Morgan, are those Strelitzia reginae or Strelitzia nicolai? They look like S. nicolai to me. The reginae are the smaller ones, and the nicolai the ones that get to thirty feet tall. They look planted too close, whichever they are. Reginae should be planted 24 - 36 inches apart (me, I'd do them at least 36), and apart from the pavement (me, I'd do them at least 36), and the nicolai, according to the website Dave's Garden (very useful site), 4 to 6 feet apart.
You'll save yourself a lot of grief in the long run if you a) buy your plants from a nursery with very knowledgeable staff, and b), no matter what they say, also research the plant online.
One of the good go-to sites:
http://davesgarden.com/guides/pf/go/2466/
My own reference bible is Sunset Western Garden, but they direct their publishing energy and deliniation of climate zones (both re heat tolerance and cold hardiness) to the western u.s.. Many plants grow in both Florida and CA, though.