USDA Plant Hardiness Zones: Find Your Zone & What to Plant

What Is a USDA Hardiness Zone?

A USDA Plant Hardiness Zone is the single most important number a gardener can know. Published by the U.S. Department of Agriculture's Agricultural Research Service, the zone map divides the country into 13 zones based on one thing: the average annual extreme minimum winter temperature — the coldest night your area typically sees each year.

That number matters because it determines which perennial plants, trees, and shrubs will survive your winter. A plant rated “hardy to Zone 6” can handle winter lows down to -10°F. Plant it in Zone 5 (where lows hit -20°F), and you're gambling. Plant it in Zone 7, and it will coast through winter without complaint.

Each zone spans a 10°F range and is further divided into two sub-zones: “a” (the colder half) and “b” (the warmer half), each covering 5°F. Zone 6a (-10 to -5°F) is meaningfully different from Zone 6b (-5 to 0°F) when you're choosing a marginally hardy fig tree or a borderline-tough crepe myrtle.

The map was first published in 1960 and has been updated periodically as climate data accumulates. The most recent version, released in November 2023, uses 30 years of weather data (1991-2020) and shifted roughly half the country into a warmer half-zone compared to the 2012 edition.

Zones tell you what will survive your winter. They don't tell you what will thrivein your summer, how much rain you'll get, or what your soil is like. A plant that's hardy in your zone can still fail if it needs full sun and you plant it in shade, or if it demands acidic soil and yours is alkaline.

That said, zones are the essential starting filter. Below, we link to dedicated guides for each zone — with specific plant recommendations, growing tips, and frost dates for zones 3 through 10.

Sub-zones: When the Half-Zone Actually Matters

The USDA divides each zone into two halves: “a” (the colder 5°F) and “b” (the warmer 5°F). Zone 6 splits into Zone 6a (-10 to -5°F) and Zone 6b (-5 to 0°F). Most casual gardeners ignore this distinction. Sometimes that's fine. Sometimes it costs them a $300 tree.

Here's when sub-zones actually matter:

Marginally hardy plants. A plant rated “hardy to Zone 7” usually means Zone 7b. Plant it in Zone 7a, and you'll lose it in a hard winter. Crepe myrtles, gardenias, hardy figs, and Mediterranean herbs like rosemary all sit on these edges.
Fruit trees and shrubs. Peach, fig, and citrus varieties are bred for specific zones. A “Hardy 6-9” peach might mean 6b-9, not 6a-9. The catalog details matter more than the headline range.
First-winter perennials. Cold-edge losses happen most often in the first winter, before roots are fully established. If your plant is rated for your exact zone with no buffer, give it winter protection year one.

And when you can ignore sub-zones entirely:

Plants rated for zones colder than yours. A Zone 4-hardy hosta will sail through Zone 6a or 6b without issue.
Annuals. They're not surviving winter regardless.
Plants you bring inside in winter. Same logic.

The rule of thumb: if a plant is rated for your zone exactly with no buffer in either direction, pay attention to whether you're in the “a” or “b” half. If there's a full zone of safety either way, you're fine.

How to Read a Plant Tag

Walk into any nursery and you'll see plant tags with cryptic codes: “USDA 5-9”, “Hardy to -10°F”, “Zone 6”, “Zones 4-7”. They mean roughly the same thing — but the differences matter when you're standing at the garden center deciding whether to take something home.

“Zones 5-9” — The plant survives in zones 5 through 9. Below Zone 5, winters are too cold. Above Zone 9, summers may be too hot, or the plant isn't getting enough winter chill (more on that in the heat zones section below).
“Hardy to Zone 5” — Cold tolerance only. The plant might also struggle in hot zones, but the tag isn't telling you. Check the description for heat tolerance.
“Hardy to -20°F” — Equivalent to Zone 5 (Zone 5 is -20 to -10°F). Some growers prefer temperature directly because it's more precise than the zone number.
“USDA 6” vs “USDA 6a” vs “USDA 6b” — The more specific the rating, the more confidence the grower has. If a tag specifies “6b”, the breeder is telling you this plant won't reliably survive Zone 6a winters.

