Climate zones are areas of the world with the same levels of rainfall, humidity, and temperature.
The world can be divided into many different climates:
and so on.
A plant that does well in one climate may not do well in another.
For example, let's take zone 7.
In the United States, zone 7 corresponds to places as diverse as northern California (mild and wet, temperate), southern Nevada/northern Arizona (hot and dry, desert), and northern Georgia (hot and humid). There is no way a plant that likes northern California would ever survive in southern Nevada without a lot of watering!
(Apologies to those living in other countries -- hopefully you can see the limitations on planting zones based solely on minimum average temperature.)
This very interesting and in-depth article on climate types may help you understand the difference between temperature and climate.
Climate maps attempt to divide an area into planting zones that correspond to their climate.
If you look at the areas we have just been discussing, you'll see that southern Nevada is listed as desert, while northern Georgia is listed as temperate -- but on the hardiness zone map they are both zone 7.
Here's an interactive global climate map from HowStuffWorks.com:
If you can't see the map, click here to visit the map page on howstuffworks.com.interactive climate map of Australia with planting help for each month of the year.
Sunset Magazine (a southwestern US gardening magazine) has developed a climate zones map for all 50 states, taking into account a variety of factors including rainfall, heat days, and so on.
If you live in the US, you can use this interactive map to find your Sunset zone and suitable plants for it. (click on the map to see your area's Sunset zone)
Unfortunately, most nurseries, websites, and books don't reference Sunset zones, but you can consult the Sunset website or one of their publications if you need more information.
Anyone who has been gardening for a while will tell you that over the past ten years, their weather has been changing! And while weather is not the same as climate, changes in climate will cause definite changes in weather patterns.
Changes in climate can affect your garden in various ways:
In light of these, it's best to take these maps of climate zones as guidelines to help you learn about your garden's planting zones. Use your own experiences and the advice of your local agricultural office or county extension for guidance as to what and when to plant.
Would you like to talk about climate with others who love edible gardening as much as you do? Join the Tasteful Landscape community by filling out the form and following the instructions:
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