Hi Magga,
I don't really have the answer since I live in such a different climate; I know Beautyberry can tolerate very hot conditions. It is a deciduous shrub that is very slow to come out of dormacy in late spring, so that may be because it waits for temps to warm up. Although, I mostly find it growing under large trees, like oaks where it is shaded from the sun.
Sorry I cannot be more helpful.