Things tags often hide: whether the rating assumes winter protection (mulching, wrapping); whether the plant will survive but not thrive at the edges of the rated range; heat tolerance (almost never on tags); and soil requirements that may make the plant fail even in the “right” zone.

The honest truth: zone ratings on tags are conservative. Most plants survive a half-zone colder than rated if conditions are otherwise good. But “most” isn't “all,” so don't bet a $300 specimen tree on it without backup plans.

Zone-by-Zone Overview

Below is a closer look at each USDA zone from 3 through 10. For each one you'll find an overview of the climate, what kinds of plants thrive, the main challenges, and a link to the dedicated zone page with the full plant list and growing tips.

Zone 3-40 to -30°F · May 15 - Sep 15 (120 days)

Very cold winters, short growing season

Zone 3 covers the coldest parts of the continental US — northern Minnesota, northern Maine, interior Alaska, and high-elevation mountain regions. With winter lows reaching -40°F and a frost-free window of just 120 days, this is gardening on the edge. But it's not impossible: the summer is short and intensely sunny, and a surprising range of plants thrive when chosen carefully.

Cold-hardy perennials like peonies, hostas, daylilies, and bleeding hearts handle the winters fine. Hardy vegetables — peas, beets, garlic, brassicas, lettuce — produce well in the brief growing window. Even fruit works here: hardy apples and rhubarb are reliable, blueberries excel with proper soil prep, and raspberries are productive once established.

The constant threat is frost. You can lose plants in any month from September through June, and season-extension tools (cold frames, low tunnels, raised beds) aren't optional — they're standard equipment. Start everything you can indoors, mulch heavily for winter, and choose the most cold-hardy variety of every plant. When the average winter is brutal, the once-in-a-decade winter is catastrophic.

See all 45 plants for Zone 3→

Zone 4-30 to -20°F · May 10 - Sep 30 (140 days)

Cold winters, moderate growing season

Zone 4 covers the northern plains, much of upstate New England, northern Wisconsin and Michigan, and parts of the Mountain West. Winters are cold but the growing season — about 140 frost-free days — is workable for most traditional gardening. This is where many of the classic gardening books were written; the standard advice mostly applies here.

Most cold-hardy perennials work without special protection: hostas, peonies, daylilies, irises, and sedum. Vegetables follow the standard playbook — tomatoes, peppers, beans, squash, root crops, brassicas — though you'll want to start tomatoes and peppers indoors to get a jump on the season. Hardy fruit trees (apples, pears, plums, sour cherries) do well, and small fruits like blueberries, raspberries, and currants thrive.

The challenges are predictable: late spring frosts can take out tender transplants, and early fall frosts shorten the harvest window. Watch your local frost dates carefully — they vary by 2-3 weeks across short distances based on elevation and proximity to water. For marginal plants, choose varieties rated for Zone 3 as a buffer; one polar vortex can wipe out a Zone 4-rated perennial that's been thriving for years.

See all 57 plants for Zone 4→

Zone 5-20 to -10°F · Apr 30 - Oct 15 (170 days)

Cold winters, good growing season

Zone 5 is one of the most versatile growing zones in North America. It covers the lower Great Lakes region, much of central New England, the central plains, and parts of the Pacific Northwest interior. With 170 frost-free days and reliable winter chill, it's a sweet spot for both food and ornamental gardening — wide enough to grow most temperate plants, cold enough to provide the dormancy that fruit trees and many perennials need.

Almost any vegetable in a typical seed catalog produces well in Zone 5. Tomatoes, peppers, eggplant, and melons have enough season to ripen if you start them indoors. Asparagus thrives here — this is the sweet spot for asparagus production. Blueberries excel with acidic soil prep. Most fruit trees (apples, pears, sour cherries, plums) are reliable, and even peaches can work in protected microclimates.

