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                  Idyllwild Garden Club
Discovering the Joy of Mountain Gardening

                    Partially Supported Through the Generosity of the              
            Idyllwild Community Fund and the Pine Cove Water District

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Current Plant Hardiness Zone Map-Click here



 Feb. 2012
by Harold Voorheis, Horticulturalist
Idyllwild Garden Club
 For all those frustrated gardeners, good news is ahead. It looks like plants/shrubs/trees will soon start appearing with far more accurate "hardiness planting zone" labels at nurseries, garden centers and reference materials like books, articles and websites where we go to get specific information about a particular plant.

The 2012 USDA Plant Hardiness Zone Map is the standard by which gardeners and growers can determine which plants are most likely to thrive at a location. The map is based on the average annual minimum winter temperature, divided into 10-degree F zones.

For the first time, the map is available as an interactive GIS-based map, for which a broadband Internet connection is recommended, and as static images for those with slower Internet access. Users may also simply type in a ZIP Code and find the hardiness zone for that area. All that is necessary is to go to the website, and enter your zip code. For example, new USDA average annual minimums for Idyllwild (92549) is now Zone 8a, 10-15 F, Mountain Center (92561) is Zone 8b, 15-20 F, Banning (92220) is Zone 9b, 25-30 F, and Hemet (92543-5) is Zone 9a, 20-25 F (instead of all four listed together as the same zone in many earlier publications).

Let me mention a word about the Sunset Zones from the Western Garden Book that have been the mainstay for so long now as superior to the old USDA zones. Idyllwild is Sunset Zone 7, which is collectively the "southern California mountains" along with "California's Gray Pine Belt" and "Oregon's Rogue River Valley" that are given as location examples. The listing for Sunset Zone 7 is, and I quote, "typical winter lows range from 35-26 F, with record lows averaging 18-0 F." Now you do not have to go far to conclude that the new USDA zones are far more specific--just one look at the difference between Idyllwild and Mountain Center in the new USDA revisions demonstrates a superiority even over the Sunset Zones! It is more than likely going to be awhile before adjustments get printed for all the plant world out there. So meanwhile, for Idyllwild at least, if the plant cannot withstand or survive a winter temperature of 10 - 15 F, you may be wasting your money to purchase it. That said, there are those of us who have successfully "pushed" the margins a bit with some plants, giving them more "protection" or a more "protected site in our garden" from winter lows here, and have succeeded. But many neglect to report the "failures" so beware!

I have copied the detailed release about the new zone map below. We thank our member Pat Hughes for alerting us to this information!