Climate zones in North America

richardb · #1 10-03-2009, 03:27 PM

For the benefit of overseas members, could someone please explain the "climate zone" numbering system in North America. Although maps show positions of States and Towns, other geographical factors must influence different regions, so it is very difficult for us overseas people to get a feel for whether we can input to a discussion.
Thanks

fotofashion · #2 10-03-2009, 05:59 PM

Exacerbating the problem also is the existence of "micro climates" which may allow a plant to be grown in one place whereas just a short distance away it would not thrive. It really is a matter of experimentation in many cases. Even in one's greenhouse there are micro climates. Oak Hill nurseries sends a care sheet when one buys a Ghost Orchid and describes the micro climate they maintain in the area where they keep their parent Ghost Orchid plants.
The amount of sun or shade, the humidity, the wind, all contribute to the mix.
Then, too, the zones are divided into A and B to further complicate the problem. Where I live the division is an east-west highway for the most part. And there IS a difference in the climate to a certain extent.
There is also another system used here, Sunset, I think. I have no idea just how that one works.
Have I helped or hindered?
Beverly A.

Alice-NJ · #3 10-05-2009, 04:06 PM

It's mostly a general reference to the climate in each zone. It gives you a rough idea that someone like me in zone 6 has lots of different issues to deal with than someone farther south in zone 9 or farther north in zone 3. As fotofashion says, each zone is broken down even further to A and B. And even though I'm in zone 6, someone in south Jersey can grow rosemary much farther into the season than I can. Many gardeners try to push the limit in their zones and often get away with growing something that's not supposed to grow there.

If you sort of look at it as that zone 6 is in the middle and temperate and the farther north you go the cooler it gets, and the farther south you go the
warmer and more humid it gets. Then the move is to the west, and the warmer and drier it gets until you get closer to the pacific. The zones are not exact, just general growing guidelines.

Kentucky · #4 10-08-2009, 06:16 AM

The USDA climate zones are general guidelines as to what will grow outdoors successfully in various sections of the United States. They refer ONLY to the expected low temperatures in winter and are therefore pretty general in usefulness. For examples, in Zone 6, a low winter temperature of 0 to -10 degrees F is expected but over the entire region of zone 6 it is very probable to occur in some areas and less likely in others. In zone 7 the expected lows are 0 to +10 degrees F. As mentioned, there are spots of higher and lower zones within the primary zone boundaries so you can often grow or not grow expected vegetation within a zone.

Zones are no longer broken down into A and B. Such divisions were far too narrow for such a general guide. The American Horticultural Society now publishes a heat zone map since the USDA map has nothing to do with heat expectations. These zone maps are only of general usefulness and much depends on the severity of a given winter.

richardb · #5 10-13-2009, 03:02 PM

Thanks for that input everyone. I understand how you must all cater for special conditions within each zone - here in the UK we are tiny by comparison so although we do not have such a variance of "zones" we do have pockets of one thing or another.
Does anyone know where I can see a zone map? It would be really helpful in trying to understand some of the comments on this forum.
Richard

Alice-NJ · #6 10-13-2009, 04:05 PM

This map seems pretty good:

http://www.mailordergardening.com/ha...FZJM5QodzReMiw

richardb · #7 10-14-2009, 03:32 PM

That is really helpful. Many thanks Alice. At least I can now get some idea about growing areas when correspondents give either their State or zone number.
Richard

raybark · #8 10-15-2009, 10:06 AM

...except, of course that most of us growing orchids do so indoors over the winter or in greenhouses, rendering USDA zones as not applicable.

hainiaBrorm · #9 12-20-2009, 09:49 AM

Hi all,

Ive been having an issue with my climate control blasting full hot, then full cold, then full hot, etc. I ran the diagnostic and it came back with problem code -26. From what I gather, there is a short in my hot/cold air mix motor, but I have no idea where the motor is located, or what wires I need to check.

Any suggestions?

mfkuwa@earthlink.net · #10 01-08-2010, 03:48 AM

I am coming late to this discussion, but to get back to richardb's original query, US climate zones are really not reliable guides to anything having to do with growing plants other than winter hardiness. They refer solely to the minimum average temperature in the winter. I live in Seattle in the Pacific Northwest of the US where we are zone 8. I have a friend in Savannah, Georgia which is also zone 8. Minimum winter temperatures are the only thing that our climates have in common. Seattle is almost as far north as you can go in the US. We have long days in the summer and short days in the winter but, because of prevailing winds off the Pacific, we have mild, wet winters and pretty mild and dry summers. Savannah being much further south has less variation in day-length. Their winters may get as cold as Seattle, but they can also have extended periods in the 70s and 80s. They also get more periods of sunshine than we do. In Seattle, in the summer, the temperatures are in the 70s and 80s and it is relatively dry. In Savannah the summers temps run frequently into the 90s and 100s and it is very humid and there can be a lot of rain.

In other words, climate zones are useless when it comes to assessing the needs of orchids being grown in a particular region. It is more useful to determine where an orchid is being grown in regards to latitude since that will determine how much light a plant is getting at a given time of year and the relative intensity of that light.

Hope this helps.