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

Planting zone for 04861 — Thomaston, ME

ZIP code 04861 (Thomaston, Knox County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 27 and the first fall frost October 19.

Where ZIP 04861 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.

Zone6a−10 to −5 °F

Coldest night−23.3 to −20.6 °C

Last frostApr 27

First frostOct 19

2012 zone5b

Was 5b on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Thomaston, 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 Thomaston, ME

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 27median — 50% chance of a later frost

Safe for tender plantsMay 9only 10% chance of frost after

First fall frostOctober 19median — 10% chance by Oct 5

Growing season175 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 15 and returns around October 31.

From the NOAA station W Rockport 1 Nnw, ME — 6 miles away, elevation 361 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 04861

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 16 – Mar 30

SpinachSow outdoors · Mar 16 – Apr 6

Broccoli, cabbageStart indoors · Feb 16 – Mar 2

Broccoli, cabbageTransplant · Apr 6 – Apr 20

Onion setsPlant outdoors · Mar 30 – Apr 13

PotatoesPlant outdoors · Apr 6 – Apr 20

LettuceSow outdoors · Mar 30 – Apr 13

Carrots, beetsSow outdoors · Apr 6 – Apr 20

TomatoesStart indoors · Mar 2 – Mar 16

TomatoesTransplant · May 4 – May 18

Peppers, eggplantStart indoors · Feb 16 – Mar 2

Peppers, eggplantTransplant · May 11 – May 25

BeansSow outdoors · May 4 – May 18

Sweet cornSow outdoors · May 4 – May 18

Cucumbers, squashSow outdoors · May 4 – May 18

Fall lettuce, spinachSow outdoors · Aug 24 – Sep 7

GarlicPlant cloves · Oct 5 – Nov 9

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 27) and first fall frost (Oct 19) 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 04861 came on Apr 17 — 5 days earlier than the 1991–2020 average (Apr 22).

average
Apr 222026
Apr 17

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).

Soil in Thomaston, ME

The soil mapped at the center of ZIP 04861 is Peru — moderately decomposed plant material, moderately well drained.

TextureModerately decomposed plant materialtop layer

pH4.9strongly acidic; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter80%high

Hydrologic groupC/Dslow when drained; wet otherwise

Farmland classNot prime farmlandUSDA classification

Map unit: Peru fine sandy loam, 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 04861; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Thomaston, ME

Summer high77 °Faverage high, July

Winter low12 °Faverage low, January

Hot days2days a year at 90 °F or more

Freezing nights148nights a year at 32 °F or less

Growing degree days2,043base 50 °F — the season’s usable heat

Longest day15 h 30 mindaylight on June 21

Shortest day8 h 52 mindaylight on December 21

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

Precipitation56.2 inper year, rain and melted snow

Snowfall69 inper year

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: W Rockport 1 Nnw, ME (6 mi away); precipitation: W Rockport 1 Nnw, ME (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

2 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

South Thomaston, ME · 4 mi

West Rockport, ME · 6 mi

048596a

Spruce Head, ME · 8 mi

045636a

Cushing, ME · 8 mi

Maine planting zones →

Questions about 04861

What planting zone is ZIP code 04861?

ZIP code 04861 (Thomaston, ME) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Thomaston, ME?

The median last spring frost (32 °F) near 04861 is April 27; after May 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, W Rockport 1 Nnw station.

When is the first frost in Thomaston, ME?

The median first fall frost near 04861 is October 19, giving a median frost-free growing season of 175 days.

When should I plant tomatoes in 04861?

Start tomato seeds indoors around Mar 2 – Mar 16 and set transplants outside around May 4 – May 18, one to three weeks after the median last frost.

How much rain and snow does 04861 get?

About 56.2 inches of precipitation a year and 69 inches of snowfall (NOAA 1991–2020 normals, W Rockport 1 Nnw station).

How hot do summers get in Thomaston, ME?

The average high peaks at 77 °F in July, with about 2 days a year at 90 °F or more.

What kind of soil does 04861 have?

The USDA soil survey maps Peru at the center of ZIP 04861: moderately decomposed plant material, moderately well drained, pH about 4.9 (strongly acidic).

Did spring come early in Thomaston, ME in 2026?

Spring leaf-out near 04861 came on Apr 17 in 2026, 5 days earlier than the 1991–2020 average (Apr 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Thomaston, ME?

Long-day onions: the longest day near 04861 is 15 h 30 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 04861 change?

Yes. The 2012 USDA map put 04861 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.