They should do fine where you are. Free drained spot in full sun. Great in containers as root restriction makes them flower well. Still good in the ground and happy in stony soil too. I have this species in the ground in Northumberland (NE England) and it has come through a very bad January which was one of the coldest in the last fifteen years. Southern Texas though continental is relatively mild (been there :-) ) so as I say, you should be fine with it.