USDA Plant Hardiness Zone Map 2023
Planting Zone Finder: Find Your USDA Hardiness Zone by ZIP Code
Enter your 5-digit US ZIP code to instantly discover your USDA planting zone, the average minimum winter temperature for that zone, typical first and last frost dates, and how long your growing season runs. The lookup uses 2023 USDA Plant Hardiness Zone Map data aggregated to ZIP-code prefix level, and everything runs privately in your browser.
Find your planting zone
Your planting zone
- Average annual minimum temperature
- Typical first fall frost
- Typical last spring frost
- Typical growing season
- Zone range in your ZIP prefix
What your USDA planting zone means
A USDA planting zone answers one question: how cold does it get in winter where you live? The USDA Plant Hardiness Zone Map, maintained by the US Department of Agriculture with climate data from Oregon State University's PRISM Climate Group, divides the country by the average annual extreme minimum winter temperature - the coldest temperature you can expect in a typical year, averaged over 30 years. Each numbered zone spans 10 degrees Fahrenheit, and each is split into two 5-degree half-zones (a is the colder half, b the warmer half), giving 26 zones from 1a in far-north Alaska to 13b in lowland Puerto Rico.
Gardeners and nurseries use zones as a shared language for winter survival. When a plant tag says "hardy in zones 5 to 8," it means the plant reliably survives winters where the average coldest temperature stays within that band. Matching your zone to the tag is the fastest way to avoid buying perennials, shrubs, and fruit trees that will die in your first winter. Zones say nothing about summer heat, rainfall, humidity, or soil, so treat them as the first filter, not the whole plan.
The 2023 map update
The current map, released in November 2023, is built on 1991-2020 weather data from 13,412 stations - nearly twice as many as the 2012 edition. Roughly half the country shifted about one half-zone warmer, mostly from better data and newer climate normals rather than a single cause. Chicago moved from 6a to 6b, Philadelphia from 7b to 8a, and parts of the Pacific Northwest warmed a half-zone as well. If your zone looks different from what you remember, the 2023 map is the current standard, and this finder uses it.
How this ZIP lookup works - and its honest limits
This tool maps the first three digits of your ZIP code to the most common 2023 hardiness zone across all ZIP codes sharing that prefix, using the public PRISM-derived dataset published by the Frostline project. Prefix-level lookup is right for the large majority of addresses and answers instantly with no server involved.
It has real limits you should know. A 3-digit prefix can span mountains, valleys, lakeshores, and cities, so some prefixes cover two or three zones - the result card shows your prefix's full zone range so you can see when you are near a boundary. Microclimates matter too: a sheltered courtyard can run a half-zone warmer than an exposed hilltop a mile away. If you garden near a boundary or in steep terrain, confirm your exact address on the official USDA interactive map and ask a local nursery what thrives nearby.
USDA planting zones 1a to 13b: temperature, frost dates, and example cities
The table below lists all 26 half-zones with their average annual minimum temperature range, a verified example city, and typical frost timing. Frost dates are long-term typical values for each zone - your local dates can shift by two to three weeks, so check the Old Farmer's Almanac or your local extension service for exact dates.
| Zone | Min temp (°F) | Min temp (°C) | Example city (verified 2023) | Typical first frost | Typical last frost | Growing season |
|---|---|---|---|---|---|---|
| Zone 1a | -60 to -55 °F | -51.1 to -48.3 °C | far-north Alaska (ZIP 99720) | Aug 25 | Jun 20 | ~80 days |
| Zone 1b | -55 to -50 °F | -48.3 to -45.6 °C | interior Arctic Alaska (ZIP 99722) | Aug 28 | Jun 15 | ~85 days |
| Zone 2a | -50 to -45 °F | -45.6 to -42.8 °C | Prudhoe Bay, AK | Sep 1 | Jun 10 | ~95 days |
| Zone 2b | -45 to -40 °F | -42.8 to -40.0 °C | Utqiagvik, AK | Sep 5 | Jun 5 | ~100 days |
| Zone 3a | -40 to -35 °F | -40.0 to -37.2 °C | Fairbanks, AK | Sep 12 | May 28 | ~105 days |
| Zone 3b | -35 to -30 °F | -37.2 to -34.4 °C | International Falls, MN | Sep 18 | May 22 | ~115 days |
