Answer: Rocky soil is not necessarily bad, but soild does need to be cared for and "fed" in order to grow healthy plants so you are probably right in thinking that your garden's soil needs some attention. However, adding topsoil over an existing bed is not usually a good idea. Instead, you might consider topdressing with compost and then using several inches of organic mulch around the crowns of the plants. (Shredded leaves are a good source of both.)
As the compost and mulch deteriorate they will naturally feed the soil and help to replenish it on an ongoing basis. You may also need to add additional amendments such as lime or fertilizer but there is no way to make specific recommendations unless you have run some basic soil tests. Your County Extension (727-7850) can help you with the tests and with interpreting the results. They may also have available some basic information on perennial gardening in your local area.
You might also want to read up a bit on basic gardening and on perennials. Two good basic books to start with are "Gardening for Dummies" by Michael MacCaskey ISBN 1-56884-644-4 and "Perennials for Dummies" by Marcia Tatroe ISBN 0-7645-5030-6. Another good book (written by a New England gardener and intended for beginners) which you might find extremely helpful if you are truly interested in working with your perennials a bit is "A Garden of One's Own : Making and Keeping Your Flower Garden" by Elsa Bakalar.
Good luck with your perennials!
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