Growing a Zone 9 Herb in Zone 5

Can a zone 9 perennial be treated as a zone 5 annual? Found a plant in your catalogue that was interesting but is hardy to zone 9.

Absolutely. This is one of the main reasons why Richters resisted listing hardiness zone ratings for herbs in the catalogue for many years. We were and still are worried that people might think that plants hardy to warmer zones cannot be grown in their colder zone.
In fact, most of us garden with plants that are hardy warmer zones. Common flowers and vegetables such as geraniums, petunias, and peppers are perennials, but not hardy in temperate zone, so they are treated as annuals in colder zones. Of course, we know that they can be grown very successfully as summer annuals.
Similarly, many herbs that are hardy in warm zones will do very well in cold zones. We routinely grow sweet marjoram and rosemary in our zone 5 as summer annuals, but in zone 9 these are both perennials.