| Zone 4a | -30 to -25 °F | -34.4 to -31.7 °C | Minot, ND | Sep 25 | May 15 | ~135 days |
| Zone 4b | -25 to -20 °F | -31.7 to -28.9 °C | Helena, MT | Oct 1 | May 8 | ~140 days |
| Zone 5a | -20 to -15 °F | -28.9 to -26.1 °C | St. Paul, MN | Oct 6 | May 2 | ~150 days |
| Zone 5b | -15 to -10 °F | -26.1 to -23.3 °C | Des Moines, IA | Oct 12 | Apr 27 | ~160 days |
| Zone 6a | -10 to -5 °F | -23.3 to -20.6 °C | Amherst, MA | Oct 18 | Apr 20 | ~175 days |
| Zone 6b | -5 to 0 °F | -20.6 to -17.8 °C | Detroit, MI | Oct 24 | Apr 22 | ~180 days |
| Zone 7a | 0 to 5 °F | -17.8 to -15.0 °C | Boise, ID | Oct 28 | Apr 12 | ~190 days |
| Zone 7b | 5 to 10 °F | -15.0 to -12.2 °C | New York, NY | Nov 5 | Apr 8 | ~200 days |
| Zone 8a | 10 to 15 °F | -12.2 to -9.4 °C | Washington, DC | Nov 12 | Mar 28 | ~210 days |
| Zone 8b | 15 to 20 °F | -9.4 to -6.7 °C | Portland, OR | Nov 20 | Mar 18 | ~225 days |
| Zone 9a | 20 to 25 °F | -6.7 to -3.9 °C | San Antonio, TX | Nov 28 | Mar 5 | ~235 days |
| Zone 9b | 25 to 30 °F | -3.9 to -1.1 °C | Houston, TX | Dec 8 | Feb 25 | ~260 days |
| Zone 10a | 30 to 35 °F | -1.1 to 1.7 °C | Phoenix, AZ | Dec 25 | Feb 8 | ~310 days |
| Zone 10b | 35 to 40 °F | 1.7 to 4.4 °C | Beverly Hills, CA | rare | rare | ~365 days |
| Zone 11a | 40 to 45 °F | 4.4 to 7.2 °C | Miami Beach, FL | none | none | 365 days |
| Zone 11b | 45 to 50 °F | 7.2 to 10.0 °C | Key West, FL | none | none | 365 days |
| Zone 12a | 50 to 55 °F | 10.0 to 12.8 °C | upland Puerto Rico (ZIP 00720) | none | none | 365 days |
| Zone 12b | 55 to 60 °F | 12.8 to 15.6 °C | Honolulu, HI | none | none | 365 days |
| Zone 13a | 60 to 65 °F | 15.6 to 18.3 °C | San Juan, PR | none | none | 365 days |
| Zone 13b | 65 to 70 °F | 18.3 to 21.1 °C | lowland Puerto Rico (ZIP 00979) | none | none | 365 days |
Worked examples: ZIP code to planting zone
- 90210 (Beverly Hills, CA) → Zone 10b. Average winter lows of 35 to 40°F (1.7 to 4.4°C). Frost is rare, so tropical plants grow outdoors year-round; summer heat and drought are the real constraints.
- 10001 (New York, NY) → Zone 7b. Winter lows of 5 to 10°F (minus 15 to minus 12.2°C). Long season of about 200 days with a typical last frost near April 8 and first frost near November 5.
- 60601 (Chicago, IL) → Zone 6a. The 606 prefix's most common 2023 zone is 6a (much of the metro and suburbs). Note the honest edge case: the exact 60601 ZIP sits in 6b in the raw data thanks to the downtown heat island - a half-zone reminder that prefix lookups are approximations near boundaries.
- 20001 (Washington, DC) → Zone 8a. Winter lows of 10 to 15°F (minus 12.2 to minus 9.4°C), up from 7b on the 2012 map. Citrus stays marginal, but palms and gardenias are comfortable.
- 96815 (Honolulu, HI) → Zone 12b. Winter lows of 55 to 60°F (12.8 to 15.6°C). No frost ever; heat, humidity, and drainage decide what thrives.
- 99501 (Anchorage, AK) → Zone 5a. Winter lows of minus 20 to minus 15°F (minus 28.9 to minus 26.1°C). The 995 prefix spans a wide range (2a-8b) across Alaska, so rural addresses should confirm on the official map.
Practical tips by zone group
Zones 1-4: the far north
- Stretch the short season with cold frames, row cover, and greenhouses; start seeds indoors 6-8 weeks before the last frost.
- Choose varieties rated at least one zone colder than yours as insurance against test winters.
- Mulch perennials heavily after the ground freezes and protect graft unions on fruit trees.
Zones 5-6: cold-temperate
- Time everything off your last spring frost date, not the calendar - a late freeze kills warm-season transplants.
- Fall-plant garlic, spring bulbs, and bare-root trees; winter mulch for marginally hardy perennials.
- Take advantage of real winter chill: apples, cherries, lilacs, and peonies need it to bloom well.
Zones 7-8: mild-temperate
- Garden through winter with kale, carrots, garlic, and cover crops - the ground rarely freezes hard.
- Watch chill hours for fruit trees; low-chill varieties of peaches and blueberries outperform northern types.
- Plant trees and shrubs in fall so roots establish over the mild winter.
Zones 9-10: subtropical
- Shift the main planting season to fall and late winter; summer heat stalls cool-season crops.
- Water deeply but infrequently to push roots down; mulch to keep soil cool.
