Stitch,
Do soil tests and add the recommended nutrients to your plots prior to planting anything!!!! Otherwise, you're just pi$$ing away $$$$ and will be very disappointed. Best way to get soil tests done is through your local ag extension service-
Call Them!!!. Cost is around $7 per sample for analyzing and will tell you everything you need to know (and add to your plots). Some might tell you that there are "do-it-yourself kits" that will work fine-don't believe it. Go with the extension service and ask them all your questions on how to prep your soil, what grows best where, etc. Use them, that's what they're there for.
Proper soil ph levels are as important as water to your food plots. If the soil is acidic (<5.5), it doesn't matter how much fertilizer you throw out, your plants will not grow very well, if at all.
N. Fla/So. Ga probably has the same type of poor, acidic soil that we have to deal with where I hunt in Ga. You will need lime and a bunch of it, maybe as much as 3-4 tons/acre to raise the ph to 6.5 (the soil test will tell you). Ground aglime (agriculture lime) is the best way to raise your ph. Aglime has calcium and magnesium in it as well-good for deer bones and antlers. Get it spread now, incorporate (till) and you should be ready to plant this spring. (It takes a few months for the lime to neutralize the soil.) We buy ground aglime by the ton from a local ag service. It's tough to spread, so we have them do it for us with their spreader trucks. Price is really dependent on location and distance from the supplier to your food plots. We payed around $40 ton delivered/spread last spring which is way cheaper than the bagged/pellet stuff. Find a local supplier and ask questions. They can also deliver/spread fertilizer in bulk.
As far as what to grow and when, your local extension service can make good recommendations based upon your soil type(s). The below websites offer good info as well.
http://hubcap.clemson.edu/~blpprt/acid2.html
http://www.cooperseeds.com/pages/wildlife/
My advice would be to establish/prep the food plots, do soil tests, add lime and recommended fertilizer/micronutrients at the recommended time and then plant buckwheat this coming spring. Seed is inexpensive at around $30 for a 50lb bag (will do an acre). It grows very well and will tolerate poor soil. The great thing is that it will mature in about two months. Bushhog it, till, and plant again. This provides "green manure" to build up the nutrients in your soil. As you're in N Fla./S. Ga, you should easily get two plantings/maybe three in from spring to early fall.
Do another soil test mid-late summer. After your second/third planting of buckwheat, add more lime/fertilizer as recommended by the soil test. Then, plant your fall/winter plots (clover, oats, etc.)
One other thing-don't bite off more than you can chew. It's far easier, cheaper and satisfying to have one awesome food plot than several medicore ones.
The above is
experience-I consider the time it took to write well spent if it saves a fellow hunter some $$$ and headaches.
Sako