What Are Planting Zones? A Smart Grower’s Guide to the USDA Growing Zone Map
The USDA Plant Hardiness Zone Map will help you identify what to plan in your garden.
If you're serious about gardening or growing your own food, understanding planting zones—also known as USDA hardiness zones or gardening zones—is essential. These zones provide a scientific framework for identifying which plants are most likely to thrive in a given geographic location, based largely on average minimum winter temperatures.
Whether you're planting vegetables, shrubs, or trees, knowing your USDA growing zone map helps you make smarter plant choices, reduce the risk of cold damage, and maximize your garden’s success.
What Are the Planting Zones?
Planting zones are geographic areas defined by specific temperature parameters that help determine plant survival prospects. These zones serve as a standardized system to assess which plants are best suited for cultivation in particular regions based primarily on their ability to withstand local winter temperatures. A plant's hardiness refers to its capacity to survive adverse growing conditions, particularly cold temperatures that can damage or kill vulnerable species.
The primary purpose of planting zones is to provide gardeners, landscapers, and agricultural professionals with a reliable guideline for selecting appropriate plants for their specific locations. This knowledge is especially crucial when purchasing plants online or from catalogs, as it helps avoid investing in species that are unlikely to survive in your local climate. Without this critical information, gardeners would struggle to determine whether their climate suits tropical plants like birds of paradise or whether it provides the necessary winter chill period required by species such as tulips, apples, or lilacs.
The Significance of Plant Hardiness
Plant hardiness fundamentally measures a plant's ability to endure challenging growing conditions, including drought, flooding, excessive heat, and particularly cold temperatures. The genetic makeup of plants significantly influences their survival capabilities under specific environmental conditions. When a plant is described as "hardy to zone 10," this indicates it can withstand minimum temperatures between 30 to 40°F (-1.1 to 4.4°C). Understanding these tolerance thresholds helps gardeners make informed decisions about plant selection.
The USDA Plant Hardiness Zone System
The United States Department of Agriculture (USDA) Plant Hardiness Zone Map is the most widely recognized and utilized system for categorizing climate zones for plant cultivation. This system was initially developed in the 1920s and 1930s, though the first official maps weren't published until 1960. Since then, the USDA map has undergone several revisions to incorporate updated weather data and account for climate change.
Structure and Organization
The USDA system divides North America into distinct zones based on average annual minimum winter temperatures. The complete USDA scale encompasses 13 zones, with Zone 1 representing the coldest regions and Zone 13 the warmest. Within the continental United States, these zones typically range from Zone 3 to Zone 10.
Each zone represents a 10-degree Fahrenheit difference in average annual minimum temperature. For greater precision, zones are further subdivided into "a" and "b" segments, each representing a 5-degree Fahrenheit increment. For example:
Zone 4 spans temperatures from -30°F to -20°F (-34°C to -29°C)
Zone 4a specifically covers -30°F to -25°F (-34°C to -32°C)
Zone 4b covers -25°F to -20°F (-32°C to -29°C)
The USDA map uses a color-coding system to visually represent the temperature gradient across regions.
Plant Hardiness Zones by U.S. Region
The USDA further categorizes gardening zones based on geographic regions across the United States. These regions include the North Central, Northeast, Northwest, South Central, Southeast, and Southwest. Below is an overview of each, including the states they cover, the USDA zones they span, and their general climate characteristics.
North Central
This region typically experiences cooler overall temperatures throughout the year.
Zones: 2 to 5
States: North Dakota, South Dakota, Minnesota, Wisconsin, Nebraska, Iowa, Illinois, Kansas, and Missouri
Northeast
The Northeast features a wide range of temperatures and includes multiple hardiness zones.
Zones: 1 to 7
States: Michigan, Indiana, Ohio, Kentucky, Virginia, West Virginia, Pennsylvania, New York, New Jersey, Maryland, Delaware, Connecticut, Massachusetts, New Hampshire, Maine, Vermont, and Rhode Island
Northwest
In the Northwest, winters are typically wet, while summers tend to be dry and mild.
Zones: 3 through 9
States: Washington, Oregon, Montana, Idaho, Wyoming, and the northern portion of California
South Central
This area stretches from the southern plains down to the Gulf Coast and has a generally warm climate.
Zones: 6 to 9
States: Portions of Texas, Oklahoma, Arkansas, Louisiana, Mississippi, and Alabama
Southeast
In this region, the final frost usually occurs in April. Notably, South Florida typically does not experience frost at all.
Zones: 7 through 10
States: Tennessee, North Carolina, South Carolina, Mississippi, Alabama, Georgia, and Florida
Southwest
Known for its intense summer heat, the Southwest also sees considerable variation in winter lows.
Zones: 3 to 10
States: California, Nevada, Utah, Colorado, Arizona, and New Mexico
Popular Plants to Grow by Region and Zone
There are many plants that thrive in each zone, but here are some of our favorites for each.
