTO Catgrass on fall planting.
I will be back shortly with information on fall planting.
http://www.lsuagcenter.com/NR/rdonlyres ... de2014.pdf
Because of the similarity of our regional growing conditions this information will apply to you. It is a large publication. There is a growing chart at the beginning. Scroll through to find specific information on growing greens.
I treat all greens (lettuce, spinach, collards, kale, mustard greens, cabbage), many root crops (turnips, carrots, beets), cauliflower and broccoli as fall crops.
Enjoy this years harvest and try fall planting next year.