The main challenges are polar vortex events that can briefly drop temperatures below the zone average, and occasional summer heat waves. For high-value plants, choose varieties rated to at least Zone 4 as insurance. Beyond that, Zone 5 rewards almost any reasonable gardening effort — if you can't grow it here, the problem is probably soil or sun, not zone.

See all 72 plants for Zone 5→

Zone 6-10 to 0°F · Apr 15 - Oct 30 (200 days)

Moderate winters, long growing season

Zone 6 is the gardening sweet spot for much of the United States. Covering the mid-Atlantic, central plains, much of the Ohio Valley, and parts of the Pacific Northwest, it offers an excellent balance of winter chill and warm summers. With 200 frost-free days and moderate winter lows, this zone supports almost everything sold at the average garden center — and most plants don't even need special protection.

Tomatoes and peppers thrive. Vegetables in general are forgiving. Hydrangeas, peonies, roses, lilacs, and dogwoods all perform reliably. Fruit trees — apples, pears, peaches, sour cherries — produce well, though sweet cherries can be tricky. Many marginally hardy plants survive here with minimal protection: figs, crepe myrtles, and certain camellias are realistic in Zone 6b with the right siting.

If you're in Zone 6, the challenge shifts from “will it survive?” to “what do I want to grow?” The variety available is enormous, and most standard gardening advice applies without modification. The main mistakes here are overconfidence (planting marginal Zone 7 plants in unprotected sites) and underestimating summer heat in late July and August, when even normally hardy plants benefit from afternoon shade.

See all 75 plants for Zone 6→

Zone 70 to 10°F · Apr 1 - Nov 15 (230 days)

Mild winters, long warm season

Zone 7 covers a wide swath of the country: the mid-Atlantic coast, central Tennessee and Kentucky, much of California's interior valleys, and parts of the Pacific Northwest. With mild winters and a long growing season — about 230 frost-free days — you can grow more variety here than almost anywhere. The challenge shifts from “will it survive winter?” to “will it tolerate summer?”

Cool-season crops can be grown twice (spring and fall). Warm-season vegetables have a long window. Figs become reliable — most varieties survive Zone 7 winters with no protection. Crepe myrtles are essentially unkillable here. Lavender thrives in well-drained spots. Camellias and gardenias work in protected areas. Magnolias bloom heavily.

The main pitfall is summer heat. Cool-loving plants like rhododendrons, hostas, and many traditional vegetables (peas, lettuce, brassicas) need afternoon shade or they'll struggle in late July and August. Heat-tolerant varieties matter more than zone-appropriate ones. The other consideration is water — Zone 7 areas range from humid (mid-Atlantic) to arid (interior California), and “Zone 7” alone doesn't tell you which kind.

See all 79 plants for Zone 7→

Zone 810 to 20°F · Mar 15 - Nov 30 (260 days)

Warm, occasional light frost

Zone 8 is the entry point to Sun Belt gardening. It covers much of the southern US — the Southeast coastal plains, much of Texas, the lower Pacific Northwest coast, and the warm interior valleys of California. Winters are mild with only occasional light frosts, and the growing season runs nearly nine months. This is where Mediterranean and subtropical plants become realistic outdoor candidates.

Olives can grow in the ground here. Fig varieties produce abundantly. Citrus is possible in sheltered spots, especially in 8b. Hibiscus, lavender, rosemary, and bay laurel thrive. Vegetables have a long season but need scheduling adjustments: many cool-season crops (peas, lettuce, broccoli) need to grow in the cooler shoulder seasons rather than summer, when the heat will bolt them immediately.

The biggest mistake Zone 8 gardeners make is treating it like a cooler zone. Summer heat is the limiting factor for most plants. Northern transplants struggle here — peonies, lilacs, and rhododendrons don't get enough winter chill or burn in summer. Choose varieties bred for hot climates. “Low-chill” peach and apple varieties exist specifically for Zone 8. Afternoon shade isn't optional for most non-native plants.

