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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? - Nature Hills Nursery

Charlotte Weidner |

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?

Growing zone 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.


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.

growing zones green

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.

where to find grow zone

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.

growing zone once zip code is entered

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!

Plant Highlights

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.

high chill and growing zones

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!

full sun

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.

Filters for categories

Keep Your Zone Safe

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.

Plant Sentry

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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Frequently Asked Questions

What is a growing zone and how do I find mine using my zip code?

A growing zone is a geographic classification system created by the USDA that determines which plants will survive in your area based on average annual minimum winter temperatures and maximum summer highs. The zones range from Zone 1 (coldest Arctic regions) to Zone 12 (subtropical areas), with lower numbers indicating colder climates. You can find your specific growing zone by entering your zip code on NatureHills.com, which will show you exactly which plants are recommended for your area's temperature ranges and climate conditions.

Can I grow plants outside my hardiness zone?

While you can attempt to grow plants outside your hardiness zone, success rates drop significantly as plants may not survive your area's temperature extremes. Plants rated for zones colder than yours will likely thrive, but those requiring warmer zones may suffer winter damage or death. Your best bet is to stick within your USDA zone range or choose plants rated for one zone colder than yours for reliable long-term success.

Why do some plants thrive in my zone but fail for others in the same area?

While USDA hardiness zones provide excellent general guidance based on average minimum winter temperatures, they don't account for microclimates created by factors like elevation changes, proximity to bodies of water, urban heat islands, or protected areas near buildings and structures. Two properties just miles apart in Zone 6 might experience significantly different conditions—one sheltered location could successfully grow Zone 7 plants while an exposed, windy area struggles with standard Zone 6 varieties. Your specific soil drainage, sun exposure, and local weather patterns also play crucial roles in plant survival beyond the basic temperature ranges. Check your exact microclimate conditions and choose plants rated for one zone colder than your official designation if you're in an exposed or challenging location.

How does my growing zone affect planting times and frost dates?

Your growing zone determines your area's average last spring frost and first fall frost dates, which directly impact when you can safely plant. For example, Zone 3 areas typically see last frosts in late May and first frosts by mid-September, while Zone 9 regions may have last frosts in February and first frosts not until December. These frost dates tell you when to start seeds indoors, transplant seedlings outdoors, and when tender plants need protection. Check your local extension office for specific frost dates in your zone to plan your planting calendar accordingly.

What vegetables and herbs are best for my zone?

The best vegetables and herbs for your zone depend on your specific USDA hardiness zone's temperature ranges and growing season length. Cold-hardy vegetables like kale, Brussels sprouts, and carrots thrive in zones 3-6, while heat-loving crops such as tomatoes, peppers, and basil perform best in zones 7-10. Most herbs like rosemary and thyme are perennial in zones 7 and above but require annual replanting in colder zones. Enter your zip code on our website to see which vegetables and herbs are recommended for your specific growing zone.

Should I choose perennials rated for my exact zone or one colder?

Choose perennials rated for at least one zone colder than your area to ensure reliable winter survival. For example, if you're in Zone 6, select plants rated for Zones 5-6 or colder for best results. Plants rated exactly for your zone represent the absolute limit of their cold tolerance, meaning an unusually harsh winter could kill them. Stick with plants rated one zone colder to guarantee they'll return each spring.

How do microclimates like elevation, slope, or proximity to water change my effective zone?

Microclimates can shift your effective growing zone by 1-2 zones warmer or colder than your USDA designation. Elevation changes of 1,000 feet typically drop temperatures by 3-5°F, while south-facing slopes and proximity to large bodies of water can create warmer conditions that extend your growing season by 2-4 weeks. Urban heat islands often push city gardens into a zone warmer than surrounding areas. Observe your specific site conditions and consider plants rated one zone hardier or less hardy than your official zone based on your microclimate factors.

Why has my hardiness zone changed with the new USDA map?

Hardiness zones change on updated USDA maps because they reflect new climate data and temperature patterns collected over decades. The most recent 2012 USDA map incorporated 30 years of weather data (1976-2005) and showed that many areas shifted to warmer zones compared to the previous 1990 map. Zone boundaries also became more precise with improved mapping technology and additional weather stations. Check your current zone on the latest USDA map and adjust your plant selections accordingly, as you may now be able to grow plants that previously weren't recommended for your area.

Can I push plants beyond their zone limits with protection like mulch or row covers?

Yes, you can often push plants one zone beyond their limits using winter protection methods. Thick mulch (4-6 inches), burlap wraps, and row covers can help marginally hardy plants survive temperatures 5-10°F below their typical zone range. However, success varies greatly with microclimates, snow cover, and winter duration in your specific area. Start with less expensive plants to test their tolerance before investing in costly specimens outside your recommended zone.

What other factors besides zone matter for plant success, like soil or precipitation?

While USDA hardiness zones focus on temperature extremes, successful plant growth also depends on soil pH, drainage, annual precipitation, and humidity levels. For example, a Zone 6 plant may struggle in clay soil with poor drainage even if temperatures are suitable, or desert plants may fail in humid southeastern climates despite matching zone requirements. Microclimates created by elevation changes, nearby water bodies, or urban heat islands can shift your effective growing zone by 1-2 zones. Always research your specific soil conditions and local rainfall patterns before selecting plants for your landscape.

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When ordering a tree or plant, make sure to know your planting zone.

You can determine your garden's USDA hardiness zone by entering your Zip Code below.