Answer: You are smart to be planning ahead of time -- this sounds like a big project!
While it is certainly possible to make a list of perennials blooming in the general sequence of early, mid and late season, in my experience trying to devise a planting to bloom according to a strict calendar really isn't possible. The plants perform differently from year to year ann no two years are alike. That is the charm and challenge of gardening with perennials!
Your plant selection will depend to some extent on your soil type and whether the planting is in sun or shade. It will also depend on how much time you want to put into trying to care for it, and to some extent, your personal preference for vaious types of plants, including both their color and overall texture.
I think your best bet right now, since you want the display beginning next spring, is to prepare and amend the planting area based on results of some basic soil tests. (Your County Extension can help you with the tests and interpreting the results; their telephone number is 305-5742.) Perennials give the best results when grown in a properly prepared bed well amended with organic matter, and the only time you can really do that is at the beginning before you plant.
Next, I would do some basic research by looking at a few books on perennials. A good one I like is Perennials for Dummies by Marcia Tatroe ISBN0-7645-5030-6. This book includes sample garden plans and lots of help on selecting perennials that will do well in your garden as well as how to care for them once they are planted.
Good luck with your project!
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