North Central (Zones 2 through 5)
| Category | Recommended Plant |
|---|---|
| Groundcover | Creeping thyme (Thymus serpyllum) is a low-maintenance groundcover that thrives in zones 2 through 9. Produces fragrant spring flowers and grows best in well-drained soil with full sun. |
| Vine | Clematis is a climbing plant with dainty, beautiful flowers. It grows well in various conditions across zones 3 to 9. |
| Perennial | Coneflowers (Echinacea) are native to the region and attract pollinators. They prefer full sun, well-drained soil, and grow in zones 3 through 9. |
| Shrub | Lilac (Syringa) is an heirloom shrub for zones 2 through 8. It produces fragrant spring blooms and thrives in full sun and well-drained soil. |
| Tree | Red maple (Acer rubrum) is a fast-growing, adaptable tree that grows well in zones 3 to 9. Plant in spring or fall. |
Northeast (Zones 1 through 7)
| Category | Recommended Plant |
|---|---|
| Groundcover | Sweet woodruff (Galium odoratum) grows best in part shade. "It usually grows 10 to 12 inches high with a spread of 18 to 20 inches," Speight says. This plant loves damp borders and produces tiny white blooms with green foliage. Best for zones 3b through 7. |
| Vine | Clematis thrives in the Northeast. "Great for zones 4 through 8, this vine loves a full to part sun environment," says Speight. "A little compost or aged manure in the spring will keep this plant well fed." Use mulch to keep the roots cool. |
| Perennial | Hellebore (Helleborus) is a dependable perennial best for zones 3 through 8. "One major reason I love this plant is the upkeep is minimal," says Speight. Cut back old foliage in early spring for new blooms. Flowers start in January and continue through May. |
| Shrub | Osier dogwood (Corns sericea) performs well in full sun to part shade. "The beauty of this shrub is revealed when pruning out old growth," says Speight. New stems grow red or coral, perfect for winter contrast. Thrives in zones 3 through 8. |
| Tree | Redbud (Cercis canadensis) is a low-maintenance native tree ideal for zones 4 to 9. "From the prolific pink blooms to the heart-shaped leaves, what’s not to love?" says Speight. Tolerates clay to loamy, well-drained soils and partial or full sun. |
Northwest (Zones 3 through 9)
| Category | Recommended Plant |
|---|---|
| Groundcover | Black Scallop bugleweed (Ajuga reptans 'Binblasca') thrives in zones 3 through 9. Known for glossy foliage and blue flowers. |
| Vine | Climbing hydrangea grows in zones 4 to 8. Prefers rich soil and tolerates full sun to deep shade. |
| Perennial | Coneflowers (Echinacea) thrive in zones 3 to 9. Bloom through summer and add vibrant color to gardens. |
| Shrub | Boxwood (Buxus) grows in zones 5 to 9. A deer-resistant, fragrant evergreen shrub. |
| Tree | Evergreens are well-suited to the Northwest’s cool, moist climate and maintain foliage year-round. |
South Central (Zones 6 through 10)
| Category | Recommended Plant |
|---|---|
| Groundcover | Creeping phlox (Phlox subulata) does well in zones 7 through 10. Prefers sunny, well-drained locations. |
| Vine | Carolina jessamine (Gelsemium sempervirens): A vigorous vine with yellow spring flowers. Grows in zones 7 to 9. |
| Perennial | Black-eyed Susan (Rudbeckia hirta) blooms throughout summer and does well in zones 3 to 9. |
| Shrub | Crepe myrtle (Lagerstroemia indica) provides colorful summer blooms and thrives in zones 7 to 10. |
| Tree | Southern magnolia (Magnolia grandiflora) is a broadleaf evergreen tree with fragrant blooms. Ideal for zones 7 to 10. |
Southeast (Zones 5 through 10)
| Category | Recommended Plant |
|---|---|
| Groundcover | Lilyturf (Liriope muscari) is drought-tolerant and evergreen. Thrives in both sun and shade. |
| Vine | Jasmine (Jasminum) is a fragrant vine with star-shaped blooms that does well across the Southeast. |
| Perennial | Sage (Salvia) such as 'Black and Blue' blooms year-round and grows beautifully in this region. |
| Shrub | Rosemary (Rosmarinus officinalis) is drought-tolerant, fragrant, and resists deer and rabbits. |
| Tree | Red maple (Acer rubrum) is native to the Southeast and known for its striking fall foliage. |
Southwest (Zones 3 through 10)
| Category | Recommended Plant |
|---|---|
| Groundcover | White clover (Trifolium repens) thrives in spring temperatures of 50°F–85°F. Great for erosion control. |
| Vine | Crossvine (Bignonia capreolata L.) prefers sunny, well-drained spots. Once established, it forms a strong root system. |
| Perennial | Poppies (Papaver) grow well in dry, sunny conditions and are drought-resistant once mature. |
| Shrub | Leadworts (Plumbago) are evergreen and thrive in zones 9 to 11 with full sun and light, well-drained soil. |
| Tree | Avocado trees (Persea americana) grow best in zones 9 to 11. Require 4–6 hours of sun and deep watering. |
Limitations of the USDA Map
While incredibly useful, the USDA hardiness zones don't account for:
Soil type
Rainfall patterns
Humidity levels
Summer heat (check AHS Heat Zones for that)
Elevation
Wind exposure
Sunlight hours
So always use your planting zone as a starting point, not a strict rule.
Understanding planting zones—from what they are to how they’re used—is one of the most important steps you can take as a gardener or grower. The USDA growing zone map offers a detailed guide to help you select the right plants for your climate, reduce gardening risks, and make the most of your growing space.
At EdenGreen, we believe smart gardening starts with knowing your zone. Whether you’re a beginner planting your first tomato or a seasoned horticulturist designing a four-season garden, understanding USDA zones, hardiness zones, and gardening zones empowers you to grow better.
Find your zone today using the USDA’s official map, and start building a garden that thrives year after year.
