Consult a book, blog or fellow gardener for advice and you'll be met with the same question: What's your zone? You probably know that it has something to do with where you live, but where did these planting zones come from and how do you find out which one is yours?
Consult a book, blog or fellow gardener for advice and you'll be met with the same question: What's your zone? You probably know that it has something to do with where you live, but where did these planting zones
come from and how do you find out which one is yours?
The zones we use for gardening are not as much about gardening as they are about temperature. USDA Plant Hardiness Zones, as they're officially called, are based on years of average input for lowest temperatures in an area. Locations with an average temperature range of 10 degrees are grouped together to create "zones." These average temperatures are used as a guideline to determine which plants can survive in an area.
In the U.S. there are 11 zones. Zone 1 is the coldest, averaging temperatures as low as -50 F in the dead of winter. Zone 11 never really gets colder than 40 degrees F. The significance of average temperature lows is how much cold the plant can handle. For example, when a plant is hardy to zone 6, that means it can withstand temperatures as low as -10 F. This does not, however, mean you should plant certain plants at the coldest time of year; it's more of a general guideline on the climate in your area. In addition to choosing the right plants for your zone, you'll also need to consider average frost dates for your zone to know when to plant
. Since the temperature range in each zone is pretty close, frost dates by zone are also about the same, with some variations for urban or elevated areas.
Since frost dates are the main indicator for planting annuals, in a year-round sense, zones matter most for perennial plants, like trees. You wouldn't plant a palm tree in zone 1; and you wouldn't plant maple trees in zone 11. When you're buying plants from a catalog
or in a nursery
, they generally include information about appropriate hardiness zones
for the plant species.
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