This map was created by the U.S. Department of Agriculture (USDA) Agricultural Research Service (ARS) who has recently (2012) completed an extensive updating of U.S. Hardiness Zones based upon data from 5,000 National Climatic Data Center cooperative stations across the continental United States.
The USDA Hardiness Zone Map is a map with regions defined by a 10 degree Fahrenheit difference in the average annual minimum temperature. This map divides North America into 11 separate zones. The higher the zone number, the warmer the area.
Information from the zone map helps gardeners to compare their garden climates and determine what plants will grow in their area. Keep in mind, this map only shows average annual minimum temperatures and doesn’t take into consideration important factors like soil types, rainfall, daytime temperatures, day length, wind, humidity and heat.
Those factors are very important and play a key role in healthy palm growth and development. Knowing your hardiness zone is just not enough. A good example would be Portland, OR and Austin, TX. Even though they are both located in the Zone 8, their climates are dramatically different.
Palm Trees by State
Find out what palm trees can grow in your state:
Applying zone references
In the palm profile you might have seen reference to zone or range of zones. If a palm is hardy to zone 7, that means it can withstand lowest temperatures of that zone. If there is a range of zones like 7-10, that means it can grow only in those zones and will not tolerate colder or warmer temperatures.
If you live in a microclimate, that is an area with slightly different climate from a general climate of a region, then you might be able to grow more/less palms in your garden. Even within a city, a street, or a spot protected by a warm wall in your own garden, there may be microclimates that affect how plants grow.
Here is a list of zones with avg. annual low temperatures:
- Zone 1: below -50 F (below -46 C)
- Zone 2: -50 to -40 F (-46 to -40 C)
- Zone 3: -40 to -30 F (-40 to -34 C)
- Zone 4: -30 to -20 F (-34 to -29 C)
- Zone 5: -20 to -10 F (-29 to -23 C)
- Zone 6: -10 to 0 F (-23 to -18 C)
- Zone 7: 0 to 10 F (-18 to -12 C)
- Zone 8: 10 to 20 F (-12 to -7 C)
- Zone 9: 20 to 30 F (-7 to -1 C)
- Zone 10: 30 to 40 F (-1 to 4 C)
- Zone 11: above 40 F (above 4 C)