Answer: There are any number of plants native to the Philadelphia area, however, your most reliable garden performers may also include some non-natives which are well-suited to your actual garden conditions.
To improve your chances of success with your plants, you may wish to perform some basic soil tests. The results will tell you how to improve your soil so that the plants will grow better. Your County Extension (560-4150) can help you with the tests and interpreting the results.
Even with native plants, you will still need to select plants suited to your light and soil conditions -- some prefer shade and some prefer sun, some prefer moist soil some prefer dry. Finally, no matter which plants you select, you will still need to care for them regularly until they become established -- this often takes a year and sometimes longer.
For some good basic gardening information to help you make the most of your garden with the least amount of work, and to figure out which types of plants would probably do best for you, you might want to take a look at a book I particularly like "Gardening for Dummies" by Michael MacCaskey (ISBN 1-56884-644-4).
For more detailed information about local native plants and how to select and care for them, these may be helpful:
Morris Arboretum http://www.upenn.edu/morris/
Pennsylvania Horticultural Society http://www.libertynet.org/phs/
Longwood Gardens http://www.longwoodgardens.org/
Good luck with your new garden plan!
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