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

Planting zone for 17978 — Spring Glen, PA

ZIP code 17978 (Spring Glen, Schuylkill County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 1 and the first fall frost October 16.

Where ZIP 17978 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 frostMay 1
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 Spring Glen, 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 Spring Glen, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 1median — 50% chance of a later frost
Safe for tender plantsMay 20only 10% chance of frost after
First fall frostOctober 16median — 10% chance by Oct 3
Growing season168 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 18 and returns around October 30.

From the NOAA station Dehart Dam, PA — 12 miles away, elevation 538 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 17978

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 20 – Apr 3
SpinachSow outdoors · Mar 20 – Apr 10
Broccoli, cabbageStart indoors · Feb 20 – Mar 6
Broccoli, cabbageTransplant · Apr 10 – Apr 24
Onion setsPlant outdoors · Apr 3 – Apr 17
PotatoesPlant outdoors · Apr 10 – Apr 24
LettuceSow outdoors · Apr 3 – Apr 17
Carrots, beetsSow outdoors · Apr 10 – Apr 24
TomatoesStart indoors · Mar 6 – Mar 20
TomatoesTransplant · May 8 – May 22
Peppers, eggplantStart indoors · Feb 20 – Mar 6
Peppers, eggplantTransplant · May 15 – May 29
BeansSow outdoors · May 8 – May 22
Sweet cornSow outdoors · May 8 – May 22
Cucumbers, squashSow outdoors · May 8 – May 22
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 (May 1) 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 17978 came on Mar 31 — 5 days earlier than the 1991–2020 average (Apr 5).

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 Spring Glen, PA.

Soil in Spring Glen, PA

The soil mapped at the center of ZIP 17978 is Calvin — channery silt loam, well drained.

TextureChannery silt loama good balance for most vegetables
pH5.8moderately acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupBwater soaks in moderately
Farmland classprime farmlandUSDA classification

Map unit: Calvin-Leck Kill shaly silt loams, 3 to 8 percent slopes, moderately 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 17978; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Spring Glen, PA

Summer high84 °Faverage high, July
Winter low20 °Faverage low, January
Hot days14days a year at 90 °F or more
Freezing nights128nights a year at 32 °F or less
Growing degree days2,845base 50 °F — the season’s usable heat
Longest day15 h 05 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)
Precipitation50.9 inper year, rain and melted snow
Snowfall28 inper year; 36 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 37 °F, low 20 °F 37°20° JanFebruary: average high 40 °F, low 21 °F 40°21° FebMarch: average high 49 °F, low 28 °F 49°28° MarApril: average high 61 °F, low 37 °F 61°37° AprMay: average high 71 °F, low 47 °F 71°47° MayJune: average high 79 °F, low 56 °F 79°56° JunJuly: average high 84 °F, low 60 °F 84°60° JulAugust: average high 82 °F, low 59 °F 82°59° AugSeptember: average high 75 °F, low 52 °F 75°52° SepOctober: average high 64 °F, low 41 °F 64°41° OctNovember: average high 52 °F, low 32 °F 52°32° NovDecember: average high 42 °F, low 25 °F 42°25° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 3.59 in precipitation, 8.4 in snowfall 3.6❄8 JanFebruary: 2.83 in precipitation, 8.3 in snowfall 2.8❄8 FebMarch: 3.88 in precipitation, 5.1 in snowfall 3.9❄5 MarApril: 4.46 in precipitation, 0.6 in snowfall 4.5❄1 AprMay: 4.42 in precipitation 4.4 MayJune: 4.87 in precipitation 4.9 JunJuly: 5.05 in precipitation 5.0 JulAugust: 4.27 in precipitation 4.3 AugSeptember: 5.63 in precipitation 5.6 SepOctober: 4.54 in precipitation 4.5 OctNovember: 3.30 in precipitation, 0.8 in snowfall 3.3❄1 NovDecember: 4.01 in precipitation, 4.4 in snowfall 4.0❄4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Dehart Dam, PA (12 mi away); precipitation: Dehart Dam, PA (12 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

170986b
Williamstown, PA · 2 mi
179686b
Sacramento, PA · 2 mi
170486b
Lykens, PA · 3 mi
170976b
Wiconisco, PA · 3 mi
170306b
Gratz, PA · 5 mi
179416b
Klingerstown, PA · 5 mi
179836b
Valley View, PA · 6 mi
179806b
Tower City, PA · 7 mi

Pennsylvania planting zones →

Questions about 17978

What planting zone is ZIP code 17978?

ZIP code 17978 (Spring Glen, 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 Spring Glen, PA?

The median last spring frost (32 °F) near 17978 is May 1; after May 20 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Dehart Dam station.

When is the first frost in Spring Glen, PA?

The median first fall frost near 17978 is October 16, giving a median frost-free growing season of 168 days.

When should I plant tomatoes in 17978?

Start tomato seeds indoors around Mar 6 – Mar 20 and set transplants outside around May 8 – May 22, one to three weeks after the median last frost.

How much rain and snow does 17978 get?

About 50.9 inches of precipitation a year and 28 inches of snowfall (NOAA 1991–2020 normals, Dehart Dam station).

How hot do summers get in Spring Glen, PA?

The average high peaks at 84 °F in July, with about 14 days a year at 90 °F or more.

What kind of soil does 17978 have?

The USDA soil survey maps Calvin at the center of ZIP 17978: channery silt loam, well drained, pH about 5.8 (moderately acidic).

Did spring come early in Spring Glen, PA in 2026?

Spring leaf-out near 17978 came on Mar 31 in 2026, 5 days earlier than the 1991–2020 average (Apr 5), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Spring Glen, PA?

Long-day onions: the longest day near 17978 is 15 h 05 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).