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USDA Zones and Plant Lists

Our plant descriptions take "a" and "b" sub-zones into account. If you want to play it absolutely safe, buy plants that are hardy to your zone, not just marginally hardy to the "b" subzone.

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Zone 2
Zone 3
Zone 4
Zone 5
Zone 6
Zone 7
Zone 8
Zone 9
Zone 10

Note:
The USDA map doesn't account for some eastern climate factors, like the beneficial effect of a snow cover on perennials, freeze-thaw cycles or soil drainage. And in the West (west of the 100th meridian, which runs roughly through the middle of North and South Dakota and down through Texas west of Laredo), the map doesn't take altitude or precipitation into consideration. While cities in the same zone in the East can have similar climates and grow similar plants, it varies greatly in the West. For example, rainy, low-elevation Seattle and arid, high-elevation Tucson, Ariz., are both in USDA Zone 8. Check with your local extension office or local nurseries for more detailed growing information.

A myriad of factors — together called the microclimate — affect a plant's ability to withstand winter in a certain location, including exposure (or lack of it) to sun, proximity to a building, protection from winter winds, amount of soil moisture, etc. In that way, many plants can often be "pushed" into overwintering in an area that's technically too cold for them.

Average minimum temperature: -40 to -50 F
Average last frost date: May 1 - 31
Average first frost date: August 1 - 31

USDA Zone 2 includes a large part of Alaska and Canada. In the southern part of the zone, natural areas are mostly forested; farther north, the land becomes swampy and, in the northernmost regions, permafrost is present in the subsoil. Annual precipitation ranges from 20 to 40 inches. Paper birch (Betula papyrifera), quaking aspen (Populus tremuloides), bunchberry dogwood (Cornus canadensis), European white birch (Betula pendula), Pennsylvania cinquefoil (Potentilla pensylvanica), Lapland rhododendron (Rhododendron lapponicum), netleaf willow (Salix reticulata), Amur chokecherry (Prunus maackii), Eastern larch (Larix laricina) and bush cinquefoil (Potentilla fruticosa) are hardy here. A wide range of conifers do well, including a number of firs, spruces, plus Scotch and mugo pines. Herbaceous plants include bleeding heart, monkshood, summer phlox (Phlox paniculata), columbine and Himalayan poppy.

The USDA hardiness zone map is based on average minimum winter temperatures, each zone representing a 10-degree difference from the ones above and below it. Each zone is further divided into "a" and "b" areas. The difference between
each of these subzones is a matter of five degrees. The average minimum temperature in winter in Zone 2a is -45 to -50F. In Zone 2b, it's -40 to -45F.

Sample Cities in USDA Zone 2a

Prudhoe Bay, Alaska
Flin Flon, Manitoba

Sample Cities in USDA Zone 2b

Unalakleet, Alaska
Pinecreek, Minnesota

Plants for USDA Zone 2

Trees and Shrubs
Conifers
Perennials

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USDA Zone 3

Average minimum temperature: -30 F to -40 F
Spring: April 15 - June 15
Average last frost date: May 1- 31
Average first frost date: September 1 - 30
Fall: August 15 - October 1

For the most part, USDA Zone 3 stretches along the U.S.-Canadian boundary. Winter temperatures plummet to -40 to -30 F, while summers are warm to hot. Away from the coast, the zone is subject to relatively dry conditions — in International Falls, average precipitation is slightly less than 23 inches, and in Sidney, Montana, 14 inches; closer to the coast, precipitation rises — Van Buren, Maine, 37.5 inches. Depending on the area, the growing season can be as short as two months or as long as four.

Although dormancy is long and plant roots freeze, the plants that are adaptable to the climate seem to come out of winters relatively unscathed. Redosier dogwood (Cornus sericea), American arborvitae (Thuja occidentalis), paper birch (Betula papyrifera), bunchberry dogwood (Cornus canadensis), Eastern larch (Larix laricina), bush cinquefoil (Potentilla fruticosa) and American cranberry bush (Viburnum trilobum) do well here. Hosta, daylily, bluestar, alyssum, blanket flower (Gaillardia), penstemon, garden phlox, creeping Jenny and coneflower are some of the many perennials that are hardy in this zone. Needled evergreens do well here, but the only broadleaf evergreens that make it in this climate are prostrate forms that are low enough to be covered by snow. Where summers are warm, cereal crops do very well, as do root crops and spinach.

The USDA hardiness zone map is based on average minimum winter temperatures, each zone representing a 10-degree difference from the ones above and below it. Each zone is further divided into "a" and "b" areas. The difference between each of these sub-zones is a matter of five degrees. The average minimum temperature in winter in Zone 3a is -35 to -40F. In Zone 3b, it's -30 to -35 F.

