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Case Study: What is Hardiness Zones? & How Does It Help In Gardening

Picking up a plant or tree to nurture might be tricky. Coming from nurseries, most of them could not easily adapt to the environment and easily wilt. With proper education of the plant name alongside its care instructions, the hardiness zones should also be considered as a key factor to maintain its longevity.

What are these Hardiness Zones?

A hardiness zone is derived from an average annual extreme minimum temperatures across a 3-decade period. However, this is not based on the lowest recorded temperature in a region or predictions of temperature drops in the future.

Upon choosing a plant that best suits the climate within the certain place, the Hardiness Zones helps determine which option will grow best in a certain area.

The USDA Hardiness Zone Map divides North America up into 11 separate planting spots. Individually, these planting zones are situated around 10 degrees Fahrenheit colder or warmer than the adjacent zone during an average winter time.

Comparing Eastern and Western Zones

  • Eastern Zones of USDA Map

Eastern Zone is a comparatively flat area, easily mapped out by drawing lines approximately parallel to the Gulf Coast around every 120 miles progressing northward. The grid will commence tilting northeast to the Eastern Seaboard.

Given the USDA map versatility and its most recent update last 2012; it takes into consideration the accounts for special climates brought about by the Appalachian mountain regions and the Great Lakes breeze.

  • Western Zones of USDA Maps

Phenomenon like winter lows, variations of geographical elevation and frequency of precipitation determine the growing climates in western North America, and its fluctuation. The weather in the west is influenced by the Pacific Ocean, lessening its humidity as it circulates mountain ranges westward.

The growing climate in the west varies significantly from the east, where countries in similar zones can grow the same plants in the similar climates. The weather and plants that can be grown in coastal Seattle are much different than expected in the elevated and inland Tucson, Arizona despite the fact that both cities mentioned belonged to Zone 8 of USDA Map.

To find the zone of your residence, see it here.

Other Factors that are not within the scope of the Hardiness Zone Map

Given that the map is only reflecting the average of temperatures, it is not accountable for sudden thermal changes and weather unpredictability.

The variations of wind levels, soil dichotomies, amount of moisture, pollution, humidity, sunshine, and snow are major factors that affect plant survival and adaptability.

Microclimates present from one area to another, highly observable in mountain regions and pockets of wind blowing from different directions are also not included within the scope of Hardiness Zone Map, as microclimates exist in one place with one adding or cancelling the effect of another.

The manner it is planted, the location, the plant size and overall health are also things to consider.

For more information on how to use the Hardiness Zone Map for gardening, an in-depth discussion is here 72tree.com/trees-shrubs-usda-hardiness-zone-map/.


Celine Kate Trinidad is a blogger who loves to DIY home maintenance, recycling crafts, and horticulture. She has a knack for anything that needs construction, designing, and cleaning – making her the hands of the house.



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