Most hardiness zone maps are based on a 25 year average. As a result, they can be totally meaningless in any given winter. We are in USDA zone 6a, but we had 3b conditions at our coldest.

Conversely, we've had at least two winters with no worse than 7a conditions. Based on our experience over 50 years we have guesstimated hardiness for each genus we list. Species, variety or cultivar requirements may vary within a genus.

Sun/shade needs may also vary. Plants that need shade in Virginia may do perfectly well in full sun when grown in New England.

We urge you to be skeptical about zone maps and light requirements. Many other factors affect plant performance and durability.