w

what zone are you? a new usda hardiness map

2012 usda hardiness map
HALF THE NATION’S 80 million gardeners will find themselves officially declared a half-zone warmer today, when the United States Department of Agriculture launches the first update since 1990 to its Plant Hardiness Zone Map. No, the new map is not technically a confirmation of a trend toward global warming, the agency says—a different set of data is used in it than in those longer-range calculations—but it is a more accurate picture of growing conditions across America, particularly in tricky areas such as mountainous ones that may have been rated too cold or too warm in previous versions. We have ever-more sophisticated computers to thank for enabling scientists to capture the more accurate take on things.

“The increase in our computing power today allows the research team to build into their algorithms things they knew were important factors in 1990, but couldn’t include,” said Catherine Woteki, Chief Scientist and Under Secretary for Research, Education and Economics for the USDA, in an interview yesterday. Factors such as elevation, the slope of land, or how close to a body of water a location is, can cause sharp variation despite close adjacencies.

“Taking those into account now provides a lot more detail,” Woteki said, “and people will be able to see islands of heat, and also cool ones, on the new map. As a scientist and a home gardener, I love seeing this so much more clearly.”

NY 2012 USDA Hardiness Zone Map
The new map is built using digital Geographic Information System technology and you’ll notice the sharper boundaries and better resolution right away when you visit its interactive website. To find out whether your zone has shifted, start here. Though I’ve always thought of myself as a Zone 5B, I’m now officially there, no longer in Zone 5A—so I’m among the half who are officially warmer. My new New York State map is above; I also looked right away at Texas, for instance, where I could see a similar shift to the warmer 50 percent (new East Texas map below).

The new Plant Zone Hardiness Map draws on data from 1976-2005—in initial calculations, adding more recent years didn’t affect the outcome—specifically 30-year averages of what are essentially extreme events (the coldest temperature of the year). Climatologists studying climate change, by comparison, look for trends in overall average temperatures over a 50- to 100-year period. The 1990 map drew on data from 1974-1986.
“This is fun,” said Woteki, “and a really a good time to have it because I just got my first plant catalog in the mail this week.” The “new math,” she says, will make for some good shopping–especially for those who find themselves in a different zone and are feeling adventurous. Indeed.

Highlights of the New Map

  • Data from a total of 7,983 stations were incorporated into the calculations.
  • Two new Zones—12 and 13, with extreme minimum temperatures of 50 and 60 degrees F, respectively—have been added to the former 10-Zone structure
  • Puerto Rico is on the map for the first time.
  • You can instantly search by your state or by zip code for your zone.
  • Though the USDA will no longer print maps for sale, you can download and print at different DPI, resulting in an instant detailed color image of the area(s) desired.
  • Completed drafts were reviewed by a team of climatologists, agricultural meteorologists, and horticultural experts—in a process Woteki charmingly calls “ground truthing”–to find errors.
  • More details on what’s new are covered here, on the map site.

Who Uses the Map?

IN ADDITION to gardeners, nurseries and plant breeders are among those who use the Plant Hardiness Zone Map most, as the data also figures into research models that include for crop-risk insurance assessment, and the spread of exotic weeds and insects.

For Canadian Gardeners

For Canadian gardeners, use the map at this site instead.

Categoriesfor beginners
  1. K.B. says:

    Oh, wow – for the first time ever, I’m in the SAME zone in both the USA and Canada (6A). Do you know how easy this has made my life?? I live right on the border (I can see the US from my house), and get plants and seeds from both countries – now, I don’t have to remember two different zones. I just have to remember which country I’m ordering from :))

  2. Chiot's Run says:

    I don’t buy it – last year we had a super cold winter – a zone colder than we are listed (zone 5) now they say we’re a zone 6. This map is hogwash – I prefer the Sunset map.

    I know they took more information into consideration for this map, but they’re still falling short. A NEW Ohio summer garden is a whole different ballgame than a Mid-Coast MAine summer garden.

    I’m also glad they at least did a more detailed version. Nothing was more annoying than trying to find your little garden when it was in between zones on the big map.

    Your best best for information is always the old-timer gardeners in the area. They’ll give you more details accounted of what you can expect to survive and thrive in your particular microclimate.

  3. I’m still in 7b, but now I’m hanging of the edge of it all Cliffhanger style. I wonder if this means I could try growing some of the citrus trees that are only supposed to be hardy in zone 8+? Maybe just throw a heat blanket on them on super cold nights??

    1. Margaret says:

      Hi, Jessie. Love it: cliffhanger style! I love playing zone-pushing games, so this new map is just going to be even more of an enabler for already naughty me, I fear. :)

  4. Jennie says:

    Thanks for pointing this out – it’s nice to be able to zoom in on places! We’ve mostly lived in mountainous regions, so I never felt they got the zones right. I’m still not sure on some of them, but some are definitely more accurate. (I just KNEW Boise was a zone 7!)

    Oh, and it says we’re in a 6a now. Sounds about right, if you exclude the extreme cold we rarely, but occasionally do get.

  5. Melanie G says:

    This is wonderful! Thank you for sharing, and for explaining :-) It’s fascinating to see how the zone can shift just a few miles down the road!

  6. JUDI says:

    It looks like my tiny space(1 acre) has been bumped up to 6a I will dig through the garden catalogs with more gusto. Thanks for the email.

  7. balsamfir says:

    Interesting, certainly more precise, and a good place to start if you’re moving to a new place and haven’t experienced winters there. I’m one of those that have their zone moved, from 3b/4a to 4b, but if over the past thirty years I’d tried to grow z4b plants, I’d have no garden now, since we’ve certainly hit even -40(no wind chill) in the past 15 years. I think the map would be more useful combined with snow pack and summer water in addition. I’m finding that in wet years, everything goes well, no matter how cold, but in drier summers, I’m fighting to keep things alive. Other wetter places around me do better with warmer zone plants. And a winter with decent snow cover is rare anymore, so the ground temperatures are colder than they might have been. I’m increasingly shopping for plants/shrubs that can weather extremes of hot and cold, since we now routinely have real heat waves that are new for this area in the summer.

