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

Planting zone for 03242 — Henniker, NH

ZIP code 03242 (Henniker, Merrimack County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 6 and the first fall frost October 1.

Where ZIP 03242 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 6
First frostOct 1
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 Henniker, 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 Henniker, NH

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 6median — 50% chance of a later frost
Safe for tender plantsMay 20only 10% chance of frost after
First fall frostOctober 1median — 10% chance by Sep 20
Growing season146 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 27 and returns around October 11.

From the NOAA station Hopkinton Lake, NH — 4 miles away, elevation 430 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 03242

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 25 – Apr 8
SpinachSow outdoors · Mar 25 – Apr 15
Broccoli, cabbageStart indoors · Feb 25 – Mar 11
Broccoli, cabbageTransplant · Apr 15 – Apr 29
Onion setsPlant outdoors · Apr 8 – Apr 22
PotatoesPlant outdoors · Apr 15 – Apr 29
LettuceSow outdoors · Apr 8 – Apr 22
Carrots, beetsSow outdoors · Apr 15 – Apr 29
TomatoesStart indoors · Mar 11 – Mar 25
TomatoesTransplant · May 13 – May 27
Peppers, eggplantStart indoors · Feb 25 – Mar 11
Peppers, eggplantTransplant · May 20 – Jun 3
BeansSow outdoors · May 13 – May 27
Sweet cornSow outdoors · May 13 – May 27
Cucumbers, squashSow outdoors · May 13 – May 27
Fall lettuce, spinachSow outdoors · Aug 6 – Aug 20
GarlicPlant cloves · Sep 17 – Oct 22
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 6) and first fall frost (Oct 1) 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 03242 came on Apr 15 — 3 days earlier than the 1991–2020 average (Apr 18).

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.

Trees 53

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 96

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falpine bearberry0.5 ft · blooms early spring · medium shade tolerance · to −62 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °F

Wildflowers & perennials 167

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °F

Grasses 141

alpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °FAmerican beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 6

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °FVirginia creeper1 ft · blooms late spring · medium shade tolerance · to −28 °F

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 Henniker, NH.

Soil in Henniker, NH

The soil mapped at the center of ZIP 03242 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 classFarmland of local importanceUSDA 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 03242; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Henniker, NH

Summer high83 °Faverage high, July
Winter low11 °Faverage low, February
Hot days11days a year at 90 °F or more
Freezing nights171nights a year at 32 °F or less
Growing degree days2,294base 50 °F — the season’s usable heat
Longest day15 h 23 mindaylight on June 21
Shortest day8 h 59 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation48 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 32 °F, low 13 °F 32°13° JanFebruary: average high 36 °F, low 11 °F 36°11° FebMarch: average high 43 °F, low 20 °F 43°20° MarApril: average high 57 °F, low 32 °F 57°32° AprMay: average high 69 °F, low 43 °F 69°43° MayJune: average high 77 °F, low 52 °F 77°52° JunJuly: average high 83 °F, low 58 °F 83°58° JulAugust: average high 81 °F, low 56 °F 81°56° AugSeptember: average high 74 °F, low 47 °F 74°47° SepOctober: average high 60 °F, low 37 °F 60°37° OctNovember: average high 47 °F, low 28 °F 47°28° NovDecember: average high 37 °F, low 19 °F 37°19° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 3.32 in precipitation 3.3 JanFebruary: 3.07 in precipitation 3.1 FebMarch: 3.75 in precipitation 3.8 MarApril: 3.85 in precipitation 3.9 AprMay: 3.67 in precipitation 3.7 MayJune: 4.48 in precipitation 4.5 JunJuly: 4.28 in precipitation 4.3 JulAugust: 4.01 in precipitation 4.0 AugSeptember: 4.00 in precipitation 4.0 SepOctober: 5.43 in precipitation 5.4 OctNovember: 3.86 in precipitation 3.9 NovDecember: 4.31 in precipitation 4.3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Hopkinton Lake, NH (4 mi away); precipitation: Hopkinton Lake, NH (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

032446a
Hillsborough, NH · 6 mi
032295b
Contoocook, NH · 7 mi
032215b
Bradford, NH · 9 mi
032816a
Weare, NH · 9 mi
032785b
Warner, NH · 10 mi
032735b
South Sutton, NH · 10 mi
034406a
Antrim, NH · 10 mi
034425b
Bennington, NH · 11 mi

New Hampshire planting zones →

Questions about 03242

What planting zone is ZIP code 03242?

ZIP code 03242 (Henniker, 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 Henniker, NH?

The median last spring frost (32 °F) near 03242 is May 6; after May 20 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Hopkinton Lake station.

When is the first frost in Henniker, NH?

The median first fall frost near 03242 is October 1, giving a median frost-free growing season of 146 days.

When should I plant tomatoes in 03242?

Start tomato seeds indoors around Mar 11 – Mar 25 and set transplants outside around May 13 – May 27, one to three weeks after the median last frost.

How much rain and snow does 03242 get?

About 48 inches of precipitation a year (NOAA 1991–2020 normals, Hopkinton Lake station).

How hot do summers get in Henniker, NH?

The average high peaks at 83 °F in July, with about 11 days a year at 90 °F or more.

What kind of soil does 03242 have?

The USDA soil survey maps Peru at the center of ZIP 03242: moderately decomposed plant material, moderately well drained, pH about 4.9 (strongly acidic).

Did spring come early in Henniker, NH in 2026?

Spring leaf-out near 03242 came on Apr 15 in 2026, 3 days earlier than the 1991–2020 average (Apr 18), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Henniker, NH?

Long-day onions: the longest day near 03242 is 15 h 23 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 03242 change?

Yes. The 2012 USDA map put 03242 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.