See all 76 plants for Zone 8→

Zone 920 to 30°F · Feb 15 - Dec 15 (300 days)

Hot summers, mild winters

Zone 9 covers much of Florida, southern Texas, southern Arizona, the Central Valley of California, and the southern California coast. With long, hot summers and very mild winters, you're essentially gardening in a different paradigm than Zone 6 or 7. Heat tolerance — not cold hardiness — is the primary concern when choosing plants.

Citrus thrives here outdoors. Avocados are commercially viable in 9b and warmer. Bougainvillea, hibiscus, and bird of paradise become landscape staples. Vegetable gardens can run nearly year-round, but the schedule inverts: tomatoes get planted in winter, harvested in spring, and finish before the brutal summer. Many traditional summer crops actually fail here because they can't take the heat.

The big challenge is that Zone 9 is too warm for many plants that need winter chill. Apples, sour cherries, peonies, lilacs, and many traditional perennials simply won't bloom or fruit here — they need a certain number of “chill hours” below 45°F that Zone 9 doesn't provide. The flip side: an enormous range of subtropical plants becomes available. Look for “low-chill” varieties of any temperate plant you want to grow, and accept that Zone 9 is its own gardening world.

See all 53 plants for Zone 9→

Zone 1030 to 40°F · Year-round (365 days)

Tropical/subtropical, frost-free

Zone 10 is essentially frost-free — temperatures rarely dip below freezing for more than a few hours, and most years see no frost at all. This zone covers South Florida, the southernmost tip of Texas, parts of southern California's coast, and the warmest pockets of the southwest. Year-round gardening is the default, but most temperate gardening rules don't apply.

Tropical plants thrive here outdoors: mango, banana, papaya, guava, citrus of all kinds, plumeria, bird of paradise, bougainvillea. Many “houseplants” you see in northern garden centers are actually landscape plants here. Vegetables can be grown nearly year-round, but the seasons are flipped — winter is the prime growing season for leafy greens and cool-season crops, while summer becomes the rest period for heat-loving plants only.

The biggest challenge is the lack of winter chill. Apples, pears, peonies, lilacs, peaches (most varieties), and cherries simply cannot fruit or bloom properly without sustained cold. The other challenge is intense summer heat and humidity, which favors disease and pest pressure. Choose tropical-adapted varieties, schedule plantings around the heat, and accept that you're doing a fundamentally different kind of gardening than Zone 6 readers will recognize.

See all 37 plants for Zone 10→

Beyond Zones: Microclimates in Your Yard

Your USDA zone is a regional average, but your yard isn't average. Every property has microclimates— small pockets that behave differently from the zone number on the map. Understanding them lets you push boundaries and grow plants that technically shouldn't work in your zone.

South-facing walls absorb heat during the day and radiate it at night, creating a pocket that can be a full zone warmer than the rest of your yard. A Zone 6 gardener with a south-facing brick wall might successfully grow a Zone 7 fig tree right against it. North-facing exposures, by contrast, stay cooler and shadier.

Urban heat islands make cities measurably warmer than surrounding suburbs and rural areas — often by 2-5°F on winter nights. If you garden in a dense urban area, your effective zone may be half a step warmer than the map shows.

Cold air drainage is the reverse problem. Cold air is denser than warm air, so it flows downhill and pools in low spots like valley floors and the base of slopes. A hilltop garden and a valley-bottom garden in the same zip code can be in different effective zones. If you notice frost lingering in the low spots of your yard while the slope stays clear, that's cold air drainage at work.

Elevation matters too. Temperature drops about 3.5°F for every 1,000 feet of elevation gain. A mountain property at 5,000 feet will be roughly one full zone colder than a nearby town at 3,000 feet, even if they share the same zip code.

