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

Planting zone for 07927 — Cedar Knolls, NJ

ZIP code 07927 (Cedar Knolls, Morris County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 17 and the first fall frost October 23.

Where ZIP 07927 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 17

First frostOct 23

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 Cedar Knolls, 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 Cedar Knolls, NJ

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 17median — 50% chance of a later frost

Safe for tender plantsMay 5only 10% chance of frost after

First fall frostOctober 23median — 10% chance by Oct 8

Growing season189 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 4 and returns around November 2.

From the NOAA station Boonton 1 Se, NJ — 6 miles away, elevation 279 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 07927

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 6 – Mar 20

SpinachSow outdoors · Mar 6 – Mar 27

Broccoli, cabbageStart indoors · Feb 6 – Feb 20

Broccoli, cabbageTransplant · Mar 27 – Apr 10

Onion setsPlant outdoors · Mar 20 – Apr 3

PotatoesPlant outdoors · Mar 27 – Apr 10

LettuceSow outdoors · Mar 20 – Apr 3

Carrots, beetsSow outdoors · Mar 27 – Apr 10

TomatoesStart indoors · Feb 20 – Mar 6

TomatoesTransplant · Apr 24 – May 8

Peppers, eggplantStart indoors · Feb 6 – Feb 20

Peppers, eggplantTransplant · May 1 – May 15

BeansSow outdoors · Apr 24 – May 8

Sweet cornSow outdoors · Apr 24 – May 8

Cucumbers, squashSow outdoors · Apr 24 – May 8

Fall lettuce, spinachSow outdoors · Aug 28 – Sep 11

GarlicPlant cloves · Oct 9 – Nov 13

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 17) and first fall frost (Oct 23) 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 07927 came on Mar 31 — about the same time as the 1991–2020 average (Apr 1).

average
Apr 12026
Mar 31

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.

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 Cedar Knolls, NJ.

Soil in Cedar Knolls, NJ

The soil mapped at the center of ZIP 07927 is Rockaway — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding

pH5.0strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Rockaway sandy loam, 8 to 15 percent slopes, very stony.

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 07927; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cedar Knolls, NJ

Summer high85 °Faverage high, July

Winter low21 °Faverage low, January

Hot days16days a year at 90 °F or more

Freezing nights124nights a year at 32 °F or less

Growing degree days3,151base 50 °F — the season’s usable heat

Longest day15 h 06 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: Boonton 1 Se, NJ (6 mi away); precipitation: Denville Twp 1.5 Ese, NJ (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

079817a

Whippany, NJ · 2 mi

079506b

Morris Plains, NJ · 2 mi

079637a

Morristown, NJ · 2 mi

079617a

Convent Station, NJ · 3 mi

070547a

Parsippany, NJ · 4 mi

079607a

Morristown, NJ · 4 mi

079327a

Florham Park, NJ · 5 mi

078346b

Denville, NJ · 5 mi

New Jersey planting zones →

Questions about 07927

What planting zone is ZIP code 07927?

ZIP code 07927 (Cedar Knolls, 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 Cedar Knolls, NJ?

The median last spring frost (32 °F) near 07927 is April 17; after May 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Boonton 1 Se station.

When is the first frost in Cedar Knolls, NJ?

The median first fall frost near 07927 is October 23, giving a median frost-free growing season of 189 days.

When should I plant tomatoes in 07927?

Start tomato seeds indoors around Feb 20 – Mar 6 and set transplants outside around Apr 24 – May 8, one to three weeks after the median last frost.

How much rain and snow does 07927 get?

About 49.5 inches of precipitation a year (NOAA 1991–2020 normals, Denville Twp 1.5 Ese station).

How hot do summers get in Cedar Knolls, NJ?

The average high peaks at 85 °F in July, with about 16 days a year at 90 °F or more.

What kind of soil does 07927 have?

The USDA soil survey maps Rockaway at the center of ZIP 07927: sandy loam, well drained, pH about 5.0 (strongly acidic).

Did spring come early in Cedar Knolls, NJ in 2026?

Spring leaf-out near 07927 came on Mar 31 in 2026, about the same as the 1991–2020 average (Apr 1), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Cedar Knolls, NJ?

Long-day onions: the longest day near 07927 is 15 h 06 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 07927 change?

Yes. The 2012 USDA map put 07927 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.