You may be in a spot where the soil has been contaminated by root nematodes. Be sure that you plant the kind that is resistant.That's a common problem here. I don't know what the solution may be other than planting them in containers. Most of the soil is sandy and needs more watering than you may be used to. Which means it's easy to overwater. With tomatoes, sometimes it seems you just can't win.

Have you checked over on the Tomato Forum?
Good Luck
PB

You probably have a three-fold problem.
1. Root knot nematodes. In this area tomatoes are best grown in large pots elevated on bricks.
2. Select tomato seed specifically hybridized for southern humid heat, such as Homestead, which is a determinate type. Also, try Matt's wild cherry, and Black cherry, Abraham Lincoln, Hotset, Cherokee Purple. Hopefully others may be able to suggest good varieties.
3. Growing location may also be your problem. Try setting your potted tomatoes either under high dappled shade or morning sun with afternoon shade.

A quick tip. In my experimenting to control various tomatoes problems I have found that planting three young Sage plants in the same pot with my tomato seedling in the spring has greatly improved the plant growth, induced better fruiting and the tomatoes I treated in this manner during 2004 are still growing and setting fruit well today. Although the various blights did affect them, I cut off the browning foliage and the tomatoes sent out vigorous new growth and blooms. I plan to grow each tomato plant next year with three Sage plants in the same planting hole, keeping them trimmed back if necessary.

You are right, compared to up north, tomatos and nearly everything else is difficult here. I have found that the soils is so sandy it is worth the effort of make raised beds so that you can more easily get the organic matter content up. Also makes it easier to mulch and control weeds.

As for tomatos, I have tried many types over the past few years. Most, even those supposedly bred for the south with multiple disease resistance, barely live long enough to produce one fruit. The only cultivars I have had success with is 'Early Girl'. Seems strange since it is bred to be early for northern areas. I suspect that it may have some tolerance to tomato spotted wilt virus. The other factor I have found helpful is to start them indoors and keep them indoors as long as possible. If you can delay the time of infection with TSWV, which is carried by insects, the effects on the plant will be less.

As a final note, almost inevitably your garden will fall apart sometime in July. The heat and humidity will kill a lot of things. Other crops will just be past their normal life span. This is hard for a northerner to take, but it is the way it is.

Pc.

I have had success with roma and cherry tomatoes with very little effort. I like sweet 100s and sun gold and aside from hornworms, they do great. I have had very little success with slicers, but I am trying Cherokee Purple and Arkansas Traveler this year for the first time.

Good luck.

Grow them in containers with store bought soil!