What Growing Zone Is Maine In?

Last updated September 6, 2026

USDA hardiness zones

4a to 6a

2023 USDA Plant Hardiness Zone Map

Maine spans USDA hardiness zone 4a to 6a across its major population centers, according to the 2023 USDA Plant Hardiness Zone Map. That's a real range, not a single number: where you fall in it depends on where in the state you actually are.

Find your exact zone by ZIP code

Find your exact zone

US ZIP code

Your USDA hardiness zone

Zone 6b

Avg. annual minimum (°F)

-5°F to 0°F

Avg. annual minimum (°C)

-21°C to -18°C

Nearest reference point: Chicago, IL

This is a regional estimate based on the nearest of 826 reference points, each matched to the official 2023 USDA zone map. It’s accurate to within about a half-zone across most of the country, but elevation shifts zones over short distances, so if you’re in mountainous terrain, check the official USDA map for your exact address (see Sources below).

Maine's USDA Hardiness Zones

Here's how the zone shifts across Maine's major cities:

City	USDA Zone
Presque Isle	4a
Caribou	4a
Bangor	5a
Portland	6a

For your exact zone by ZIP code, use the Hardiness Zone Finder, and for what a zone number actually measures (and doesn't), see how zones actually work.

Frost Dates in Maine

Frost dates track zone, so they shift across Maine the same way the zone number does:

Aroostook County (Presque Isle, Caribou) (zone 4): average last frost Apr 23 - May 7, average first frost Sep 23 - Oct 7.
Coastal southern Maine (Portland) (zone 6): average last frost Mar 29 - Apr 12, average first frost Oct 18 - Nov 1.

These are averages, not guarantees. For your specific frost window, use the Frost Date Calculator. For a full vegetable-by-vegetable planting calendar already calculated from Maine's frost dates, see the Maine Planting Calendar.

Maine splits clearly between a milder coastal band and a much colder interior/northern band -- Portland sits in zone 6a while far-northern Aroostook County (Presque Isle, Caribou) drops to zone 4a, a difference University of Maine Extension attributes to both latitude and the coast's moderating effect.

What Grows Well in Maine's Zones

A few real, zone-appropriate picks recommended by University of Maine Cooperative Extension for Maine landscapes: not an exhaustive list, but a genuine starting point.

Pagoda dogwood (Cornus alternifolia)
Winterberry (Ilex verticillata)
Shadblow serviceberry (Amelanchier canadensis)
Northern bayberry (Myrica pensylvanica)
Common witchhazel (Hamamelis virginiana)
Staghorn sumac (Rhus typhina)

Ready to find your exact zone? Use the Hardiness Zone Finder: enter your ZIP code for a precise match against the 2023 USDA map.

Maine Growing Zone FAQ

What growing zone is Maine in?

Maine spans USDA hardiness zones 4a to 6a on the 2023 USDA Plant Hardiness Zone Map. Presque Isle is zone 4a and Caribou is zone 4a; enter your ZIP code in the Hardiness Zone Finder for your exact zone.

What growing zone is Presque Isle, ME?

Presque Isle is in USDA hardiness zone 4a on the 2023 USDA map. Zones within a city can differ by half a zone, so check your ZIP code for an exact match.

What growing zone is Caribou, ME?

Caribou is in USDA hardiness zone 4a on the 2023 USDA map. Zones within a city can differ by half a zone, so check your ZIP code for an exact match.

What growing zone is Bangor, ME?

Bangor is in USDA hardiness zone 5a on the 2023 USDA map. Zones within a city can differ by half a zone, so check your ZIP code for an exact match.

What growing zone is Portland, ME?

Portland is in USDA hardiness zone 6a on the 2023 USDA map. Zones within a city can differ by half a zone, so check your ZIP code for an exact match.

A home yard in coastal Maine, with spruce and fir trees, granite rocks and a cedar-shingled house, planted with pagoda dogwood, winterberry and shadblow serviceberry — Plants that suit Maine: pagoda dogwood, winterberry and shadblow serviceberry. AI-generated image.

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The Spacing & Planting Cheat Sheet

When to start, when to plant, how far apart.

Sources & further reading

Zone and city data checked against the official USDA Plant Hardiness Zone Map. Plant recommendations sourced from University of Maine Cooperative Extension. Climate note sourced from University of Maine Cooperative Extension. For more on how we build and verify reference data across this site, see our methodology page.

Growing zones in nearby states

Gardening near a state line? Zones don't stop at the border:

Or browse all 51 state growing-zone guides.