The takeaway: use your zone as a starting point, but analyze your specific yard to understand where the warm pockets, cold traps, and microclimates actually fall. That's what separates gardeners who successfully push zone boundaries from those who lose plants every winter.

AHS Heat Zones: The Other Half of Hardiness

Here's a question that exposes the biggest gap in how most people think about plant hardiness: why does the same plant thrive in zones 5-9 in some places but die in others within that range?

The answer is heat. The American Horticultural Society publishes the AHS Plant Heat Zone Map, a counterpart to the USDA cold map. Where USDA zones measure annual winter cold, heat zones measure the average number of days per year above 86°F — the temperature at which heat stress starts damaging plant cells.

Heat zones run from 1 to 12. Zone 1 has fewer than 1 day above 86°F per year (think: Alaska). Zone 12 has more than 210 days (think: Florida, southern Texas, Phoenix). Most gardeners have never heard of these zones, but they explain failures that don't make sense by USDA cold zones alone.

Why this matters: A plant rated “USDA 5-9” might actually need AHS heat zones 1-7. Plant it in Houston (USDA 9, AHS 9) and the cold rating is technically right, but the heat will cook it. This is why northern transplants — rhododendrons, lilacs, peonies — struggle in hot southern zones even when the cold rating “matches.”

The reverse problem also happens: a plant from a hot climate (bougainvillea, some hibiscus, certain citrus) might survive cold zones if sheltered, but it will perform poorly because it's not getting the heat it expects to flower and fruit properly.

The catch: AHS heat zones are barely on plant tags. Most garden centers don't carry the dual rating. The American Horticultural Society publishes the map, and a small number of breeders use both ratings (e.g., “USDA 5-9, AHS 9-2”), but it's rare. Until that changes, you have to do the heat-zone math yourself.

Practical takeaway: If you live in a hot zone (USDA 8 or warmer) and a plant is failing despite being “in your zone,” it's probably a heat problem, not a cold problem. Look for varieties bred specifically for hot climates, or check the AHS map directly. For most cold-zone gardeners (3-7), heat isn't usually the limiting factor — but as climate shifts, more of us will need to think about it.

Zone Shifts & Climate Change

When the USDA released its updated zone map in November 2023, roughly half the country had shifted into a warmer half-zone compared to the previous 2012 map. This wasn't a surprise — winter minimum temperatures have been trending warmer for decades — but it officially changed the zone designation for millions of gardeners.

What does this mean practically? If you were Zone 6b and are now Zone 7a, you can probably grow plants that were previously risky for you. Crepe myrtles, gardenias, and certain fig varieties that needed winter protection may now sail through unscathed. But proceed cautiously: zone averages smooth out the occasional brutal winter, and one polar vortex can still kill a plant that's only marginally hardy in your new zone.

The practical advice: plant for the zone you're in now, but choose cultivars that tolerate one zone colder as insurance. If you're Zone 7a, pick plants rated hardy to at least Zone 6. That way, a once-in-a-decade cold snap won't wipe out your investment.

Common Mistakes When Using Zones

Knowing your zone is the easy part. Using it correctly is where most gardeners trip up. After years of helping people plant trees and shrubs that should outlive their mortgages, here are the mistakes I see most often.

1. Treating zones as guarantees, not ranges. A plant rated “Zone 6” doesn't survive every Zone 6 winter — it survives an average Zone 6 winter. One polar vortex can wipe out a plant that's been thriving for years. For high-value purchases, choose plants rated at least one zone colder than yours as a buffer.

2. Buying plants from a different climate. Nursery stock grown in California or Florida and shipped to Minnesota is hardened to mild winters. Even if the variety is rated for Zone 4, the individual plant hasn't been through a real winter yet. First-winter losses are common with mail-order stock from distant nurseries. Buy local when you can.

3. Forgetting that “cold hardy” isn't “cold tolerant when planted in November.” A plant rated for your zone needs time to establish before winter. Plant most perennials and shrubs at least 6 weeks before your average first frost so the roots can grow in. Late-fall plantings of marginal plants often die not because the variety is wrong but because the timing is.

