What hardiness zone is Philadelphia?
Philadelphia is in hardiness zones 7A and 7B. The best way to find your hardiness zone is to go to the USDA Plant Hardiness Zone Map page and enter your zip code in the "Find your hardiness zone" lookup.
If you are just getting starting with city gardening, take a look at our subject guide Urban Gardener: Gardening in Small Spaces. This subject guide will be useful in finding information about gardening in a small space, both indoors and outdoors.