When I lived in OH I killed a few of these from too little sun, soggy peat. A couple hours of early morning sun should be great. The ones I have here in AL now like that a lot, definitely humid here.

I've generally had good luck growing rex hybrids both in containers and in the ground in Washington, DC but some rex hybrids are more heat-tolerant than others, so in part it depends on which one you have (unfortunately, most are sold without any names). In general they want bright light but not direct sun, and a moist, well-drained soil or potting mix that doesn't stay too wet, but also never dries out completely. As suggested above, keeping them too wet is probably the surest way to kill them.