Climate Zones In Edible Gardening

 What Are Climate Zones?

 Climate zones are areas of the world with the same levels of rainfall and temperature.

The world can be divided into many different climates:

• hot and dry (desert)
• hot and humid
• hot and wet (tropical)
• cold and dry
• cold with lots of precipitation (rain in summer, snow in winter)
• moderate temperatures with variations in rain/snowfall (temperate)
  

and so on.

A plant that does well in one climate will not necessarily do well in another.

For example, let's take USDA plant hardiness 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 that 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

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 is a very general set of climate maps for Australia.

Sunset zones

Sunset Magazine has developed a climate map for the US, taking into account a variety of factors including rainfall, heat days, and so on.

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.

Climate change and your edible garden

Anyone who has been gardening for a while will tell you that over the past twenty 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.

Here is a time-lapse global climate map showing climate changes over the past 40 years, with estimation of future climates.

Changes in climate can affect your garden in various ways:

• change in temperature (up or down), which can lead to your garden being in a different plant hardiness zone
  
• change in frequency of storms, such as hurricanes, tornadoes, blizzards, monsoons, and so on
• increase or reduction in rainfall amounts
• changes in pests and weeds as nature adjusts to the changing conditions.
  

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.