There sure is. Just go to your preferences (the link is in the "About You" section in the right-hand column) and then choose the link that says "location". This has the added benefit of letting you "fill in the blanks" about your location while you're here. Those who don't know their zone can click on a link to look up their zone.
By providing your city/state, country and zone, others will know some general information that can help them to provide better answers to your gardening questions.
The link you provided does show the map with the color codes, but the table in which you check your zone color is somewhat small. Is there a way to enlarge just the color table so that it can be read alittle easier?
I know that I am in zone 7, but the drop down box to select your zone on the location page has the option of either zone 7a or 7b. The color coded map doesn't break it down beyond the number either. (unless, of course, I have overlooked something)
I suppose it is obvious by my question I don't have a clue what the difference would be either, so that would be a great help to me also!!
frogsrus, your zip code map is the old one! Now it is confusing to know where people are, you have to ask them if they are using the old or the new codes, many people won't realize it has been changed.
Here in California, there are many microclimates (as I am sure there are all over the world) so I tend to favor Sunset magazine's Zone maps for the Western US. I am not sure they have them for the Midwest or East.
The Zones are broken down into much greater detail than the USDA (which looks at average minimum temperature). For example, much of California is Zone 9 (the valleys anyway!), and doesn't get much colder than 30 degrees F in the winter (on average). Yet, winters in the Central Valley are marked by dense tule fog, and temps never going above 60 degrees F. The L.A. basin however, occasionally gets hot, dry Santa Ana winds in January/February pushing the temp up to the 80's. Same lower temperature, varied upper temperature and amount of rainfall.
Sunset's zones (which are found in the Western Garden Guide) are far more granular taking all of those things into consideration. I was Zone 8 up in Chico, CA, and now I'm Zone 24 in southern Irvine, CA. Northern Irvine is a little hotter and is in Zone 22 (I think...) and Laguna Beach, just over the hill next to the coast, is a different zone as well.
Chico's hot temps in the summer would cook the stuff I have growing here, but it's all the same to the USDA...
Okay, I'm still looking for the answer to my question... How do I know whether I'm in zone 9a or 9b. The map does not help with that. I just guested and put 9b. I'm in Denham Springs, La. Near Baton Rouge, La. Where can I find this piece of info.???
The only way to tell whether you are in the "a" or "b" part of the zone is to find out what your minimum winter temperatures have been for the last several years.
The zone system goes in 10° increments. For example I live in zone 4 which has minimum winter temperatures between -20°F and -30°F.
The "a" and "b" just split that into a "warm half" and a "cold half" of the zone. In zone 4a the minimum winter temperatures are between -25°F and -30°F and that's where I live. In zone 4b the minimum winter temperatures are between -20°F and -25°F (yeah, I know that -25°F is present in both zones; that's just a glitch in the system I guess) so 4b is 5°F warmer than zone 4a.
The minimums for zone 9 are 20°F to 30°F with zone 9a being 20°F to 25°F and zone 9b being 25°F to 30°F. (the cold side of the zone is always "a" and the warm side of the zone is always "b".)
So, to live in zone 9b, your minimum winter temperatures should not fall lower than 25°F. Remember that these are average temperatures and that in certain years you will fall below that minimum temperature, and possibly, by quite a bit.
I hope this helps.
(I hope this makes sense? I am tired. I'll have to read it tomorrow to make sure I've got this right.)
A lot of the hardiness maps show A&B for zones, I've usually just done a google search for hardiness zone map. first result was this one http://www.usna.usda.gov/Hardzone/ushzmap.html that has a&b zones shown, and when zooming in your state, has a list of cities/major towns that go into each zone to help place yourself.
Just my opinion...I don't know how useful these "zones" are anyway, whether you use the old ones or the new ones. I see them as a guide and not much else. They'll basically tell you whether a plant will survive a winter in your area, and little else. There are so many variations climactically that I wish there were other factors we could reference, such as heat indices, humidity levels, sun UV exposure intensity, snow cover, rainfall, etc that have a much greater impact on a plan's viability than just an average minimum expected temperature.
I typed 'Twilight Zone' on the search and a picture of me came up? How is that? I'm confused, why did I come into the kitchen anyway? Have you seen my sunglasses? I guess my zone denial is really getting the best of me.
It would be nice if the USDA would more clearly define the zones, ask anyone around here and they'd say we are 7a but the all knowing government says we're 6b. I think the Sunset chart is closer to the money than the USDA. Granted we have our moment in the winter, it is either mild or cold. This past winter we had 20" of snow on Dec. 24th (very rare) and on Jan 1st it was 71* then it was cold again ... yoyo weather. Oh well maybe one day in the far off future we will figure it out.