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Hardiness Zones and Planting Information

What are hardiness zones?
It seems every gardening book and nursery catalog refers to plant hardiness zones, also known as climate zones or growing zones. If you're new to gardening, you may be wondering what all the fuss is with these zones, and how to find out which zone you are gardening in.

Basically, plant hardiness zones are a guide to help you know which plants will grow where you live, so you don't plant things that will soon die just because they can't manage your region's temperatures. Plants vary in the temperature extremes they can endure. Basic laboratory testing can determine the lowest sustained temperature a particular plant type can withstand, but, as gardeners, we still need to know how these measurements relate to our own gardens.


Hardiness Zones -- Details
Zone Color Key Zones 2-10 in the map have been subdivided into light- and dark-colored sections (a and b) that represent 5 F (2.8 C) differences within the 10 F (5.6 C) zone.  The light color of each zone represents the colder section; the dark color, the warmer section.  Zone 11 represents any area where the average annual minimum temperature is above 40 F (4.4 C).

The map shows 20 latitude and longitude lines.  Areas above an arbitrary elevation are traditionally considered unsuitable for plant cropping and do not bear appropriate zone designations.  There are also island zones that, because of elevation differences, are warmer or cooler than the surrounding areas and are given a different zone designation. 

Note that many large urban areas carry a warmer zone designation than the surrounding countryside.  The map-contains as much detail as possible, considering the vast amount of data on which it is based and its size.








If you live outside North America
You can roughly translate the USDA hardiness zones by finding out how low your area's temperatures can reach, and then use the chart below to find your corresponding zone.

Zone 1: below -46 C (below -50 F)
Zone 2: -46 to -40 C (-50 to -40 F)
Zone 3: -40 to -34 C (-40 to -30 F)
Zone 4: -34 to -29 C (-30 to -20 F)
Zone 5: -29 to -23 C (-20 to -10 F)
Zone 6: -23 to -18 C (-10 to 0 F)
Zone 7: -18 to -12 C (0 to 10 F)
Zone 8: -12 to -7 C (10 to 20 F)
Zone 9: -7 to -1 C (20 to 30 F)
Zone 10: -1 to 4 C (30 to 40 F)
Zone 11: above 4 C (above 40 F)

Map of Hardiness Zones for Europe (off site link)

Map for Hardiness Zones of Australia (off site link)

Map of Hardiness Zones for China (off site link)

Converting Fahrenheit into Celcius or the opposite