I don't have an answer to your "disappearing" "Blackberry Lily", Lin. Not only have mine been in the ground and in pots for five years, if you allow them, they will propagate by self-seedling. Though the literature says they do well/best in full sun, I find that mine do best with some afternoon shading. These plants are actually evergreen in zones 9-10 but mine die back each fall and re-appear each spring. I am no longer on the coast, but these plants grew well for me and were pretty much evergreen when I lived on the Mississippi Gulf Coast. They are salt-tolerant and poor-soil tolerant, and thus I would expect them to grow in Florida-conditions as well as they do here. I fertilize my plants with Osmacote, applied in late winter before the plants emerge from dormancy.