- Keep frost cloth handy - one hard freeze a decade can still kill unprotected citrus and bougainvillea.
Zones 11-13: tropical
- There is no winter kill, so garden year-round - but there is also no winter reset for pests and disease; rotate crops and clean up debris.
- Prioritize drainage; tropical downpours rot roots faster than any cold snap.
- Choose heat-adapted varieties - temperate lettuce and spinach bolt in weeks.
Frequently asked questions
What is a USDA planting zone?
A USDA planting zone, also called a hardiness zone or growing zone, is a geographic area defined by its average annual extreme minimum winter temperature. The USDA Plant Hardiness Zone Map divides the United States into 13 zones, each spanning 10 degrees Fahrenheit, and each zone is split into two 5-degree half-zones labeled a and b, for 26 zones from 1a (minus 60 to minus 55 F) to 13b (65 to 70 F).
How do I find my planting zone by ZIP code?
Enter your 5-digit US ZIP code in the finder above. The tool maps the first three digits of your ZIP to the most common USDA 2023 hardiness zone in that prefix area and shows the zone's temperature range, typical frost dates, and growing-season length. It takes one second and nothing leaves your browser.
What changed in the 2023 USDA hardiness zone map?
The 2023 map is based on 30 years of weather data (1991 to 2020) from 13,412 weather stations, versus 1976 to 2005 data in the 2012 map. About half of the United States shifted one half-zone warmer. For example, Chicago moved from 6a to 6b and Philadelphia moved from 7b to 8a. This tool uses the 2023 map data.
How accurate is a ZIP code zone lookup?
This tool looks up the most common 2023 zone for your ZIP code's 3-digit prefix, which is correct for the large majority of addresses. Near zone boundaries, mountains, lakeshores, and urban heat islands, your exact street can sit a half-zone off - Chicago's Loop (60601) is a classic example. Treat the result as a strong starting point and confirm borderline cases on the official USDA interactive map.
Do planting zones tell me when to plant?
No. Zones only measure winter cold tolerance - whether a perennial plant can survive your winter. When to sow or transplant is driven by frost dates and soil temperature, which is why this tool also shows typical first and last frost dates for your zone.
What is the difference between zone 7a and 7b?
Half-zones split each 10-degree zone into two 5-degree bands. Zone 7a averages winter lows of 0 to 5 F, while 7b averages 5 to 10 F. That 5-degree difference decides whether marginally hardy plants like some camellias, figs, and palms survive an average winter.
Can I grow plants rated for a warmer zone than mine?
Sometimes. Microclimates near south-facing walls, urban heat, heavy mulch, and winter wrapping can push a plant about one half-zone warmer. You can also grow tender plants as annuals or in containers you move indoors. But a plant rated two or more zones warmer will usually die in a normal winter.
Do hardiness zones account for summer heat?
No. USDA zones ignore summer heat, humidity, rainfall, and day length entirely. A zone 8 garden in humid Georgia and a zone 8 garden in dry Oregon need very different plant choices. The American Horticultural Society heat-zone map, which counts days above 86 F, is the usual companion reference for heat tolerance.
Why does another website show a different zone for my ZIP?
Three common reasons: it still uses the older 2012 map, your address sits right on a half-zone boundary where sources legitimately disagree, or it uses a different data source. The USDA updated the official map in 2023, so 2023-based results are the current standard.
Are planting zones, hardiness zones, and growing zones the same thing?
Yes. Planting zone, hardiness zone, growing zone, and gardening zone all refer to the USDA Plant Hardiness Zone Map. Nurseries and seed packets usually print it as something like Zone 5 to 8, meaning the plant is reliably hardy across that range.
Do USDA zones work outside the United States?
The official map covers the United States including Alaska, Hawaii, and Puerto Rico. The same temperature-band system is widely used informally in Canada and by gardeners worldwide, but other countries have their own official maps and the bands do not account for local rainfall or summer patterns.
What should I do after learning my zone?
Use it as a filter, not a plan. Check plant tags for a hardiness range that includes your zone, then refine with your typical last spring frost date before sowing, your first fall frost date before planting fall crops, and local extension-service guidance for varieties proven in your area.
Data sources and methodology
Zone assignments use the USDA Plant Hardiness Zone Map 2023 dataset via the PRISM Climate Group, as published in bulk by the Frostline project (MIT license, dataset generated 2026-08-24, 40,283 ZIP codes). Each 3-digit ZIP prefix is assigned its modal (most common) half-zone across the ZIP codes in that prefix; the result card also shows the full zone range of the prefix and flags prefixes where the modal zone covers less than 60% of ZIP codes. Example cities in the zone table were verified individually against the same dataset. Typical frost dates are long-term approximate values per zone - confirm exact dates with the Old Farmer's Almanac or your local cooperative extension service. This tool is for gardening guidance, not a substitute for the official USDA interactive map on borderline sites.
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