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

Planting zone for 18411 — Clarks Summit, PA

ZIP code 18411 (Clarks Summit, Lackawanna County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 23 and the first fall frost October 20.

Where ZIP 18411 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.

Zone6a−10 to −5 °F
Coldest night−23.3 to −20.6 °C
Last frostApr 23
First frostOct 20
2012 zone6a

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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Clarks Summit, 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 Clarks Summit, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 23median — 50% chance of a later frost
Safe for tender plantsMay 10only 10% chance of frost after
First fall frostOctober 20median — 10% chance by Oct 4
Growing season178 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 10 and returns around November 3.

From the NOAA station Wilkes-Barre Intl Airport, PA — 9 miles away, elevation 932 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 18411

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 12 – Mar 26
SpinachSow outdoors · Mar 12 – Apr 2
Broccoli, cabbageStart indoors · Feb 12 – Feb 26
Broccoli, cabbageTransplant · Apr 2 – Apr 16
Onion setsPlant outdoors · Mar 26 – Apr 9
PotatoesPlant outdoors · Apr 2 – Apr 16
LettuceSow outdoors · Mar 26 – Apr 9
Carrots, beetsSow outdoors · Apr 2 – Apr 16
TomatoesStart indoors · Feb 26 – Mar 12
TomatoesTransplant · Apr 30 – May 14
Peppers, eggplantStart indoors · Feb 12 – Feb 26
Peppers, eggplantTransplant · May 7 – May 21
BeansSow outdoors · Apr 30 – May 14
Sweet cornSow outdoors · Apr 30 – May 14
Cucumbers, squashSow outdoors · Apr 30 – May 14
Fall lettuce, spinachSow outdoors · Aug 25 – Sep 8
GarlicPlant cloves · Oct 6 – Nov 10
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 23) and first fall frost (Oct 20) 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 18411 came on Apr 3 — 8 days earlier than the 1991–2020 average (Apr 11).

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 6a in Pennsylvania

598 plants native to the lower 48 states, recorded in Pennsylvania, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. 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 121

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 207

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 170

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBailey's sedge2.1 ft · blooms late spring · low shade tolerance · to −33 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 9

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 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °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 Clarks Summit, PA.

Soil in Clarks Summit, PA

The soil mapped at the center of ZIP 18411 is Oquaga — moderately decomposed plant material, well drained.

TextureModerately decomposed plant materialtop layer
pH4.8strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter80%high
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Oquaga and Lordstown channery loams, 25 to 70 percent slopes, rubbly.

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 18411; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Clarks Summit, PA

Summer high85 °Faverage high, July
Winter low20 °Faverage low, January
Hot days12days a year at 90 °F or more
Freezing nights122nights a year at 32 °F or less
Growing degree days3,103base 50 °F — the season’s usable heat
Longest day15 h 11 mindaylight on June 21
Shortest day9 h 10 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation38.7 inper year, rain and melted snow
Snowfall45 inper year

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 36 °F, low 20 °F 36°20° JanFebruary: average high 39 °F, low 22 °F 39°22° FebMarch: average high 48 °F, low 29 °F 48°29° MarApril: average high 61 °F, low 39 °F 61°39° AprMay: average high 72 °F, low 50 °F 72°50° 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 75 °F, low 54 °F 75°54° SepOctober: average high 63 °F, low 43 °F 63°43° OctNovember: average high 51 °F, low 34 °F 51°34° NovDecember: average high 40 °F, low 26 °F 40°26° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 2.59 in precipitation, 11.7 in snowfall 2.6❄12 JanFebruary: 2.07 in precipitation, 10.9 in snowfall 2.1❄11 FebMarch: 2.77 in precipitation, 10.1 in snowfall 2.8❄10 MarApril: 3.26 in precipitation, 0.8 in snowfall 3.3❄1 AprMay: 3.26 in precipitation 3.3 MayJune: 3.80 in precipitation 3.8 JunJuly: 3.61 in precipitation 3.6 JulAugust: 3.85 in precipitation 3.9 AugSeptember: 4.15 in precipitation 4.2 SepOctober: 3.71 in precipitation, 0.7 in snowfall 3.7❄1 OctNovember: 2.85 in precipitation, 3.2 in snowfall 2.9❄3 NovDecember: 2.80 in precipitation, 7.7 in snowfall 2.8❄8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Wilkes-Barre Intl Airport, PA (9 mi away); precipitation: Wilkes-Barre Intl Airport, PA (9 mi away). 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.

185046b
Scranton, PA · 3 mi
184106a
Chinchilla, PA · 3 mi
185156b
Scranton, PA · 4 mi
185086b
Scranton, PA · 5 mi
185176b
Taylor, PA · 5 mi
185036b
Scranton, PA · 5 mi
184716a
Waverly, PA · 5 mi
185026b
Scranton, PA · 5 mi

Pennsylvania planting zones →

Questions about 18411

What planting zone is ZIP code 18411?

ZIP code 18411 (Clarks Summit, PA) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Clarks Summit, PA?

The median last spring frost (32 °F) near 18411 is April 23; after May 10 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Wilkes-Barre Intl Airport station.

When is the first frost in Clarks Summit, PA?

The median first fall frost near 18411 is October 20, giving a median frost-free growing season of 178 days.

When should I plant tomatoes in 18411?

Start tomato seeds indoors around Feb 26 – Mar 12 and set transplants outside around Apr 30 – May 14, one to three weeks after the median last frost.

How much rain and snow does 18411 get?

About 38.7 inches of precipitation a year and 45 inches of snowfall (NOAA 1991–2020 normals, Wilkes-Barre Intl Airport station).

How hot do summers get in Clarks Summit, PA?

The average high peaks at 85 °F in July, with about 12 days a year at 90 °F or more.

What kind of soil does 18411 have?

The USDA soil survey maps Oquaga at the center of ZIP 18411: moderately decomposed plant material, well drained, pH about 4.8 (strongly acidic).

Did spring come early in Clarks Summit, PA in 2026?

Spring leaf-out near 18411 came on Apr 3 in 2026, 8 days earlier than the 1991–2020 average (Apr 11), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Clarks Summit, PA?

Long-day onions: the longest day near 18411 is 15 h 11 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).