I would guess maybe it's that the soil drains too fast, but none of the other vegetables in the raised beds require water in the way these tomatoes do. They have been a serious PITA.

I have a water gauge in one of the pots and they do go from wet to dry by the 2nd day.

media too porous ...

over fertilization ... meaning the pot is over full of roots??

you might not know.. until you dig it out ...

is your pot in full sun and black ... maybe august heat is heating the pot too much ... try shading it ...

ken

Plants in pots require more water (in terms of inches over the surface) because their roots can't go deep or spread out to find the water you applied last week.

Try them in the garden, mulched well, and see what happens.

Peppers do better as "free range" plants, too.

Any ideas on what does well in pots? herbs?

Herbs are good ones for pots. I find pots are my best way to grow cilantro. But that's because I can bring it inside to try and delay bolting. I grow a lot of peppers in pots as well because I want to bring them inside over the winter without trying to dig them out of the ground. I also grow carrots because there are so many rocks around me that my options are either growing them in containers or building more raised beds than I can afford, or putting up with the consequences or rocky soil for carrots.

Angie

Also, if you can put the pots inside other bigger pots, that will help. If not, maybe try to change the color to something lighter so it reflects the sun. Maybe wrap them in white towells??