The white-flowered oak leaf hydrangeas are supposed to be easier. The big mopheads really like rich, acid soil cooler temperatures and a nice long dormant period in winter, none of which Florida supplies most years.
I kept a couple of white lace-caps (grocery store rescues, from the holidays) alive for 3 or 4 years in large pots, under my big oak trees but they were terrible divas. I finally had enough of coddling them, planted them in the ground with lots of nice compost, and left them to their devices. They were gone the next summer. This pic taken 5 years ago.
A nice alternative plant is Dombeya, with beautiful clusters of pink flowers.
Tropical Hydrangea (Dombeya wallichii)
