Gardening zones indicate the hardiness of a geographic region to help you determine if a plant can survive the winter where you live. When you know the gardening zone of your location, you can choose the right types of crops and landscaping plants for your environment.
Gardening Zones Are Temperature Zones
The gardening zone system is officially called the United States Department of Agriculture (USDA) Plant Hardiness Zones. The USDA indicates each hardiness zone on a map of the United States. There are 13 hardiness zones. These zones are categorized according to their temperature zones.
Temperature Scales for Garden Zones USA
The gardening zones are based on the average annual extreme temperature of your region. You'll discover that most zones have around a 10°F (5.6°C) variation in temperatures. Each zone will have this 10°F (5.6°C) range, such as the Zone 7 range is 0°F to 10°F.
Cold and Warm Sub Zones
Each hardiness zone has two sub-zones (a and b). The a and b designate a 5°F temperature variance. This isn't enough to warrant a change in the zone. In these instances, the zone is divided into sub zones, a (colder) and b (warmer) areas of the zone.
Microclimates Have More Than One Zone
It isn't unusual for microclimates to have more than one hardiness zone. In fact, you may be surprised to find small microclimates in your yard or garden. You may also discover microclimates within your neighborhood or town.
How to Find Garden Zones United States
You can find your gardening zone by reviewing the USDA Plant Hardiness Map to get a better idea of your zone. Generally, the coldest part of the United States will range from Zone 1 through Zone 6. These areas have their coldest average annual temperatures in the below zero range. Zones 7 through Zone 11 will have their coldest annual average in the above zero range.
How Product Labeling Uses Garden Zones USA
Gardening suppliers for seeds, berries, trees, and plants display gardening zones on all their products. When you shop for various plants and seeds, you can check the packaging or website information to see which hardiness zone is recommended. This system prevents gardeners from choosing plants that are not hardy enough to thrive in their environments.
Temperature Considerations When Planning Gardens
Luckily, there are many varieties of ornamental and edible plants that can thrive in a wide range of environments. If you live in a gardening zone with a short growing season, the gardening zone labeling can help you choose the most adaptable plants for your climate.
Landscaping Choices by Matching With Gardening Zone
It's imperative to know which landscaping plants can survive in your gardening zone, otherwise you'll be replacing perennial garden flowers each spring. When considering plants and trees for landscaping projects, keep in mind the freezing temperature for your zone. For example, Zone 1 has -50°F to -60°F winter temperatures, while Zone 13 has an annual low of no more than 60°F to 70°F during the winter months.
Plan a Vegetable Garden for Your Gardening Zone
Your gardening zone and the length of your gardening season determine which crops you can plant. If your gardening season is long, you can often have two summer vegetable gardens. If your winter is mild, you can plant vegetables that tolerate fall and moderate winter temperatures. For colder climates, you can rely on your gardening zone as a guideline for the best vegetables to plant.
Has Climate Change Affected Gardening Zones?
Many farmers, gardeners, and growers noticed the shift in their growing seasons over the past two decades. Some report their growing season has shifted forward with a later first and last frost than in the past. The Arbor Day Foundation created a controversial hardiness zone map showing a northern shift in the zones from 1990 to 2006.
2012 USDA Plant Hardiness Update
The USDA updated the Hardiness Map in 2012 to reflect what the agency stated was additional data. However, many people claim the additional data is climate change related. What makes this controversial is the inconsistency of the temperatures that can fluctuate between normal to unusual extremes of high and low temperatures from one growing season to the next. With the USDA Plant Hardiness Map changes, most people draw their own conclusions about the reason for the changes.
Gardening Zones Are Helpful Tools
It's very helpful to have gardening zones so you can enjoy each growing season to its fullest. When you understand how to use this information, you can search for gardening tips and ideas specific to your gardening zone.