Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 04476 — Penobscot, ME

ZIP code 04476 (Penobscot, Hancock County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 8 and the first fall frost October 9.

Where ZIP 04476 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone5b−15 to −10 °F

Coldest night−26.1 to −23.3 °C

Last frostMay 8

First frostOct 9

2012 zone5b

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Penobscot, ME…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Penobscot, ME

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMay 8median — 50% chance of a later frost

Safe for tender plantsMay 23only 10% chance of frost after

First fall frostOctober 9median — 10% chance by Sep 27

Growing season152 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 27 and returns around October 21.

From the NOAA station E Surry, ME — 12 miles away, elevation 105 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 04476

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 27 – Apr 10

SpinachSow outdoors · Mar 27 – Apr 17

Broccoli, cabbageStart indoors · Feb 27 – Mar 13

Broccoli, cabbageTransplant · Apr 17 – May 1

Onion setsPlant outdoors · Apr 10 – Apr 24

PotatoesPlant outdoors · Apr 17 – May 1

LettuceSow outdoors · Apr 10 – Apr 24

Carrots, beetsSow outdoors · Apr 17 – May 1

TomatoesStart indoors · Mar 13 – Mar 27

TomatoesTransplant · May 15 – May 29

Peppers, eggplantStart indoors · Feb 27 – Mar 13

Peppers, eggplantTransplant · May 22 – Jun 5

BeansSow outdoors · May 15 – May 29

Sweet cornSow outdoors · May 15 – May 29

Cucumbers, squashSow outdoors · May 15 – May 29

Fall lettuce, spinachSow outdoors · Aug 14 – Aug 28

GarlicPlant cloves · Sep 25 – Oct 30

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 8) and first fall frost (Oct 9) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 04476 came on Apr 22 — about the same time as the 1991–2020 average (Apr 24).

average
Apr 242026
Apr 22

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 5b in Maine

493 plants native to the lower 48 states, recorded in Maine, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Penobscot, ME.

Soil in Penobscot, ME

The soil mapped at the center of ZIP 04476 is Brayton — muck, poorly drained.

TextureMucktop layer

pH4.0strongly acidic; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter53%high

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Brayton-Colonel association, 0 to 8 percent slopes, very stony.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 04476; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Penobscot, ME

Summer high77 °Faverage high, July

Winter low11 °Faverage low, January

Hot days1days a year at 90 °F or more

Freezing nights162nights a year at 32 °F or less

Growing degree days1,868base 50 °F — the season’s usable heat

Longest day15 h 33 mindaylight on June 21

Shortest day8 h 50 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation49.4 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: E Surry, ME (12 mi away); precipitation: E Surry, ME (12 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

049725b

Sandy Point, ME · 6 mi

044315b

East Orland, ME · 6 mi

Stockton Springs, ME · 7 mi

044215b

Castine, ME · 7 mi

046175b

Brooksville, ME · 8 mi

046845b

Surry, ME · 10 mi

Maine planting zones →

Questions about 04476

What planting zone is ZIP code 04476?

ZIP code 04476 (Penobscot, ME) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Penobscot, ME?

The median last spring frost (32 °F) near 04476 is May 8; after May 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, E Surry station.

When is the first frost in Penobscot, ME?

The median first fall frost near 04476 is October 9, giving a median frost-free growing season of 152 days.

When should I plant tomatoes in 04476?

Start tomato seeds indoors around Mar 13 – Mar 27 and set transplants outside around May 15 – May 29, one to three weeks after the median last frost.

How much rain and snow does 04476 get?

About 49.4 inches of precipitation a year (NOAA 1991–2020 normals, E Surry station).

How hot do summers get in Penobscot, ME?

The average high peaks at 77 °F in July, with about 1 days a year at 90 °F or more.

What kind of soil does 04476 have?

The USDA soil survey maps Brayton at the center of ZIP 04476: muck, poorly drained, pH about 4.0 (strongly acidic).

Did spring come early in Penobscot, ME in 2026?

Spring leaf-out near 04476 came on Apr 22 in 2026, about the same as the 1991–2020 average (Apr 24), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Penobscot, ME?

Long-day onions: the longest day near 04476 is 15 h 33 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).