GARDENING FACT SHEET:
What is a Plant Hardiness Zone?
The 2012 USDA Hardiness Zone Map divides North America into 11 growing
zones; each zone 10 degrees F warmer (or colder) than the adjacent zone.
These zones are further subdivided into a 5 degree F zone with an (a) or (b)
The Tri-Lakes area is assigned Zone 5b, with an average annual minimum
temperature of -15 to -10F. The lower the number, the colder the average
Zone maps were created so gardeners had a way to compare their garden
climate with the climate where a plant is known to grow. If you want a
perennial, shrub, or tree, to survive and flourish, the plant must tolerate the
year-round conditions in your area.
Zone maps are not absolute – several factors, such as elevation, soil, humidity,
shade, sun, wind, and exposure, can affect your specific gardening zone, or
even different spots within your gardening zone. These are called
microclimates – a small but distinctly different climate within the larger
climate. For example, a sunny, southern, exposure that is protected from the
wind, will be significantly warmer for most of the year than the rest of the
garden. This area may be able to sustain plants that are one zone higher
because of the microclimate. Likewise, an area on the north side of the house,
which receives no direct sun in the winter, may be one zone lower.
It is important to understand what your specific microclimates are, if any, and
Click to View Printable PDF file: “What is My Plant Hardiness Zone”