As we all know hardiness zones are a crapshoot but can be useful as long as the cultivar info is accurate .In the case of JM's hardiness info is questionable since many dealers have differnt zones for many of the same cultivars...maybe to CYA so if the plant gets planted in a colder zone and dies they are not resposible. It is likely in the case of JM's that there just isn't enough studying done to actually know!!!And so many factors in addition to average cold winters effect JM's such as wind exposure humidity etc... anywho the usda zone chart is REALLY bad IMHO I'm sure the original was/is great but it has limited zooming capabilities and is blurry and made for midgets ...at least I cant find my town on it !!! so here's one from Better Homes and Gardens that I think is TOPS check it out!! If this link doesn't work please email me directly and I'll link it to you !!!David

http://www.bhg.com/bhg/category.jhtml?categoryid=/templatedata/bhg/category/data/gardening_zone_hardiness_07032001.xml