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

Planting zone for 03851 — Milton, NH

ZIP code 03851 (Milton, Strafford County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 30 and the first fall frost October 9.

Where ZIP 03851 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 frostApr 30

First frostOct 9

2012 zone5a

Was 5a 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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Milton, NH…

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 Milton, NH

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 30median — 50% chance of a later frost

Safe for tender plantsMay 13only 10% chance of frost after

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

Growing season161 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 17 and returns around October 23.

From the NOAA station Rochester Skyhaven Airport, NH — 12 miles away, elevation 325 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 03851

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 19 – Apr 2

SpinachSow outdoors · Mar 19 – Apr 9

Broccoli, cabbageStart indoors · Feb 19 – Mar 5

Broccoli, cabbageTransplant · Apr 9 – Apr 23

Onion setsPlant outdoors · Apr 2 – Apr 16

PotatoesPlant outdoors · Apr 9 – Apr 23

LettuceSow outdoors · Apr 2 – Apr 16

Carrots, beetsSow outdoors · Apr 9 – Apr 23

TomatoesStart indoors · Mar 5 – Mar 19

TomatoesTransplant · May 7 – May 21

Peppers, eggplantStart indoors · Feb 19 – Mar 5

Peppers, eggplantTransplant · May 14 – May 28

BeansSow outdoors · May 7 – May 21

Sweet cornSow outdoors · May 7 – May 21

Cucumbers, squashSow outdoors · May 7 – May 21

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 (Apr 30) 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 03851 came on Apr 16 — about the same time as the 1991–2020 average (Apr 18).

average
Apr 182026
Apr 16

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 New Hampshire

475 plants native to the lower 48 states, recorded in New Hampshire, 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 Milton, NH.

Soil in Milton, NH

The soil mapped at the center of ZIP 03851 is Gloucester — extremely stony fine sandy loam, somewhat excessively drained.

TextureExtremely stony fine sandy loamdrains and warms fast; dries out and needs more feeding

pH4.8strongly acidic; most vegetables like 6.0–7.0

DrainageSomewhat excessively drainednatural drainage class

Organic matter1.35%low — add compost

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Gloucester extremely stony fine sandy loam, 8 to 25 percent slopes.

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 03851; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Milton, NH

Summer high82 °Faverage high, July

Winter low15 °Faverage low, January

Hot days11days a year at 90 °F or more

Freezing nights145nights a year at 32 °F or less

Growing degree days2,438base 50 °F — the season’s usable heat

Longest day15 h 25 mindaylight on June 21

Shortest day8 h 57 mindaylight on December 21

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

Precipitation51.1 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: Rochester Skyhaven Airport, NH (12 mi away); precipitation: Rochester, NH (10 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.

038875b

Union, NH · 4 mi

038525b

Milton Mills, NH · 4 mi

038356a

Farmington, NH · 5 mi

040275b

Lebanon, ME · 6 mi

038555b

New Durham, NH · 7 mi

New Hampshire planting zones →

Questions about 03851

What planting zone is ZIP code 03851?

ZIP code 03851 (Milton, NH) 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 Milton, NH?

The median last spring frost (32 °F) near 03851 is April 30; after May 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Rochester Skyhaven Airport station.

When is the first frost in Milton, NH?

The median first fall frost near 03851 is October 9, giving a median frost-free growing season of 161 days.

When should I plant tomatoes in 03851?

Start tomato seeds indoors around Mar 5 – Mar 19 and set transplants outside around May 7 – May 21, one to three weeks after the median last frost.

How much rain and snow does 03851 get?

About 51.1 inches of precipitation a year (NOAA 1991–2020 normals, Rochester station).

How hot do summers get in Milton, NH?

The average high peaks at 82 °F in July, with about 11 days a year at 90 °F or more.

What kind of soil does 03851 have?

The USDA soil survey maps Gloucester at the center of ZIP 03851: extremely stony fine sandy loam, somewhat excessively drained, pH about 4.8 (strongly acidic).

Did spring come early in Milton, NH in 2026?

Spring leaf-out near 03851 came on Apr 16 in 2026, about the same as the 1991–2020 average (Apr 18), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Milton, NH?

Long-day onions: the longest day near 03851 is 15 h 25 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 03851 change?

Yes. The 2012 USDA map put 03851 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.