In South Florida, you have an abundance of sunlight and moisture that most American gardeners would kill for. The problem is that most plants distributed by the big horticultural industry aren't adapted to your area and can't handle the heat or humidity or soil composition. You may be planting at the wrong time of year (this time of year is terrible for planting in Florida but great for planting up North). I would plant shrubs native to Florida in your yard. Make sure they've been bred in a Florida nursery. Plant them in November or December. Watch a YouTube video on how to plant if you haven't done it often before. Water them heavily whenever they don't get any rain for a week for the first several months after planting. You should be fine.