What is the coldest it has been at your place ? look At the usda chart and compare .These are not written in stone and fluctuate/The usda hardiness map says I'm in 8b but the thermometer says I'm 8a .hoped I helped .P.S. always go with the lower reading.........Rand

The best, and most time-consuming, way is to find climate data from the nearest weather station to you (similar altitude, etc.) and take an average of the lowest winter temperatures (lowest for every year) over the last 30 or more years and then plug that into the USDA formula. That would be the real-deal zone information for you.