What's a Growing Zone and Why do You Need My Zip Code?

What's a Growing Zone and Why do You Need My Zip Code?

Growing zones header

This growing zone map of the United States shows the major USDA planting zone classifications that provide averages for each area based on the temperatures each area of the country tends to experience in a usual year. 

Planting zones are used as guidelines to determine the hardiness and survivability of various trees and plant species within each geographic area in the US. While there are microclimates and elevation changes that are not accounted for in these hardiness zones, the general ranges of temperature give you a good idea of how well a plant will survive your area's immediate climate and weather.

What are the growing zones in the US? USDA Map

Hardiness zones are based on local climate, and the USDA determined the zones using average annual minimum winter temperatures and annual maximum summer highs, in each region. Ranging from the coldest Arctic Zone 1 all the way to the subtropical Zone 12, the US spans an immense range of climates and microclimates.

On this scale, the lower the growing zone number assigned to your area, the lower the average temperatures are recorded for the assigned region. While there is no "standardized" system used to determine which plants work best in the USA, the USDA's Hardiness Zone Map is the most commonly used. growing zones listed

When looking at a plant on the NatureHills.com website, you’ll see that a plant's recommended zone range is displayed and is based on the temperatures it can withstand and would expect to see in its native conditions and native habitat.

Know Your Zone

Based on the United States Department of Agriculture's Plant Hardiness Zone Map, each part of the United States is assigned a "growing zone" to help gardeners and growers determine which plants, trees, and shrubs will work best in their region.

When ordering a tree or plant, make sure to know your planting zone. On NatureHills.com, we do our best to provide an accurate listing for each product’s recommended zone. You can determine your garden’s USDA (United States Department of Agriculture) hardiness zone using this map or by entering your zip code in our Find Your Growing Zone section on each plant's page just above the Plant Highlights section.

Find your growing zones

I Know My Zone, Now What?

Once you’ve entered your zip code you’ll find out your growing zone which will be a number and a letter ‘a’ or ‘b’. A-zones are a bit closer to the next lower growing zone occasionally, while B zones tend to lean a bit closer to the next higher zone. For example, if your growing zone is 5a, then your area may experience potential zone 4b weather on particularly bad winters, while zone 5b may occasionally experience zone 6a summers or highs. Elevation can also make your growing zone cooler the higher you go and pockets or ‘microclimates’ can also influence your area's average temperature range. For specific information, you can always contact your local County Agricultural Extension Office for pinpoint information. 

Finding your zones

Knowing your growing zone (again using 5a for example) means that if you see a plant with a zone range of 3-9, then your growing zone is well within that threshold and will do great! If your zone 5a and you see a zone 5-9, you are still in that threshold, however, if you know your area tends to receive extreme temperature swings, or drastic sudden and unseasonable winter weather, it may be best to find a plant that includes one zone lower, just to be on the safe side! 

Again, your County Extension office is an invaluable resource for you to determine if that plant will survive, or if there is a cultivar that may do better.

Get In the Zone! indoor growing zones

It’s unwise to purchase a plant for the outdoor garden that cannot survive in your zone. The chances of a hot summer or especially cold winter will surely be its demise. Some like citrus trees and other subtropical and tropical plants can be used indoors during the cold months, but many plants won’t do well in the indoor setting and may need to be in a greenhouse for best health.

In many cases involving flowering and fruiting plants, such as Lilacs and Apple Trees, etc., the growing zone also indicates the chill hours needed by a plant to set flowers and fruit. These chemical cues are triggered by temperature and if a tree or plant doesn’t receive those continuous hours of chill, just won’t flower. So planting a Lilac in a growing zone that’s too hot, you may have a beautiful green shrub, but never see a single blossom.

chill hours

What is the best growing zone?

While there isn’t one growing zone better than another and plants all have their own preferences, most plants seem to do well in the more temperate zones between 5 through 8 where winter temperatures are not the most frigid and summers are not horribly sweltering. 

For the most successful planting and bang for your buck, not to mention the best flowering and longevity for your plants, shrubs or trees, always choose plants that include your growing zone in their favored range and the rest will be easy!

Other categories besides zone

However, planting a species in its recommended zone does not guarantee it will thrive. A good location is only the beginning. Once you’ve established that the plant will survive well in your growing zone, be sure you also match that plant's requirements for sun, moisture, soil type, drainage and moisture needs.

But don’t let all this overwhelm you! 

When selecting a plant, either in our category pages or by a keyword search, you’ll find an entire section for you to narrow down those plants to suit your individual needs! You’ll even be able to toggle the height and width of your plant at maturity, bloom color, bloom period and even price range.


Keep Your Zone Safe

Plant sentry logo

Another way Nature Hills keeps your region safe is with Plant Sentry™ to ensure we remain compliant with all state Agricultural laws and regulations which protect sensitive areas from invasive plant material or destructive pests and diseases. 

Once you’ve entered your zip code, Plant Sentry™ alerts you when that plant is restricted in your state or county. This heads-up will appear both on that plants information page and in your shopping cart. Don’t hesitate to reach out to our experienced customer service representatives for help finding another size container, a similar variety, or alternative that doesn’t have restrictions in your state.

Before any plant can cross state lines it is inspected and shipped at the right time to avoid invasive larvae, eggs, seeds , fungi or even bacterial issues from crossing into your area and becoming an issue for native flora and fauna.

Your County Extension Office and our knowledgeable horticultural staff are here to help you find the perfect plant for your needs, your climate and your home landscaping! So head over to Nature Hills or call us for more information!

As always, Happy Gardening!

Check out Nature Hills Terms of Service for information regarding our shipping policies, about purchases outside the recommended USDA growing zone range, and to learn more on how we go above and beyond to keep you, your plants, and our environment safe!

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