Sample Cities in USDA Zone 3a

International Falls, Minnesota
St. Michael, Alaska

Sample Cities in USDA Zone 3b

Tomahawk, Wisconsin
Sidney, Montana
Crosby, North Dakota

Plants for USDA Zone 3

Deciduous Shrubs
Deciduous Trees
Conifers
Perennials
Vines

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USDA Zone 4

Average minimum temperature: -20 F to -30 F
Spring: April 15 - June 15
Average last frost date: May 1 - 30
Average first frost date: September 1 - 30
Fall: September 1 - October 15

USDA Zone 4 encompasses a wide area along the northern U.S. and around the Great Lakes. Plants have to endure long periods of deep cold and sometimes surprisingly hot dry summers. In many places, ancient glaciers created deep, rich, dark soil. On average, the growing season is five to six months long. Depending on the area, rainfall can measure as low as 10 inches or as high as 40.

A usually constant snow cover in the colder areas helps protect plants, and there's a wide variety of perennials and other herbaceous plants that do well here — peony, coneflower (Echinacea), liatris, some bell flowers (Campanula), lamb's ear, foamflower (Tiarella), sedum and sunflower (Helianthus), to name a few. Although fewer woody ornamentals grow here (as compared to warmer zones), sugar maple (Acer saccharum), spruce (Picea), fir (Abies), panicle hydrangea (Hydrangea paniculata), lilac, Chinese juniper (Juniperus chinensis), viburnums and Vanhoutte spirea (Spiraea x vanhouttei) are among the hardy. Wheat, oats, cherries, apples, potatoes and beets are some of the common food crops.

The USDA hardiness zone map is based on average minimum winter temperatures, each zone representing a 10-degree difference from the ones above and below it. Each zone is further divided into "a" and "b" areas. The difference between each of these sub-zones is a matter of five degrees. The average minimum temperature in winter in Zone 4a is -25 to -30 F. In Zone 4b, it's -20 to -25 F.

Sample Cities in USDA Zone 4a

Minneapolis-St.Paul, Minnesota
Lewistown, Montana

Sample Cities in USDA Zone 4b

Northwood, Iowa
Scottsbluff, Nebraska
Worthington, Minnesota

Plants for USDA Zone 4

Deciduous Shrubs
Deciduous Trees
Broadleaf Evergreens
Conifers
Perennials
Vines

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USDA Zone 5

Average minimum temperature: -10 F to -20 F
Spring: April 15 - June 15
Average last frost date: March 30 - April 30
Average first date: September 30 - October 30
Fall: September 1 - October 15

Plants have to stand up to sweeping winds, prolonged cold and, in the West, low-humidity winters. The western part of the zone in the U.S. has relatively little precipitation, averaging 12 to 20 inches a year; snow cover is often scarce. Soils are usually alkaline. In the eastern part of the zone, the amount of moisture increases, supporting a wider variety of plant material. There, soils range from neutral to slightly acidic.

Witch hazel (Hamamelis virginiana), oakleaf hydrangea (Hydrangea quercifolia), Kousa dogwood (Cornus kousa), rose of Sharon (Hibiscus syriacus), hawthorn (Crataegus), European beech (Fagus sylvatica), American holly (Ilex opaca) and apples (Malus) all are hardy here. Broadleaf evergreens like rhododendron, mountain laurel, and Pieris need shelter and protection if they're going to make it in this zone. This is the coldest area that selected cultivars of Japanese maple (Acer palmatum) can take. Perennials such as black-eyed Susans (Rudbeckia) and coreopsis can tough it out in the sometimes harsh conditions of the western plains. Where more moisture is available, astilbe, hostas and lobelias do well.

The USDA hardiness zone map is based on average minimum winter temperatures, each zone representing a 10-degree difference from the ones above and below it. Each zone is further divided into "a" and "b" areas. The difference between each of these sub-zones is a matter of five degrees. The average minimum temperature in winter in Zone 5a is -15 to -20 F. In Zone 5b, it's -10 to -15 F.

