When you're buying plants at your gardening center, you'll see a tab that might say, "Plant Hardiness Zones 4-8." Hardiness Zones puzzle a lot of people. Once you understand how they work, you'll see how useful they are.
Years ago, the US Department of Agriculture devised a method to help people judge what plants could survive the average low temperatures in different parts of the country. The Department created a map of North America broken into 11 zones ranging from cold to warm. Zone 1 includes Fairbanks, Alaska and the northern islands of Canada. Zone 11 includes most of Hawaii. The bulk of the US mainland ranges between zones 4 and 8.
Most plants and seeds are sold with the optimal Plant Hardiness Zones indicated. You might have a microclimate that could handle a wider range of plants, but you'll have better luck if you work with plants rated for your area. To see the complete Plant Hardiness Zone map, go to www.usna.usda.gov/Hardzone/ushzmap.html