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

Planting zone for 18921 — Ferndale, PA

ZIP code 18921 (Ferndale, Bucks County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 29 and the first fall frost October 16.

Where ZIP 18921 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 29
First frostOct 16
2012 zone6b

Same zone as on the 2012 map. 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 Ferndale, PA…

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 Ferndale, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 29median — 50% chance of a later frost
Safe for tender plantsMay 15only 10% chance of frost after
First fall frostOctober 16median — 10% chance by Oct 4
Growing season170 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 17 and returns around October 28.

From the NOAA station Bucksville, PA — 2 miles away, elevation 387 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 18921

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 18 – Apr 1
SpinachSow outdoors · Mar 18 – Apr 8
Broccoli, cabbageStart indoors · Feb 18 – Mar 4
Broccoli, cabbageTransplant · Apr 8 – Apr 22
Onion setsPlant outdoors · Apr 1 – Apr 15
PotatoesPlant outdoors · Apr 8 – Apr 22
LettuceSow outdoors · Apr 1 – Apr 15
Carrots, beetsSow outdoors · Apr 8 – Apr 22
TomatoesStart indoors · Mar 4 – Mar 18
TomatoesTransplant · May 6 – May 20
Peppers, eggplantStart indoors · Feb 18 – Mar 4
Peppers, eggplantTransplant · May 13 – May 27
BeansSow outdoors · May 6 – May 20
Sweet cornSow outdoors · May 6 – May 20
Cucumbers, squashSow outdoors · May 6 – May 20
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 29) 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 18921 came on Mar 31 — about the same time as the 1991–2020 average (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 6b in Pennsylvania

605 plants native to the lower 48 states, recorded in Pennsylvania, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. Each links to its USDA PLANTS profile.

Trees 76

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 122

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 209

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 licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 173

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °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 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °F

Vines 10

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Fgraybark grape50 ft · blooms late spring · medium shade tolerance · to −8 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °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 Ferndale, PA.

Soil in Ferndale, PA

The soil mapped at the center of ZIP 18921 is Neshaminy — gravelly silt loam, well drained.

TextureGravelly silt loama good balance for most vegetables
pH5.4strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter4%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Neshaminy gravelly silt loam, 25 to 60 percent slopes, extremely bouldery.

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 18921; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Ferndale, PA

Summer high85 °Faverage high, July
Winter low19 °Faverage low, January
Hot days17days a year at 90 °F or more
Freezing nights139nights a year at 32 °F or less
Growing degree days3,107base 50 °F — the season’s usable heat
Longest day15 h 04 mindaylight on June 21
Shortest day9 h 16 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation51 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 39 °F, low 19 °F 39°19° JanFebruary: average high 41 °F, low 20 °F 41°20° FebMarch: average high 50 °F, low 28 °F 50°28° MarApril: average high 63 °F, low 39 °F 63°39° AprMay: average high 72 °F, low 49 °F 72°49° MayJune: average high 80 °F, low 58 °F 80°58° JunJuly: average high 85 °F, low 63 °F 85°63° JulAugust: average high 82 °F, low 61 °F 82°61° AugSeptember: average high 76 °F, low 54 °F 76°54° SepOctober: average high 65 °F, low 42 °F 65°42° OctNovember: average high 54 °F, low 31 °F 54°31° NovDecember: average high 43 °F, low 25 °F 43°25° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 3.61 in precipitation 3.6 JanFebruary: 3.00 in precipitation 3.0 FebMarch: 3.70 in precipitation 3.7 MarApril: 3.92 in precipitation 3.9 AprMay: 4.43 in precipitation 4.4 MayJune: 4.26 in precipitation 4.3 JunJuly: 5.75 in precipitation 5.8 JulAugust: 4.82 in precipitation 4.8 AugSeptember: 4.60 in precipitation 4.6 SepOctober: 5.09 in precipitation 5.1 OctNovember: 3.26 in precipitation 3.3 NovDecember: 4.54 in precipitation 4.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Bucksville, PA (2 mi away); precipitation: Bucksville, PA (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

189536b
Revere, PA · 1 mi
189306b
Kintnersville, PA · 2 mi
189726b
Upper Black Eddy, PA · 2 mi
189426b
Ottsville, PA · 4 mi
180397a
Durham, PA · 4 mi
180777a
Riegelsville, PA · 4 mi
189207a
Erwinna, PA · 5 mi
088487a
Milford, NJ · 6 mi

Pennsylvania planting zones →

Questions about 18921

What planting zone is ZIP code 18921?

ZIP code 18921 (Ferndale, PA) 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 Ferndale, PA?

The median last spring frost (32 °F) near 18921 is April 29; after May 15 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Bucksville station.

When is the first frost in Ferndale, PA?

The median first fall frost near 18921 is October 16, giving a median frost-free growing season of 170 days.

When should I plant tomatoes in 18921?

Start tomato seeds indoors around Mar 4 – Mar 18 and set transplants outside around May 6 – May 20, one to three weeks after the median last frost.

How much rain and snow does 18921 get?

About 51 inches of precipitation a year (NOAA 1991–2020 normals, Bucksville station).

How hot do summers get in Ferndale, PA?

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 18921 have?

The USDA soil survey maps Neshaminy at the center of ZIP 18921: gravelly silt loam, well drained, pH about 5.4 (strongly acidic).

Did spring come early in Ferndale, PA in 2026?

Spring leaf-out near 18921 came on Mar 31 in 2026, about the same as the 1991–2020 average (Mar 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Ferndale, PA?

Long-day onions: the longest day near 18921 is 15 h 04 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).