Answer: It sounds like you have a lovely garden. It is true that each type of perennial has its own requirements, not just for division or splitting but also for planting preferences. Since you have so many different types, you might want to look at a book or two for basic information and also for variety by variety care recommendations. Once you have identified each plant you will be able to determine the best time of year and method for division -- if indeed that is even recommended for the plant in question -- some plants, such as peonies and baptisia, are actually best left in place indefinitely. Here are some books you might find helpful:
"Perennials for Dummies" by Marcia Tatroe ISBN 0764550306; "Rodale's Illustrated Encyclopedia of Perennials" by Ellen Phillips and C. Colston Burrell ISBN: 0875965709; and "The Well-Tended Perennial Garden : Planting & Pruning Techniques" by Tracy Disabato-Aust, Steven M. Still ISBN: 0881924148.
Also, although many plants can be divided or transplanted in the fall, the vast majority can be moved in the spring with equally good results and in some cases is preferred. This allow you plenty of time to do your research, prepare your soil in new planting areas, and learn about the plants before you start moving them.
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