I live in the Central Valley of California. It is very hot in the summer and are winters are brief and fairly mild. The Leucantha should do really well by you.
Some things:
* they do need regular water to look nice and do well... at least weekly;
* they need a good pruning after blooming, also pulling out the really old stems;
* they also appreciate some all-purpose fertilizer once or twice a year.

Thanks for the tips :)