Have you seen the new zone map? We all know about global warming. The USDA hasn't come up w/ a new zone map to reflect it, so the Arbor Day Foundation did it & gave it to the USDA. The USDA rejected it! I guess the gov't can't admit that Global Warming is real yet!
Here's the new Zone map
You can find your zone on the map, or by putting in your zip code. You can see the changes from 1990 to 2006. You can download a High Res map.

I remember this being discussed in a thread earlier last year HERE. Thanks for bringing this up again. It seems it's still being as disputed now as it was back then. Yet, the USDA still hasn't seen fit to put their maps where their mouths are, so to speak, by updating their highly-outdated zone map.

I did a search by ZIP code and the zone that came up is wrong for my place. We were way colder this last winter in our ZIP code than for the zone they list.

While it is a bit warmer in the summers here now the winter temperatures are not any warmer and that is what is used for setting the gardening zones. But that is just my area. I have no idea how this new map works out for the rest of the country. You all will have to make up your own minds on that.

When I first moved here, my "zone" was classified as Zone 6. It then morphed into 6A, then 6B. Now, even the local extension agencies and just about every nursery-person I've spoken w/all agree we're a bone fide Zone 7.

Don't forget, just as important as Zone Hardiness is Heat Zones. More and more plant descriptions are including Heat Zone indicators. Considering how much warmer my summers (make that excrutiatingly hot and dry), knowing my heat zone helps too. It's an indicator of how many days during a given season temps are above, I believe, 85 or such; letting you know whether a plant can take that much prolonged heat or that many heat days w/o being too stressed to thrive.

I know I made a post about it here a couple years ago. If I search, I could find it. But I think I'm in Heat Zone 7, too. I used to have it listed in my sig line, but opted for "Twilight" since that seemed more appropriate for my state of mind most of the time.

I will have to see if I can find a heat zone listing.

All I know for sure is we get well over 100º for about a month every year. The area has always got that hot here but the locals tell me that it seems to last a bit longer now than it used to.

At least it is a dry heat so it is easy to live with. I guess that is why it is called a desert.

Whoops! Found the thread. Boy! Older than I thought! And I was mistaken about my Heat Zone. It's Zone 6.

Here's the thread with a link to American Horticultural Society's map. (They're the ones who came up with it.)

Also, don't forget the Sunset Zone maps which are different than the others.

Thanks

no change for me still Z6

I ran across something interesting several months back when I was researching some gardening question I had. There was an article online from, I believe, 1976 that had my area listed as Zone 7! (and while I'm technically in 8b, it's a 9 now for all practical purposes)

When I tried to search further about the Hardiness map from the midseventies, I never really found anything to verify that. Ditto any changes the USDA had made in the zones since that time.

So maybe it wasn't youth that made me more tolerant of the summer heat? What, hot flashes aren't to blame?!?

I'm not sure relying on "maps" is the way to garden. Just like road maps--even MapQuest--they're flawed for various reasons (including politics). We'd all probably be better off paying attention to our own local weather and land, and then experiment. I moved less than 30 miles north in 2006, still in zone 6(a), yet conditions are different.

Jems is right. Zone maps (heat or hardiness) are merely guidelines, benchmarks or 'jumping off points' for both growers, retailers and consumers/gardeners. One shouldn't rely upon them, but merely utilize them as another reference tool.

If I fell in love w/a perennial and there was no criteria, no data, no indication whatsoever as to whether it'd winter over here in Central Jersey or whether it was indigenous to Southern Florida...I'd waste a heckuva lot of money. At least, if I had some better idea that it was hardy only in areas like S. Florida, if I loved it that much, then I might still buy it. But I'd treat it as a rather-expensive annual.

"Zones" are relative not just to the area of the country, but to areas as concentrated as the 'zone' around your garden. All sorts of factors such as trees, sun/shade exposure, soil conditions, drainage, wind exposure, proximity to a structure, etc. can create microclimates or "microzones" that are specific only to you, and could even differ from your next door neighbor's.

The Plant Hardiness Zone Maps are one guide to aid us in plant selection, but I would not be too quick to utilize the new one which is based on too little information.
In this are of the world, based on 3 years of information, the latest date of frost was moved from May 25 to May 5 and anyone that planted frost tender stuff at that time had the plant frosted on May 29. I have used May 30 as my Latest Date Of Frost since the 1950's and have not had more than twice any frost related problems.

No change for me in the new map either. Still zone 4.

If we assume they used the same methodology for the mid-70s and early 90s maps as some are asking for them to do now, then the mid-70s maps would reflect a historically colder period.

quote:

A survey completed last year [1973] by Dr. Murray Mitchell of the National Oceanic and Atmospheric Administration reveals a drop of half a degree in average ground temperatures in the Northern Hemisphere between 1945 and 1968

http://sweetness-light.com/archive/newsweeks-1975-artic...t-the-coming-ice-age

I'd be leery of trusting 20 year trends, instead of century or more experiences.