The first thing you need to do is check with the local county ordinances on using nitrogen and phosphates at certain times of the year. If there are stringent guidelines you will have to use slow-release in the active growing season unless you want to risk getting fined. I use slow-release for foliage plants but for flowering and fruiting plants I use Miracle-grow at half strength every 2 weeks during the blooming season. If a plant is small you will need more nitrogen to get it going, but the middle number is the one that promotes flowering and fruiting. If you go overboard with the nitrogen it will grow and grow and produce lots of leaves but you will have less blooms. In some communities you can't even buy certain fertilizers with high numbers, especially high-nitrogen for lawns. I don't fertilize in the winter except for winter vegetable crops such as greens.

Flowers blooming is usually more about seasons, conditions and/or age than fertilizer. Yeah, if the soil is lacking in certain nutrients, then it can affect blooming, but that's where 'Right Plant, Right Place' comes in. Planting azaleas right next to a concrete driveway and expecting them to bloom is an exercise in frustration and hair pulling. They might bloom, but not nearly as well as they would in a mulched bed around the base of a oak or pine tree. Some people use fertilizers to extend their blooming period or perhaps make bigger, more plentiful blooms, but relying purely on fertilizer to get blooms is going to get expensive and probably end up in disappointment.

Personally, I only fertilize in March with a slow-release general fertilizer to give all my plants a wake-up meal to get them going as temps rise. After that I leave it up nature for the most part. There are some plants like my blueberries that need special attention, but the vast majority of my plants are planted in areas/conditions that suits them. There's only about two-three months a year where I do not have something blooming in my yard and that is certain to change as some of my winter-blooming perennials get more established.

Along with Rita's advice I would suggest contacting your Ext Office to have your yard inspected. I believe they offer this service where the Horticultural Agent will visit and let you know which areas would be best for what kind of plants. One of the big things about having a garden in Florida is the idea that sometimes it is just better to give up on certain plants that just don't do well. A lot of people don't like thinking about this and they repeatedly buy and plant the same things, refusing to accept the fact those plants just won't thrive here. And Big Box stores make LOADS of cash off these people.

Two of my favorite books for gardening/landscaping in Florida are "Gardening and Landscaping in Central Florida" by Marlys Bell and "Tough Plants for Florida Gardens" by Felder Rushing. The first really just spells out the pure and simple facts of what we can and can not grow due to climate conditions and basic landscaping practices. The second has several plant suggestions along with pictures to help you plan your beds. I think between those two books any one could design a good looking yard that will thrive in Florida with little hair-pulling and maintenance.