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The New USDA Hardiness Zone Map Is Here

Posted by brandon7 6b/7b TN (My Page) on
Wed, Jan 25, 12 at 22:27

The looooooooooooong awaited new official USDA hardiness zone map is here! Looks like most of Tennessee is now officially rated as 7a and there's a range from 6a (only some really small pockets) to 8a (right around Memphis). I think the way they've used the data may represent a very conservative representation (showing ratings lower than what most of us would consider accurate), but it's still hopefully much more useful than the old map.

Here is a link that might be useful: New USDA Plant Hardiness Zone Map


Follow-Up Postings:

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RE: The New USDA Hardiness Zone Map Is Here

If you download the high-res map, you'll see that there are a few small areas (mountain peaks?) in the Smokies that are zone 5b. I couldn't see those on the regular sized map.


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RE: The New USDA Hardiness Zone Map Is Here

Yes, it's conservative but definitely better. If you use all the Nashville data of 135+ years, it averages out to 7b. I was too lazy to average out the other cities. I speculate that downtown Nashville (between the river and Music Row) could average out to as high as 8a in spots over the same amount of time. Tennessee has so many microclimates because of our topography and location in the Mid-South.


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RE: The New USDA Hardiness Zone Map Is Here

I think you're right, Tommy, about the downtown areas. Knoxville is the same way; in the last couple of decades, downtown Knoxville has averaged to somewhere near 8a. I also had noticed that the map (even when I downloaded the high resolution version) didn't show that fairly large microclimate.


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RE: The New USDA Hardiness Zone Map Is Here

Yes, it definitely does not take into account the heat island micro-climates of any large Tennessee city besides Memphis. The Memphis heat island seems to be larger because of the mighty Mississippi as there is a general surge in warmer temperatures and zones extending all the way up from the Delta.


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RE: The New USDA Hardiness Zone Map Is Here

Finally!!! I am glad that we now have physical proof for what I have been trying to tell you all for multiple years. I agree with Brandon's observation that urban heat islands are still mainly unrepresented for mid-size cities. Apparently, recent updates have started to represent these heat islands for very large urban areas such as San Francisco, Los Angeles, New York, Detroit, etc. Btw, if you look at the past 10-15 years, Knoxville is around 8a!


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