4. Trusting the zone above all else. Cold hardiness is one variable. Sun exposure, soil drainage, summer heat, water, and wind all matter. A plant rated for your zone will still die if you put it in soggy clay when it needs sandy loam — the zone label can't override basic site requirements.

5. Not protecting marginal plants. If you're growing a Zone 7 plant in Zone 6, don't just trust the label — mulch heavily, wrap the trunk, or plant against a south-facing wall. These small interventions are the difference between losing the plant and having it thrive.

6. Ignoring sub-zones on borderline plants. Already covered above, but worth repeating. The difference between Zone 7a and 7b is the difference between losing a crepe myrtle and watching it bloom for thirty years.

7. Assuming the 2023 update means you can ignore the old rules. Yes, many zones shifted warmer. But one warm decade doesn't erase the possibility of a cold one. Plant for resilience, not optimism.

Frequently Asked Questions

What is a USDA hardiness zone?

A USDA Plant Hardiness Zone is a geographic area defined by its average annual extreme minimum winter temperature. The USDA divides the United States into 13 zones (1 through 13), each representing a 10°F range. Zone 1 is the coldest (-60°F) and Zone 13 is the warmest (60-70°F). Gardeners use zones to determine which perennial plants will survive winter in their area.

How do I find my USDA hardiness zone?

Enter your zip code in the zone finder above and we'll tell you instantly. You can also check the official USDA Plant Hardiness Zone Map at planthardiness.ars.usda.gov. Your zone is based on the average coldest temperature your area experiences each winter, calculated from weather data over a 30-year period.

What is the difference between zone 6a and 6b?

Each USDA zone is divided into two sub-zones: 'a' (the colder half) and 'b' (the warmer half), each spanning a 5°F range. For example, Zone 6a has average minimums of -10 to -5°F, while Zone 6b ranges from -5 to 0°F. This distinction matters most for marginally hardy plants that sit right on the edge of survival in your zone.

Do USDA zones change over time?

Yes. The USDA updates the map every 10-15 years based on new climate data. The most recent update in November 2023 shifted roughly half of the country into a warmer half-zone compared to the 2012 map, reflecting rising winter minimum temperatures. If you haven't checked your zone recently, it may have changed.

Does my zone tell me when to plant?

Not directly. Your zone tells you what will survive winter, not when to plant. Planting timing depends on your frost dates — the last spring frost and first fall frost. However, zones correlate strongly with frost dates: Zone 3 is typically frost-free from May to September, while Zone 9 is frost-free from February to December. Check our individual plant guides for zone-specific planting calendars.

What if a plant is rated for a different zone than mine?

If a plant is rated for a warmer zone, you may still grow it with protection: mulching, cold frames, south-facing microclimates, or growing it as an annual. If it's rated for a cooler zone, the plant may struggle with summer heat rather than winter cold — afternoon shade and extra watering can help. Our plant guides include zone-specific tips for pushing boundaries.

What is an AHS heat zone, and how is it different from a USDA zone?

USDA hardiness zones measure the average annual minimum winter temperature — in other words, how cold your winters get. AHS heat zones, published by the American Horticultural Society, measure the average number of days per year above 86°F. Together they describe both ends of a plant's temperature tolerance. A plant rated 'USDA 5-9, AHS 9-2' tolerates winter cold typical of zones 5-9 and summer heat typical of heat zones 2-9.

Why does my plant tag only list a single zone like 'Zone 6'?

When a plant tag lists only a single zone (e.g., 'Zone 6' or 'Hardy to Zone 6'), it's specifying the coldest zone the plant can survive. The plant will also grow in any warmer zone, unless it has heat tolerance issues that the tag doesn't mention. For more confidence, look for tags that specify a range like 'Zones 6-9' — those tell you both the cold and heat boundaries.

USDA Plant Hardiness Zones: What Zone Am I In?