The perennial herbs in our data base have a zone hardiness rating. Since the United States has vast differences in climates, this zoning system was set up to help gardeners know which plants are best suited to grow in their area.
If a range of zones, for example, zones 4-9, is indicated for the herb, that herb is known to be hardy in zones 4, 5, 6, 7, 8, and 9. Suitable hardiness means a plant can be expected to grow in the zone’s temperature extremes, as determined by the lowest average annual temperature. Annual herbs last only one season, therefore they do not have a zone rating.
Keep in mind that local variations such as moisture, soil, winds, and other conditions might affect the viability of individual plants.
Click here to see a Zone Map.