posted 14 years ago
First of all, the "National" USDA Zone maps are rather generic. If you can find a state map (check with your County Extension Agent), it is much more detailed. There are many microclimates which do not show up on the small scale (national) maps which will show up on a local area map. You could actually be in zone 4 (or 2!).
Just as there are mild winters, there are also the opposite, which may push you into a colder zone once in a lifetime. With a little effort, you can often "fool Mother Nature" by 1 or 2 zones, but 3 zones (30° F) is pushing your luck. The more artificial measures you take to cheat the system, the further you wander from "sustainability" and "permanent".