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

Planting zone for 08628 — Trenton, NJ

ZIP code 08628 (Trenton, Mercer County) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is April 10 and the first fall frost November 1.

Where ZIP 08628 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.

Zone7b5 to 10 °F

Coldest night−15 to −12.2 °C

Last frostApr 10

First frostNov 1

2012 zone7a

Was 7a 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 7b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Trenton, 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 Trenton, NJ

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 10median — 50% chance of a later frost

Safe for tender plantsApril 25only 10% chance of frost after

First fall frostNovember 1median — 10% chance by Oct 15

Growing season202 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 31 and returns around November 12.

From the NOAA station Trenton Mercer Co. Airport, NJ — within 1 mile, elevation 184 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 08628

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 27 – Mar 13

SpinachSow outdoors · Feb 27 – Mar 20

Broccoli, cabbageStart indoors · Jan 30 – Feb 13

Broccoli, cabbageTransplant · Mar 20 – Apr 3

Onion setsPlant outdoors · Mar 13 – Mar 27

PotatoesPlant outdoors · Mar 20 – Apr 3

LettuceSow outdoors · Mar 13 – Mar 27

Carrots, beetsSow outdoors · Mar 20 – Apr 3

TomatoesStart indoors · Feb 13 – Feb 27

TomatoesTransplant · Apr 17 – May 1

Peppers, eggplantStart indoors · Jan 30 – Feb 13

Peppers, eggplantTransplant · Apr 24 – May 8

BeansSow outdoors · Apr 17 – May 1

Sweet cornSow outdoors · Apr 17 – May 1

Cucumbers, squashSow outdoors · Apr 17 – May 1

Fall lettuce, spinachSow outdoors · Sep 6 – Sep 20

GarlicPlant cloves · Oct 18 – Nov 22

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 10) and first fall frost (Nov 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 08628 came on Mar 22 — about the same time as the 1991–2020 average (Mar 22).

average
Mar 222026
Mar 22

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 7b in New Jersey

605 plants native to the lower 48 states, recorded in New Jersey, and rated by the USDA to survive 5 °F or colder — the bottom of zone 7b. 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 Trenton, NJ.

Soil in Trenton, NJ

The soil mapped at the center of ZIP 08628 is Quakertown — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH5.6moderately acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupCwater soaks in slowly

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Quakertown silt loam, 6 to 12 percent slopes, eroded.

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 08628; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Trenton, NJ

Summer high86 °Faverage high, July

Winter low24 °Faverage low, January

Hot days22days a year at 90 °F or more

Freezing nights97nights a year at 32 °F or less

Growing degree days3,551base 50 °F — the season’s usable heat

Longest day15 h 03 mindaylight on June 21

Shortest day9 h 18 mindaylight on December 21

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

Precipitation45.6 inper year, rain and melted snow

Snowfall27 inper year

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Trenton Mercer Co. Airport, NJ (within 1 mile); precipitation: Trenton Mercer Co. Airport, NJ (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

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

086187b

Trenton, NJ · 2 mi

189777b

Washington Crossing, PA · 3 mi

190677a

Morrisville, PA · 3 mi

086387a

Trenton, NJ · 3 mi

085607a

Titusville, NJ · 4 mi

085347a

Pennington, NJ · 5 mi

086097a

Trenton, NJ · 5 mi

190307a

Fairless Hills, PA · 6 mi

All 25 ZIP codes in Trenton → · New Jersey planting zones →

Questions about 08628

What planting zone is ZIP code 08628?

ZIP code 08628 (Trenton, NJ) is in USDA hardiness zone 7b on the 2023 map: the coldest night of an average winter reaches 5 to 10 °F (−15 to −12.2 °C).

When is the last frost in Trenton, NJ?

The median last spring frost (32 °F) near 08628 is April 10; after April 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Trenton Mercer Co. Airport station.

When is the first frost in Trenton, NJ?

The median first fall frost near 08628 is November 1, giving a median frost-free growing season of 202 days.

When should I plant tomatoes in 08628?

Start tomato seeds indoors around Feb 13 – Feb 27 and set transplants outside around Apr 17 – May 1, one to three weeks after the median last frost.

How much rain and snow does 08628 get?

About 45.6 inches of precipitation a year and 27 inches of snowfall (NOAA 1991–2020 normals, Trenton Mercer Co. Airport station).

How hot do summers get in Trenton, NJ?

The average high peaks at 86 °F in July, with about 22 days a year at 90 °F or more.

What kind of soil does 08628 have?

The USDA soil survey maps Quakertown at the center of ZIP 08628: silt loam, well drained, pH about 5.6 (moderately acidic).

Did spring come early in Trenton, NJ in 2026?

Spring leaf-out near 08628 came on Mar 22 in 2026, about the same as the 1991–2020 average (Mar 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Trenton, NJ?

Long-day onions: the longest day near 08628 is 15 h 03 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 08628 change?

Yes. The 2012 USDA map put 08628 in zone 7a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.