Knowing in which of the USDA Gardening Zones or Sunset Western Growing Zones you live is important to the success of your herb garden.

National Growing Zones Maps of all types are available. Deciphering the growing zones for America, the Canadian growing zones map, and planting zones for Mexico can be confusing. The geographic location of your herb garden, though, is information that you must know before you order your herb seeds or potted herbs and before any herb gardening begins. You should try to thoroughly understand the planting zone or suspected microclimate in which you live and will garden. Know your growing zone by heart.

The 1993 USDA Plant Hardiness Map is the standard on which most maps are based.

Be patent and study Planting Zone Map carefully. As confusing as it might seem at first, familiarity with the gardening zones map will pay big dividends at harvest. It has always been and still remains an invaluable herb gardening tool.

USDA Growing Zones Map

United States Growing Zones by USDA Region

The USDA Plant Maturity Zone Map

In the eastern half of the country, the USDA Planting Zones Map is the standard against which all other planting zones maps are are judged. The area is comparatively flat, so mapping is a matter of mapping lines moving north approximately parallel to the Gulf Coast in 5 degree increments. The lines tilt northeast approaching the east coast until they cross the Eastern mountain ranges where the varying altitudes cause greater variations in planting zones.

Sunset Western Garden Book is the standard among gardeners who live in the 13 western states.

The Sunset Western Growing Zone Map is the more accurate reference in the Western US. The criteria that define the western climate zones are more complicated than in the Eastern US. Many factors other than the winter low temperatures on which the USDA map is based determine western growing climates. As weather moves east from the Pacific Ocean the air becomes more continental as it migrates over and around the Western mountain ranges.

The Sunset Western Growing Zone Map recognizes the difference between garden climates in the east and west by dividing the US into 45 growing zones. The 100th meridian, a north/south line which runs roughly through the middle of North and South Dakota and on south through Texas west of Laredo. Sunset Growing Zones 1 through 24 are west of the 100th meridian and Sunset Planting Zones 25 through 45 are east of the meridian.

This system acknowledges the complex gardening regions of the west and recognizes that in many cases neither minimum nor maximum temperatures determine the survival of a herb plant.

Sunset Gardening Zones are based on regions where particular plants flourish, not on regions that share a feature such as temperature or heat. Instead of matching a plant to an established zone, the zone is created to match the plants.

Arbor day Foundation growing Zones Map:

The Gardening Zones Map of the Arbor Day Foundation shown below illustrates an interesting trend. Compare it to the older USDA Growing Zones Map. You will notice a steady warming trend between the two maps.

National Arborday Foundation Heat Zones Map

Herb seed catalogs and garden nurseries occasionally use a form of their own gardening zones map which is based on the USDA Growing zones.

Most are based on the standard 1993 USDA Plant Maturity Zone map. In an effort by the suppliers to simplify the process for you, each may vary slightly due to the interpretations shown in their seed catalog. Just be aware on which information the growing zone map you are viewing is based. Make your buying decision based on each individual supplier's recommendation indicated on their own growing zone map.

The USDA Planting Zone Map is the most widely used by industry.

The USDA Planting Zone Map, whether you live in the Eastern or Western United States, is still the guideline used by most garden catalogs, Internet garden suppliers and direct mail herb suppliers. A herb gardener must be aware that growing zones indicated by one garden supplier may differ slightly from the gardening zones presented by another. Both, though, are doing their best with the information they have. In general, asking questions and paying attention is the best rule when deciding which Gardening Zone Map you will use.