  8. Abby says:

    I suspected Fort Wayne had moved a bit “south”. The spring and fall feel longer, but you still can’t set tomato plants out too soon. Thanks for this info!

  9. My running joke has always been that the line between zones 5 & 6 ran through my yard. Now with the new map I can say that it does not appear to have changed at all! There are so many micro-climates in these hills it will take more sophistication than this iteration to map it properly. It will be very helpful though, when looking at traveling to other locations, compared to the prior version.

  10. The map certainly is a thing of beauty, but when it tells me our zone is 8b and I have lost a few 7a plants in the last few harsh winters, it makes me wonder. Global warming seems to be producing more volatility and extremes of weather. Portland bloggers have been mourning the loss of things like New Zealand flax, which we used to be able to grow reliably.

  11. Jody says:

    Really? With the sophisticated algorithms they can’t update to at least 2010 or 11? Sorry, but I think that is lame! 2005? BTW – Global Warming imho is also an out dated term. I am sitting today in the Mountains of NC and it is 63 degrees out! Yet last year was fridgid. Climate change is a more accurate term. Don’t mean to be so contrary…. But I don’t think I’m buying this either.

    1. Margaret says:

      Hi, Jody — as mentioned, the additional data (beyond 2005) when figured in didn’t yield a different result in their initial calculations, so they did at first computer with it as well in preliminary rounds apparently. So in effect it’s been taken into consideration, but since it didn’t change the direction/outlines of the map, they didn’t use it in the eventual final calculations, they explained. Yes, climate change is the better term – but since the map shows half of us in a warmer zone they want to clarify that it doesn’t mean this is a global warming study (even though both phrases include WARM). Does that help? An yes, it has been 50s a lot here this “winter” after a glacial age last year and feet of snow in October. Madness.

  12. Deirdre says:

    Of course, it can’t include microclimates. I’m in a weird little cold sink, so while I should be 8b, I’m really 7b

  13. Anne Allbeury Hock says:

    Hello from the eastern shore of the Chesapeake Bay in Maryland…the Easton area.
    I don’t think this new map is very accurate…..or do they average the readings over the five or six years. We often have temps as low as 5 – 10 and once in awhile 0!!
    Also, the old map claims that the temps are the same here as Long Island. Wow! Why did I move! Someday I will live somewhere where my garden doesn’t die every year. I can’t quite believe that we are now in Zone 8. Also, does anyone ever factor in high temps. Last summer I lost quite a few things to the heat…over 100
    on and off for two weeks. This is a tough gardening location! (Sigh!) I just love this site…thanks, Margaret.

  14. kevin says:

    I have a garden in what is considerd zone 6 along the CT. shoreline.[ inland apprx. 15 miles.] The zone map should only be used as a starting point; factrs such as soil moisture content in the winter months,micro climates, and plant hardiness all dictate on how our gardens grow. Each garden in itself is a micro climate and only through trial and error do you truely learn the ways of your land,and that is what makes the challenge that much more rewarding

  15. Vicki Peterson says:

    Well living in north Idaho, I’m sticking with my old 5a rating…so far (I see I was upgraded to a 6b). Who the heck really knows? Truly the weather has been bizarre everywhere across the nation, but it still seems to settle in it’s own “niche”, I think. But, it is nice to have a base to work with in ordering plant and gardening. We probably are all very familiar with the lay of our own land, so we go from there…

  16. mihaela cobb says:

    Now we officially know but do the plants know ?! We all play plants jeopardy at one point and I can see my fellow gardeners already making lists of wanted plants that were forbidden until yesterday. The funny part will come in the spring when the nurseries will have all kinds of treasures that push the hardiness limit even further.

  17. Beth says:

    Gee, just what I needed. The Federal Government redoing the zones for gardeners. The Sunset zone maps are SOOO much more accurate still despite all the money and ‘scientific calculations’ they used. Sunset 7 vs. the newly calculated designation of 8B for our area? Give me a break! Personal experience is a better gauge of accuracy than impersonal government research, and their new designation just ain’t computin’ in my neck of the woods. So, if you Westerners love your plants, stick with Sunset!

    1. Margaret says:

      Hi, Beth. Sunset is great, isn’t it? I think the USDA put a lot into this improved map, but to be all things to a 3000-mile-wide nation with infinite elevations and pockets and whatever…hard! I always go to my state extension service (for me it’s Cornell) first — agreeing with you that the more on-the-ground local info can be, the better.

  18. Hi Margaret,

    Thanks for this detailed explanation of how the USDA arrived at this map. It now has me in Zone 6A instead of Zone 5B, but I’m not going to go by that. I know what happens when I try to grow Zone 6 plants. I’m sticking with Zone 5 when choosing most of my plants. Oh, I’ll still plant some Zone 6 things (because that’s what we gardeners do – we’re gluttons for punishment, sometimes), but if I want a plant to reliably survive here, I’ll use Zone 5 rated ones to help me choose. (Knowing this is just one criterion to consider!)

  19. Deirdre says:

    Even the high resolution map is not detailed enough. I love Sunset because it is so much more detailed then USDA. Of course, the closer you get to their office, the more detailed it is. Have you looked at their L.A. maps? Every hill has different zones on each side.

  20. Pamela says:

    As we explore new crops for our farm and plants for our nursery in The Aloha Garden of Maui, we appreciate the additional information; however, we still need more details for Hawaii as climates are very different across the island.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.