Lets see pictures please.
And tell us what you filled the pots with.

You said on lanai so in containers? And "garden mix soil"? In containers any sort of "soil" compacts and causes drainage problems. If you used Miracle Grow Garden Soil is says on the bag "Not for Use in Containers".

Otherwise need more info please. Size of container? Potting mix used? Fertilizers used? Watering regimen? etc.

Dave

1) Miracle Grow Garden Soil (the yellow bag) says not for use in containers on the bags. It need to be replaced with a proper soil-less potting mix.

2) if you mean 6 they inch x6 inch containers are far too small for tomato plants to grow in. So the plants are probably rootbound and need to be transplanted into much larger containers anyway.

3) If you mean 6 feet x 6 feet for this "portable garden container" is that what the tomatoes are in or "other" plants.

4) what have you fed them? What fertilizers? This is the primary problem shown in the photo.

5) 3 hours of sun is only 1/2 of what they need to survive much less thrive. 6-8 hours minimum is needed. That is the next most important issue.

6) I water by container when soils dry Soil should be allowed to dry. Tomatoes require low levels of consistent moisture in the soil. If you mean the surface is dry then you need to stick your fingers down in it and keep it very lightly moist at the root level.

Dave

Where in Florida are you? Depending on how far south you are, it might be too hot/humid soon for tomatoes. (If it isn't already.) My mom is in South FL Z10, and down there they grow tomatoes over the winter.

I'll need to figure this out because we'll most likely be moving down there in a couple of years.