Hardiness Rating of Russian Sage (Perovskia) Too High

Am paging through your new catalogue and am amazed at how many perennial I have in my garden are actually classified as herbs.
One comment: I have noticed this previously in other catalogues. Pervoskia atriplicilolia is constantly rated as zone 6. It performs wonderfully here in zone 3b with absolutely no additional winter protection. I'm wondering why the zone rating is so high?

It is probably rated that high because someone in zone 6 saw that it was hardy and gave it that rating. And everyone else copied that rating.
Plant hardiness zone rating is an inexact science at best, and at worst not much more than someone's best guess. For years we resisted putting the zones in our catalogue because we felt that they were misleading, as you and many others have found. Unfortunately there is no systematic system in place to rate herbaceous plants in North America, so plants mostly get what I would call charitably a best guesstimate of hardiness. Feeling the pressure of publishing zone ratings for our plants, we too are guilty of dreaming up zone ratings for plants that we first introduced to North America.
We are happy to get feedback from our customers on hardiness zones. We will incorporate your information in our in-house database and it will be reflected in the next catalogue.