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Growing Regions and Zones

The plant hardiness zones given in this site are based upon those from the USDA provided by the United States National Arboretum.

For a full range of temperatures and example cities in an interactive map, see the following web page: USDA Interactive Map

There are many benefits and drawbacks associated with the use of hardiness zones, see the following web page for an in depth discussion: http://en.wikipedia.org/wiki/Hardiness_zone

A basic overview of average minimum temperatures associated with the zones is given in the following table:

Zone

Average Annual Minimum Temperature

Zone

Average Annual Minimum Temperature

1

< -50°F (45.6°C)

6

< -10° to 0°F (- 23.3 to -17.8°C)

2

 -50° to -40°F (-45.6 to -40°C)

7

< 0° to 10°F (- 17.7 to 12.3°C)

3

 -40° to -30°F  (- 39.9 to -34.5°C)

8

< 10° to 20°F (- 12.2 to -6.7°C)

4

 -30° to -20°F (- 34.4 to -28.9°C)

9

< 20° to -30°F (-1.2 to 40°C)

5

 -20° to -10°F (- 28.8 to -23.4°C)

10

> 30° (-1.1°C)

The table below has links to various hardiness zone maps:

Africa

Europe

Russia

Australia

Great Britain and Ireland

South America

Canada

Japan

South Africa

China

New Zealand

World

Examples of Plants that grow in Each major Growing region Zone

Growing Zone 1 plants

Plants in USDA zone 1 can survive temprerature down to -60°F (-51°C), and thus can survive extremely cold conditions. Indeed many require a prolonged cold period as part of their life cycle. As many cold climates also lack water, zone 1 plants are often tolerant of droughts too.

A typical garden plant suited to this growing region is Cotton grass. This member of the Eriophorum plant genus is able to grow in temperate through to arctic regions.

Eriophorum angustifolium
Eriophorum angustifolium (Cottongrass), Zone 1 plant photograph by Bering Land Bridge National Preserve; CC.

Growing Zone 2 plants

Plants in USDA zone 2 can survive temprerature down to -50°F (-48°C). A typical garden plant suited to this growing region is Acer negundo, also known as Box Elder.

Growing Zone 3 plants

Plants in USDA zone 3 can survive temprerature down to -40°F (-42°C). A typical garden plant suited to growing region 3 is the Crocus Plant.

Growing Zone 4 plants

Plants in USDA zone 4 can survive temprerature down to -30°F (-34°C). The Hosta plant grows well in zone 4.

Growing Zone 5 plants

Plants in USDA zone 5 can survive temprerature down to -20°F (-29°C). Members of the Canna genus should perform well in this growing region.

Growing Zone 6 plants

Plants in USDA zone 6 can survive temprerature down to -10°F (-23°C). A typical garden plant suited to this growing region is the hibiscus plant, also known as the China Rose.

Growing Zone 7 plants

Plants in USDA zone 7 can survive temprerature down to 0°F (-17°C). Coneflowers and other Rudbeckia palnts do well in this zone.

Growing Zone 8 plants

Plants in USDA zone 8 can survive temprerature down to 10°F (-12°C). Garden plants suited to this region include Peonies.

Growing Zone 9 plants

Plants in USDA zone 9 can survive temprerature down to 20°F (-7°C). The fruit tree Persimmon Fruit Trees grows well in zone 9.

Growing Zone 10 plants

Plants in USDA zone 10 can survive temprerature down to 30°F (-1°C). A typical garden plant suited to this growing region is the Geranium.

Growing Zone 11, 12, and 13 plants

Plants in USDA zone 11 to 13 can survive temprerature down to 40°F (4°C). This means that they are frost tender and will got over-winter in cold areas.

As these areas are often very hot, a plant must also be able to thrive in high heat (and often humid conditions).

Gardener's in colder areas often grow plants from warmer regions indoors or in containers (bringing indoors well before the chance of any frost.

A typical plant suited to this growing region is the succulent Agave, Check out my Agave parryi growing guide.

Agave parryi
Agave parryi (Parry's agave / mescal agave), photograph by Dr. Boli; CC.

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