USDA Hardiness Zone Information
Hardiness zones are only one important facet of the garden gem: an indicator or beginning point. Don't be afraid to experiment, for that is how the gardening reference books eventually get changed.
Micro-climates can be created in the garden, gaining a zone or more in hardiness. Mulching during winter is the easiest method. A protected corner that remains a bit warmer can make a difference. If you are a bit too far south of the recommended zone for heat tolerance, try a bit more shade, mulch and consistent moisture.
Often it is not lack of hardiness that kills a plant over winter. If the plant wants to be dry over the winter months, local winter rains can cause rot before it freezes to death. Well-drained soil inside the drip line of a conifer would create a more favorable environment.
Purchase a wildflower guide for your state as a beginning reference. Take hikes and be observant. What are the requirements for the good health of the plant you want to grow in your garden? Does the plant grow in thin soil over a rock, on a hillside, in a seepage area or swamp? Or is it found at woodland edge, or the deep shade beneath an evergreen or in a clearing inside the wood? Get to know the essential requirements of the plant so your relationship will be a happy one.