Sample Cities in USDA Zone 5a

Des Moines, Iowa
Boulder, Colorado
Kalispell, Montana

Sample Cities in USDA Zone 5b

Effingham, Illinois
Columbia, Missouri
Mansfield, Pennsylvania
Lamar, Colorado

Plants for USDA Zone 5

Deciduous Shrubs
Deciduous Trees
Broadleaf Evergreens
Conifers
Perennials
Vines

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USDA Zone 6

Average minimum temperature: 0 F to -10 F
Spring: March 15 - May 15
Average last frost date: March 30 - April 30
Average first frost date: September 30 - October 30
Fall: September 15 - November 15

From high, dry desert to low-lying, wet coastal areas, from low mountains in Virginia and West Virginia to open prairies in the Midwest, Zone 6 comprises a wide range of climatic conditions, topographies and rainfall. Gardeners enjoy a great diversity of shrubs and trees: Zone 6 represents the warmest climate that some cold-loving plants can tolerate, and it's often the coldest area that mild-climate plants can over-winter in.

The plants that do the best in the Midwest region are those like coneflowers (Echinacea) that can handle winter's cold and stand up to summer heat. Zone 6 is the coldest area that bigleaf hydrangea (Hydrangea macrophylla), common boxwood (Buxus sempervirens), Japanese apricot (Prunus mume), Atlas cedar (Cedrus atlantica), English holly (Ilex aquifolium) and some cherry laurels Prunus laurocerasus) cultivars can handle. Hardy perennials include Alstroemeria, red-hot poker (Kniphofia), hardy begonia and some sedges.

The USDA hardiness zone map is based on average minimum winter temperatures, each zone representing a 10-degree difference from the ones above and below it. Each zone is further divided into "a" and "b" areas. The difference between each of these sub-zones is a matter of five degrees. The average minimum temperature in winter in Zone 6a is -5 to -10 F. In Zone 6b, it's 0 to -5 F.

Sample Cities in USDA Zone 6a

Carbondale, Illinois
St. Louis, Missouri
Lebanon, Pennsylvania

Sample Cities in USDA Zone 6b

McMinnville, Tennessee
Branson, Missouri
Tulsa, Oklahoma

Plants for USDA Zone 6

Deciduous Shrubs
Deciduous Trees
Broadleaf Evergreens
Conifers
Perennials
Vines

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USDA Zone 7

Average minimum temperature: 0 F to 10 F
Spring: February 15 - April 15
Average last frost date: March 30 - April 30
Average first frost date: September 30 - October 30
Fall: September 15 - November 15

In the East, Zone 7 extends from Virginia and much of the interior of North Carolina through the upper half of Georgia, Alabama, Mississippi and Louisiana. In the mid section of the country, it cuts a wide path through Arkansas and north-central Texas. From Arizona, it extends as a thin line through the mountains of California up through the interior of the Pacific Northwest. Except in the Southwest, most areas of this zone receive moderate to high rainfall. There's usually not much snow cover in the winter, so mulch is useful in protecting marginal plants.

This is the northernmost zone for needle palm (Rhapidiophyllum hystrix), fragrant teaolive (Osmanthus fragrans), laurustinus (Viburnum tinus), Chinese fringe-flower (Loropetalum chinense), passionflower, cupflower (Nierembergia), and most cannas. In the Southeast, crape myrtle (Lagerstroemia indica) can reach its full stature as a tree rather than occasionally losing top growth as it sometimes does in Zone 6.

The USDA hardiness zone map is based on average minimum winter temperatures, each zone representing a 10-degree difference from the ones above and below it. Each zone is further divided into "a" and "b" areas. The difference between each of these sub-zones is a matter of five degrees. The average minimum temperature in winter in Zone 7a is 0 to 5 F. In Zone 7b, it's 5 to 10F.

Sample Cities in USDA Zone 7a

Oklahoma City, Oklahoma
South Boston, Virginia
Lubbock, Texas

Sample Cities in USDA Zone 7b

Little Rock, Arkansas
Griffin, Georgia
Fort Stockton, Texas

Plants for USDA Zone 7

Deciduous Shrubs
Deciduous Trees
Broadleaf Evergreens
Conifers
Perennials
Vines

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USDA Zone 8

Average minimum temperature: 10 F to 20 F
Spring: January 15 - March 1
Average last frost date: February 28 - March 30
Average first frost date: October 30 - November 30
Fall: October 1 - December 1

USDA Zone 8 forms a wide ribbon across the lower half of southern states, tapering to a narrow band that encompasses the Sierra foothills in California and the Pacific Northwest coast. A temperate climate with relatively mild winters and a long growing season, Zone 8 is home to some of the world's most beautiful gardens. Unlike the British Isles, which is also in the same zone, the chief limiting factor in some parts of Zone 8 in the U.S. is the degree of summer heat. In the Southeast, summers are hot and humid; in hot, dry areas of Texas and the Southwest, plants undergo dormancy in summer. In the Pacific Northwest, summer means warm days and cool nights.

