Home > Help > My Hardiness Zone

My Hardiness Zone


Climate Zone Map

Copyright 2006 by the National Arbor Day Foundation

What are Hardiness Zones?

The plant hardiness zones divide the United States and Canada into areas based on a 10 degree Fahrenheit difference in the average annual minimum temperature. (The United States falls within Zones 2 through 10). For example, the lowest average temperature in Zone 2 is -50 to -40 degrees Fahrenheit, while the minimum average temperature in zone 10 is +30 to +40 degrees Fahrenheit.

Suggested hardiness zones have been indicated for all of our plants available online. If a range of zones, for example, zones 4-9, is indicated, the plant is known to be hardy in zones 4, 5, 6, 7, 8, and 9. Suitable hardiness means a plant can be expected to grow in the zone's temperature extremes, as determined by the lowest average annual temperature.

Keep in mind that local variations such as moisture, soil, winds, and other conditions might affect the viability of individual plants.

As per our guarantee, Santa Rosa Gardens is not liable for the loss of plants sent to areas beyond their listed hardiness zones.

A note about Microclimates

Some zip codes are in small areas that are warmer or cooler than the surrounding area. These areas, called microclimates, are often associated with urbanization or steep elevation changes, and many are too small to show on our map.

If it looks on the map like your zip code should be in a different hardiness zone than the one we provide for you, your zip code is probably in a microclimate that is too small to represent on the map.

A good example of this is Lincoln, Nebraska. Several zip codes for the city of Lincoln bring up zones 5-6. The map for these zones covers all of southeastern Nebraska.

However, many zip codes for the city of Lincoln bring up zone 6. The zone 6 map does not appear to cover Nebraska at all. The reason for this is that several zip codes in Lincoln are in microclimates.

Microclimates occur in most large cities due to the urbanization effect that buildings bring about. In addition, regions of the country with bodies of water or mountains may contain "pockets." These climatic pockets mirror warmer or cooler zones than the surrounding region.



AVERAGE DATES OF FIRST AND LAST FROST NOTE:

The dates below are for the Northern Hemisphere (Adjust appropriately for Southern Hemisphere)

Zone 1
Average dates Last Frost = 1 Jun / 30 Jun
Average dates First Frost = 1 Jul / 31 Jul Note: Vulnerable to frost 365 days per year

Zone 2
Average dates Last Frost = 1 May / 31 May
Average dates First Frost = 1 Aug / 31 Aug

Zone 3
Average dates Last Frost = 1 May / 31 May
Average dates First Frost = 1 Sep / 30 Sep

Zone 4
Average dates Last Frost = 1 May / 30 May
Average dates First Frost = 1 Sep / 30 Sep

Zone 5
Average dates Last Frost = 30 Mar / 30 Apr
Average dates First Frost = 30 Sep / 30 Oct

Zone 6
Average dates Last Frost = 30 Mar / 30 Apr
Average dates First Frost = 30 Sep / 30 Oct

Zone 7
Average dates Last Frost = 30 Mar / 30 Apr
Average dates First Frost = 30 Sep / 30 Oct

Zone 8
Average dates Last Frost = 28 Feb / 30 Mar
Average dates First Frost = 30 Oct / 30 Nov

Zone 9
Average dates Last Frost = 30 Jan / 28 Feb
Average dates First Frost = 30 Nov / 30 Dec

Zone 10
Average dates Last Frost = 30 Jan or before
Average dates First Frost = 30 Nov / 30 Dec

Zone 11
Free of Frost throughout the year.