I think you had better look again at that Zone map because I think you are making a mistake. The last time I looked, most of OKlahoma was in Zone 7b (tiny SE corner) To 6a in the NW corner I think you miss read by a factor of a whole Zone.

I would not want you to be buying plants with the wrong zone in your memory banks. There are other factors than Zonal info to take into account, because where I live and most of England is mostly Z8b but that sure does not tell the whole story. LOL. This is called the DUHH factor.

Here is a link that might be useful: Oklahoma zone map

James, If you are interested in learning more about the AHS Heat Zone Map, there was a book published in the late 1990s based on the Heat Zone maps. I believe it was called Heat Zone Gardening. I bought a copy and read it when it first was published, and really didn't learn anything new in terms of what plants would grow where I lived at the time, which was in Texas, or what would grow here, where we were building a house at the time. By then, I'd already been gardening long enough to know what would and wouldn't tolerate the heat. I do think Heat Zones could be more useful to people that either are new to gardening or are new to gardening in a specific location that is different from where they gardened before.

The problem I have with the concept of Heat Zones is that it is based on how many days a year a specific area has temperatures above 86 degrees, which is the baseline temp at which heat begins to damage plants. That probably works well for people where 86 degrees is considered hot, but what about here? I'd like to see heat ratings based on how many days a year the temps exceed 96 or (after this summer) 106 because the hotter the temps get, the harder they are on plants. Also, unless they have come back and updated the Heat Zones since they were first released, they were based on temps recorded at weather stations from the mid-1970s through midd-1990s, and I think the weather has become somewhat more extreme since then.

When I buy plants, I usually see the USDA Cold Hardiness zones listed on the tags, and sometimes, but certainly not always, the Heat Zones too. I think a lot of commercial growers have been slow to add the heat zone info to tags. I have noticed that the heat zones are used quite often in magazine articles about plants.

Wantonmara, I think y'all are talking about apples and oranges. He's referring to the American Horticultural Society's Heat Zones and you're referring to the USDA Cold Hardiness zones. Like you said, there's lots of other factors in play and I do not necessarily rely too much on these zones because our weather here does not play fair and behave as the zones indicate it ought to. Texas, Oklahoma, Kansas, Arkansas and a few other states need their own Drought Zone ratings to help us understand how much drought and heat our plants can tolerate. I'd say anything that survived this year deserves a triple-A rating or something.

Dawn

Could we be looking at two different maps? One based on frost dates and one based on days above a certain temperature?

Oops, my computer and I are both slow today

Yes,...Me bad. I know about the heat Zone map . Have for along time but it is not ingrained in me like the Cold hardiness one. I am not running on all gears today , I guess. Multitasking cooking dinner. I cow tow and will say my Hail Maries in public. LOL. To make up for this lapse I will post the right one.

Here is a link that might be useful: Heat Zone map

I will attach a link to a site with information about heat zones and also a link to a downloadable map. Heat zone and cold hardiness zones are different. Heat zones list an area by the average number of days a zone/area is above 86 degrees F. As heat affects plants. Some are more heat tolerant than others. Jay

Here is a link that might be useful: heat zones

Dawn, I completely missed that part about it being based on 86 degrees, And for us it should' as you say, be based on a much higher temp,
If that were to happen I think it could be a much more important tool for us.
I get excited when I find a new bit of information and I'm in a hurry to learn all about it. LOL

I've been on the garden forum for about three years now, and learned a lot of new things about gardening, from everyone here, and I appreciate it.
One of the most important thing to learn is where to find the information that you need, and this is a good place to start. I also read a lot and I've learned to take advantage of our local county extension center, we have some good people here that are willing to help in any way they can.
And they are willing to let you know that the other state Extensions have some very good sites also.
And I am really amazed at the amount of info, available online. of course the biggest problem there is in determining what is and what isn't worthwhile.

In the past I have always been a more traditional type of gardener, (I guess you would call it row gardening,) but I've become aware that there are better ways and I'm slowly making some changes.
This past summer has made me a bit humble, I had a lot of problems from the heat, things did not produce well at all, and Three of my young maple trees got what I believe to be Anthracnose, Oh well I'm sure next year will be better. LOL

I live in town and I find it interesting and funny at times when complete strangers will stop by to talk about the garden, some will ask the usual questions and some will want to know why I'm doing some things differently,
Why I've changed this or that.
I guess they had been watching all the time and got curious.
I've never seen anything like a garden, to bring two complete strangers togather for a friendly conversation.

Also I want to apologize if I confused anyone about the zones, I'm sure I could have worded it better if I had taken a little more time, sorry.

James.

When the heat zone book came out there were some cynical people who mentioned that selling books was the name of this "new" heat zone theory. I for one noticed right away that all they talked about was heat tolerance as if that was the only determining factor in growing plants in the summer. Well there's all types of heat and the high temperatures for instance in some desert climates is a far cry from the high temperatures PLUS humidity in most of the south. A plant that can take high temperatures may well rot when humidity is added to the heat. One of the best books still out there (if you can find it) is called Perennials for American Gardens by Ruth Rogers Clausen and Nicolas H. Ekstrom. It won't help you with your vegetables, but I wouldn't be without it if I were planning on planting ornamentals.....Maryl

I wish we would get away for using the term "NEW" in printed material. I don't think anything stays new. A diet, a book, a research paper, or anything else will be revised or become obsolete.

I much prefer to look at the date and judge for myself if it is new or not, but new seems to sell anything.