Answer: The best perennials to use will depend to some extent on the soil and growing conditions you have to offer. You should run some basic soil tests and amend your soil as indicated by the results. Your local County Extension in New Jersey should be able to help you with the tests and interpreting the results and may have suggestions about plants that perform particularly well in conditions similar to yours.
In any case, perennial beds are almost always greatly improved by the addition of copious amounts of organic matter such as compost, well-aged manure and stable bedding, or rotted leaves. After that, your choice will be influenced by whether the spot is sunny or shady, well drained or moist, how much time you plan to spend caring for them and so on.
You might find some more specific ideas in a basic book or two about perennials. Here are some you may 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.
Enjoy your perennial garden!
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