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

Planting zone for 07840 — Hackettstown, NJ

ZIP code 07840 (Hackettstown, Warren County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 25 and the first fall frost October 19.

Where ZIP 07840 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.

Zone6b−5 to 0 °F

Coldest night−20.6 to −17.8 °C

Last frostApr 25

First frostOct 19

2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Hackettstown, 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 Hackettstown, 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 11only 10% chance of frost after

First fall frostOctober 19median — 10% chance by Oct 5

Growing season175 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 11 and returns around October 31.

From the NOAA station Andover Aeroflex Airport, NJ — 11 miles away, elevation 584 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 07840

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 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 25) 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 07840 came on Apr 1 — 8 days earlier than the 1991–2020 average (Apr 9).

average
Apr 92026
Apr 1

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 6b in New Jersey

581 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 6b. 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 Hackettstown, NJ.

Soil in Hackettstown, NJ

The soil mapped at the center of ZIP 07840 is Hazen — slightly decomposed plant material, well drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureSlightly decomposed plant materialtop layer

DrainageWell drainednatural drainage class

Organic matter85%high

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Urban land-Hazen-Paulins Kill complex, 0 to 3 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 07840; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Hackettstown, NJ

Summer high84 °Faverage high, July

Winter low19 °Faverage low, January

Hot days11days a year at 90 °F or more

Freezing nights127nights a year at 32 °F or less

Growing degree days2,877base 50 °F — the season’s usable heat

Longest day15 h 07 mindaylight on June 21

Shortest day9 h 14 mindaylight on December 21

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

Precipitation49.5 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Andover Aeroflex Airport, NJ (11 mi away); precipitation: Hackettstown 0.8 W, NJ (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

078806b

Vienna, NJ · 3 mi

078706b

Schooleys Mountain, NJ · 4 mi

078286b

Budd Lake, NJ · 4 mi

078386b

Great Meadows, NJ · 5 mi

078206b

Allamuchy, NJ · 5 mi

078536b

Long Valley, NJ · 6 mi

078656b

Port Murray, NJ · 6 mi

078366b

Flanders, NJ · 6 mi

New Jersey planting zones →

Questions about 07840

What planting zone is ZIP code 07840?

ZIP code 07840 (Hackettstown, NJ) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Hackettstown, NJ?

The median last spring frost (32 °F) near 07840 is April 25; after May 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Andover Aeroflex Airport station.

When is the first frost in Hackettstown, NJ?

The median first fall frost near 07840 is October 19, giving a median frost-free growing season of 175 days.

When should I plant tomatoes in 07840?

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 07840 get?

About 49.5 inches of precipitation a year (NOAA 1991–2020 normals, Hackettstown 0.8 W station).

How hot do summers get in Hackettstown, NJ?

The average high peaks at 84 °F in July, with about 11 days a year at 90 °F or more.

What kind of soil does 07840 have?

The USDA soil survey maps Hazen at the center of ZIP 07840: slightly decomposed plant material, well drained.

Did spring come early in Hackettstown, NJ in 2026?

Spring leaf-out near 07840 came on Apr 1 in 2026, 8 days earlier than the 1991–2020 average (Apr 9), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Hackettstown, NJ?

Long-day onions: the longest day near 07840 is 15 h 07 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 07840 change?

Yes. The 2012 USDA map put 07840 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.