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

Planting zone for 08502 — Belle Mead, NJ

ZIP code 08502 (Belle Mead, Somerset 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 27.

Where ZIP 08502 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.

Zone7a0 to 5 °F
Coldest night−17.8 to −15 °C
Last frostApr 16
First frostOct 27
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 Belle Mead, 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 Belle Mead, 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 plantsMay 1only 10% chance of frost after
First fall frostOctober 27median — 10% chance by Oct 10
Growing season192 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 3 and returns around November 7.

From the NOAA station Wertsville 4 Ne, NJ — 7 miles away, elevation 282 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 08502

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 · Sep 1 – Sep 15
GarlicPlant cloves · Oct 13 – Nov 17
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 16) and first fall frost (Oct 27) 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 08502 came on Mar 24 — about the same time as the 1991–2020 average (Mar 26).

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 Belle Mead, NJ

The soil mapped at the center of ZIP 08502 is Penn — channery silt loam, well drained.

TextureChannery silt loama good balance for most vegetables
pH4.6strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupCwater soaks in slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Penn channery silt loam, 6 to 12 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 08502; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Belle Mead, NJ

Summer high85 °Faverage high, July
Winter low22 °Faverage low, January
Hot days17days a year at 90 °F or more
Freezing nights118nights a year at 32 °F or less
Growing degree days3,232base 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)
Precipitation48.5 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 38 °F, low 22 °F 38°22° JanFebruary: average high 41 °F, low 23 °F 41°23° FebMarch: average high 50 °F, low 30 °F 50°30° MarApril: average high 62 °F, low 40 °F 62°40° AprMay: average high 71 °F, low 50 °F 71°50° MayJune: average high 80 °F, low 59 °F 80°59° JunJuly: average high 85 °F, low 64 °F 85°64° JulAugust: average high 83 °F, low 62 °F 83°62° AugSeptember: average high 77 °F, low 55 °F 77°55° SepOctober: average high 65 °F, low 44 °F 65°44° OctNovember: average high 54 °F, low 35 °F 54°35° NovDecember: average high 43 °F, low 28 °F 43°28° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.46 in precipitation 3.5 JanFebruary: 2.97 in precipitation 3.0 FebMarch: 4.40 in precipitation 4.4 MarApril: 3.82 in precipitation 3.8 AprMay: 4.13 in precipitation 4.1 MayJune: 4.27 in precipitation 4.3 JunJuly: 4.80 in precipitation 4.8 JulAugust: 4.55 in precipitation 4.5 AugSeptember: 4.25 in precipitation 4.3 SepOctober: 3.99 in precipitation 4.0 OctNovember: 3.38 in precipitation 3.4 NovDecember: 4.43 in precipitation 4.4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Wertsville 4 Ne, NJ (7 mi away); precipitation: Hillsborough Twp 3.5 Se, NJ (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

085537a
Rocky Hill, NJ · 3 mi
088447a
Hillsborough, NJ · 4 mi
085587a
Skillman, NJ · 4 mi
085047a
Blawenburg, NJ · 4 mi
085287a
Kingston, NJ · 5 mi
088237a
Franklin Park, NJ · 5 mi
088247a
Kendall Park, NJ · 6 mi
085407a
Princeton, NJ · 6 mi

New Jersey planting zones →

Questions about 08502

What planting zone is ZIP code 08502?

ZIP code 08502 (Belle Mead, 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 Belle Mead, NJ?

The median last spring frost (32 °F) near 08502 is April 16; after May 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Wertsville 4 Ne station.

When is the first frost in Belle Mead, NJ?

The median first fall frost near 08502 is October 27, giving a median frost-free growing season of 192 days.

When should I plant tomatoes in 08502?

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 08502 get?

About 48.5 inches of precipitation a year (NOAA 1991–2020 normals, Hillsborough Twp 3.5 Se station).

How hot do summers get in Belle Mead, NJ?

The average high peaks at 85 °F in July, with about 17 days a year at 90 °F or more.

What kind of soil does 08502 have?

The USDA soil survey maps Penn at the center of ZIP 08502: channery silt loam, well drained, pH about 4.6 (strongly acidic).

Did spring come early in Belle Mead, NJ in 2026?

Spring leaf-out near 08502 came on Mar 24 in 2026, about the same as the 1991–2020 average (Mar 26), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Belle Mead, NJ?

Long-day onions: the longest day near 08502 is 15 h 04 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 08502 change?

Yes. The 2012 USDA map put 08502 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.