The zone represents the southernmost limit for astilbe, Kousa dogwood and smoke tree (Cotinus coggygria). This is the coldest zone for strawberry tree (Arbutus unedo), Himalayan pieris (Pieris formosana var. forrestii) and rock rose (Cistus). Dahlias and gladiolus can be left in the ground to overwinter.

The USDA hardiness zone map is based on average minimum winter temperatures, each zone representing a 10-degree difference from the ones above and below it. Each zone is further divided into "a" and "b" areas. The difference between each of these sub-zones is a matter of five degrees. The average minimum temperature in winter in Zone 8a is 10 to 15F. In Zone 8b, it's 15 to 20F.

Sample Cities in USDA Zone 8a

Shreveport, Louisiana
Tifton, Georgia
Dallas, Texas

Sample Cities in USDA Zone 8b

Austin, Texas
Gainesville, Florida
Apalachicola, Florida

Plants for USDA Zone 8

Deciduous Shrubs
Deciduous Trees
Broadleaf Evergreens
Conifers
Perennials
Vines

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USDA Zone 9

Average minimum temperature: 20 F to 30 F
Spring: January 1 - March 1
Average last frost date: Jan 30 - February 28
Average first frost date: November 30 - December 30
Fall: October 1 - December 1

In the Florida peninsula and the southern edges of Louisiana, summers are hot and humid. In Texas west to California, summers are hot and dry. Here, the climate is often referred to as Mediterranean; many of the plants that do well in the Southwest — rosemary, thyme, lavender — also thrive in southern Europe, Greece and Turkey.

Many of the plants found here have developed a way to handle heat and drought-leaves are fleshy and hold moisture, spines deter animal grazing. Often they undergo a summer dormancy. Others such as clematis, daylilies and coreopsis are at their heat limit; they succumb in warmer zones. Asparagus fern (Asparagus setaceus), fuchsia hybrids, Tasmanian blue gum (Eucalyptus globulus), caladium and the California pepper tree (Schinus molle) are hardy here. But gardeners should be more concerned about tolerance to summer heat and drought as cold-hardiness. In the Southwest, choose plants like desert ruellia (Ruellia sp.), santolina, spotted emu bush (Eremophila maculata), agave and trident sage (Salvia x trident). Citrus, olives, figs, stone fruits, avocados and grapes are large agricultural crops.

The USDA hardiness zone map is based on average minimum winter temperatures, each zone representing a 10-degree difference from the ones above and below it. Each zone is further divided into "a" and "b" areas. The difference between each of these sub-zones is a matter of five degrees. The average minimum temperature in winter in Zone 9a is 20 to 25 F. In Zone 9b, it's 25 to 30 F.

Sample Cities in USDA Zone 9a

Houston, Texas
St. Augustine, Florida
New Orleans, Louisiana

Sample Cities in USDA Zone 9b

Brownsville, Texas
Fort Pierce, Florida
Yuma, Arizona

Plants for USDA Zone 9

Deciduous Shrubs
Deciduous Trees
Broadleaf Evergreens
Conifers
Perennials
Vines

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USDA Zone 10

Average minimum temperature: 30 F to 40 F
Spring: January 1 - March 1
Average last frost date: January 30 or before
Average first frost date: November 30 - December 30
Fall: October 1 - December 1

Zone 10 includes southern Florida and southern California. Steamy and wet summers are the rule in southern Florida. Cool wet winters and hot dry summers are typical in most of southern California, except for coastal areas where summer temperatures are more moderate. Along the coast, frosts are rare and brief. In southern California, a wide and complicated
variety of conditions-- influenced by elevation, humidity, proximity to the coast and rainfall-means that an extremely wide variety of plants are at home here. Bougainvillea (Bougainvillea spectabilis), lemon eucalyptus Eucalyptus citriodora), rubber plant (Ficus elastica), royal palm (Roystonea regia) and golden shower (Cassia fistula) are hardy here.

The USDA hardiness zone map is based on average minimum winter temperatures, each zone representing a 10-degree difference from the ones above and below it. Each zone is further divided into "a" and "b" areas. The difference between each of these sub-zones is a matter of five degrees. The average minimum temperature in winter in Zone 10a is 30 to 35 F. In Zone 10b, it's 35 to 40 F.

Sample Cities in USDA Zone 10a

Naples, Florida
Marco Island, Florida
Victorville, California

Sample Cities in USDA Zone 10b

Miami, Florida
Coral Gables, Florida
Homestead, Florida

Plants for USDA Zone 10

Trees and Shrubs
Herbaceous Plants
Vines

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