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

Planting zone for 08542 — Princeton, NJ

ZIP code 08542 (Princeton, Mercer County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 25 and the first fall frost October 16.

Where ZIP 08542 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 25
First frostOct 16
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 Princeton, 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 Princeton, NJ

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 25median — 50% chance of a later frost
Safe for tender plantsMay 12only 10% chance of frost after
First fall frostOctober 16median — 10% chance by Oct 4
Growing season173 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 10 and returns around October 28.

From the NOAA station Hightstown 2 W, NJ — 8 miles away, elevation 102 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 08542

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 14 – Mar 28
SpinachSow outdoors · Mar 14 – Apr 4
Broccoli, cabbageStart indoors · Feb 14 – Feb 28
Broccoli, cabbageTransplant · Apr 4 – Apr 18
Onion setsPlant outdoors · Mar 28 – Apr 11
PotatoesPlant outdoors · Apr 4 – Apr 18
LettuceSow outdoors · Mar 28 – Apr 11
Carrots, beetsSow outdoors · Apr 4 – Apr 18
TomatoesStart indoors · Feb 28 – Mar 14
TomatoesTransplant · May 2 – May 16
Peppers, eggplantStart indoors · Feb 14 – Feb 28
Peppers, eggplantTransplant · May 9 – May 23
BeansSow outdoors · May 2 – May 16
Sweet cornSow outdoors · May 2 – May 16
Cucumbers, squashSow outdoors · May 2 – May 16
Fall lettuce, spinachSow outdoors · Aug 21 – Sep 4
GarlicPlant cloves · Oct 2 – Nov 6
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 25) and first fall frost (Oct 16) 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 08542 came on Mar 26 — about the same time as the 1991–2020 average (Mar 27).

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 7a in New Jersey

600 plants native to the lower 48 states, recorded in New Jersey, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. Each links to its USDA PLANTS profile.

Trees 80

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 119

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °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 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °F

Wildflowers & perennials 201

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °FAmerican speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °F

Grasses 175

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °FAmerican cupscale3 ft · blooms early summer · high shade tolerance · to −18 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °FAtlantic mannagrass3 ft · blooms summer · low shade tolerance · to −8 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °F

Vines 10

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °FAmerican wisteria50 ft · blooms spring · low shade tolerance · to −3 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °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 Princeton, NJ.

Soil in Princeton, NJ

The soil mapped at the center of ZIP 08542 is Udorthents — loam, moderately well drained.

TextureLoama good balance for most vegetables
pH4.6strongly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Udorthents, bedrock substratum, 0 to 8 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 08542; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Princeton, NJ

Summer high87 °Faverage high, July
Winter low21 °Faverage low, January
Hot days26days a year at 90 °F or more
Freezing nights114nights a year at 32 °F or less
Growing degree days3,272base 50 °F — the season’s usable heat
Longest day15 h 03 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)
Precipitation49.4 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 41 °F, low 21 °F 41°21° JanFebruary: average high 43 °F, low 23 °F 43°23° FebMarch: average high 51 °F, low 30 °F 51°30° MarApril: average high 63 °F, low 39 °F 63°39° AprMay: average high 73 °F, low 48 °F 73°48° MayJune: average high 82 °F, low 58 °F 82°58° JunJuly: average high 87 °F, low 63 °F 87°63° JulAugust: average high 85 °F, low 61 °F 85°61° AugSeptember: average high 78 °F, low 54 °F 78°54° SepOctober: average high 66 °F, low 42 °F 66°42° OctNovember: average high 55 °F, low 33 °F 55°33° NovDecember: average high 46 °F, low 27 °F 46°27° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 3.59 in precipitation 3.6 JanFebruary: 2.92 in precipitation 2.9 FebMarch: 4.39 in precipitation 4.4 MarApril: 3.81 in precipitation 3.8 AprMay: 4.22 in precipitation 4.2 MayJune: 4.67 in precipitation 4.7 JunJuly: 4.88 in precipitation 4.9 JulAugust: 4.48 in precipitation 4.5 AugSeptember: 4.30 in precipitation 4.3 SepOctober: 4.03 in precipitation 4.0 OctNovember: 3.42 in precipitation 3.4 NovDecember: 4.65 in precipitation 4.7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Hightstown 2 W, NJ (8 mi away); precipitation: Princeton 2.3 E, NJ (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

085417a
Princeton, NJ · <1 mi
085447a
Princeton, NJ · <1 mi
085407a
Princeton, NJ · <1 mi
085287a
Kingston, NJ · 3 mi
085537a
Rocky Hill, NJ · 3 mi
085367a
Plainsboro, NJ · 4 mi
085047a
Blawenburg, NJ · 4 mi
085587a
Skillman, NJ · 5 mi

All 5 ZIP codes in Princeton → · New Jersey planting zones →

Questions about 08542

What planting zone is ZIP code 08542?

ZIP code 08542 (Princeton, 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 Princeton, NJ?

The median last spring frost (32 °F) near 08542 is April 25; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Hightstown 2 W station.

When is the first frost in Princeton, NJ?

The median first fall frost near 08542 is October 16, giving a median frost-free growing season of 173 days.

When should I plant tomatoes in 08542?

Start tomato seeds indoors around Feb 28 – Mar 14 and set transplants outside around May 2 – May 16, one to three weeks after the median last frost.

How much rain and snow does 08542 get?

About 49.4 inches of precipitation a year (NOAA 1991–2020 normals, Princeton 2.3 E station).

How hot do summers get in Princeton, NJ?

The average high peaks at 87 °F in July, with about 26 days a year at 90 °F or more.

What kind of soil does 08542 have?

The USDA soil survey maps Udorthents at the center of ZIP 08542: loam, moderately well drained, pH about 4.6 (strongly acidic).

Did spring come early in Princeton, NJ in 2026?

Spring leaf-out near 08542 came on Mar 26 in 2026, about the same as the 1991–2020 average (Mar 27), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Princeton, NJ?

Long-day onions: the longest day near 08542 is 15 h 03 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 08542 change?

Yes. The 2012 USDA map put 08542 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.