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

Planting zone for 08557 — Sergeantsville, NJ

ZIP code 08557 (Sergeantsville, Hunterdon County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 16 and the first fall frost October 19.

Where ZIP 08557 is

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.

Zone7a0 to 5 °F
Coldest night−17.8 to −15 °C
Last frostApr 16
First frostOct 19
2012 zone6b

Was 6b 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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Sergeantsville, NJ…

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 Sergeantsville, NJ

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 16median — 50% chance of a later frost
Safe for tender plantsApril 30only 10% chance of frost after
First fall frostOctober 19median — 10% chance by Oct 4
Growing season185 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 3 and returns around November 1.

From the NOAA station Lambertville, NJ — 6 miles away, elevation 69 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 08557

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 5 – Mar 19
SpinachSow outdoors · Mar 5 – Mar 26
Broccoli, cabbageStart indoors · Feb 5 – Feb 19
Broccoli, cabbageTransplant · Mar 26 – Apr 9
Onion setsPlant outdoors · Mar 19 – Apr 2
PotatoesPlant outdoors · Mar 26 – Apr 9
LettuceSow outdoors · Mar 19 – Apr 2
Carrots, beetsSow outdoors · Mar 26 – Apr 9
TomatoesStart indoors · Feb 19 – Mar 5
TomatoesTransplant · Apr 23 – May 7
Peppers, eggplantStart indoors · Feb 5 – Feb 19
Peppers, eggplantTransplant · Apr 30 – May 14
BeansSow outdoors · Apr 23 – May 7
Sweet cornSow outdoors · Apr 23 – May 7
Cucumbers, squashSow outdoors · Apr 23 – May 7
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 16) 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 08557 came on Mar 31 — about the same time as the 1991–2020 average (Mar 30).

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 Sergeantsville, NJ

The soil mapped at the center of ZIP 08557 is Lansdale — loam, well drained.

TextureLoama good balance for most vegetables
pH4.8strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupBwater soaks in moderately
Farmland classprime farmlandUSDA classification

Map unit: Lansdale loam, 2 to 6 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 08557; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sergeantsville, NJ

Summer high88 °Faverage high, July
Winter low19 °Faverage low, January
Hot days30days a year at 90 °F or more
Freezing nights136nights a year at 32 °F or less
Growing degree days3,377base 50 °F — the season’s usable heat
Longest day15 h 04 mindaylight on June 21
Shortest day9 h 17 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation50.4 inper year, rain and melted snow
Snowfall13 inper year

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 42 °F, low 19 °F 42°19° JanFebruary: average high 44 °F, low 22 °F 44°22° FebMarch: average high 52 °F, low 29 °F 52°29° MarApril: average high 64 °F, low 39 °F 64°39° AprMay: average high 74 °F, low 49 °F 74°49° MayJune: average high 83 °F, low 58 °F 83°58° JunJuly: average high 88 °F, low 64 °F 88°64° JulAugust: average high 87 °F, low 61 °F 87°61° AugSeptember: average high 80 °F, low 54 °F 80°54° SepOctober: average high 68 °F, low 40 °F 68°40° OctNovember: average high 56 °F, low 32 °F 56°32° NovDecember: average high 46 °F, low 25 °F 46°25° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 3.65 in precipitation, 5.8 in snowfall 3.6❄6 JanFebruary: 2.86 in precipitation, 2.4 in snowfall 2.9❄2 FebMarch: 4.33 in precipitation, 2.6 in snowfall 4.3❄3 MarApril: 3.81 in precipitation, 0.2 in snowfall 3.8 AprMay: 4.32 in precipitation 4.3 MayJune: 4.78 in precipitation 4.8 JunJuly: 5.11 in precipitation 5.1 JulAugust: 4.69 in precipitation 4.7 AugSeptember: 4.44 in precipitation 4.4 SepOctober: 4.26 in precipitation 4.3 OctNovember: 3.50 in precipitation, 0.2 in snowfall 3.5 NovDecember: 4.61 in precipitation, 2.2 in snowfall 4.6❄2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Lambertville, NJ (6 mi away); precipitation: Lambertville, NJ (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

085597a
Stockton, NJ · 2 mi
085307a
Lambertville, NJ · 6 mi
085517a
Ringoes, NJ · 6 mi
189637a
Solebury, PA · 6 mi
189337a
Lumberville, PA · 6 mi
088037a
Baptistown, NJ · 6 mi
088257a
Frenchtown, NJ · 6 mi
189507a
Point Pleasant, PA · 7 mi

New Jersey planting zones →

Questions about 08557

What planting zone is ZIP code 08557?

ZIP code 08557 (Sergeantsville, NJ) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Sergeantsville, NJ?

The median last spring frost (32 °F) near 08557 is April 16; after April 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Lambertville station.

When is the first frost in Sergeantsville, NJ?

The median first fall frost near 08557 is October 19, giving a median frost-free growing season of 185 days.

When should I plant tomatoes in 08557?

Start tomato seeds indoors around Feb 19 – Mar 5 and set transplants outside around Apr 23 – May 7, one to three weeks after the median last frost.

How much rain and snow does 08557 get?

About 50.4 inches of precipitation a year and 13 inches of snowfall (NOAA 1991–2020 normals, Lambertville station).

How hot do summers get in Sergeantsville, NJ?

The average high peaks at 88 °F in July, with about 30 days a year at 90 °F or more.

What kind of soil does 08557 have?

The USDA soil survey maps Lansdale at the center of ZIP 08557: loam, well drained, pH about 4.8 (strongly acidic).

Did spring come early in Sergeantsville, NJ in 2026?

Spring leaf-out near 08557 came on Mar 31 in 2026, about the same as the 1991–2020 average (Mar 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Sergeantsville, NJ?

Long-day onions: the longest day near 08557 is 15 h 04 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 08557 change?

Yes. The 2012 USDA map put 08557 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.