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

Planting zone for 16928 — Knoxville, PA

ZIP code 16928 (Knoxville, Tioga County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 9 and the first fall frost October 12.

Where ZIP 16928 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.

Zone5b−15 to −10 °F
Coldest night−26.1 to −23.3 °C
Last frostMay 9
First frostOct 12
2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Knoxville, 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 Knoxville, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 9median — 50% chance of a later frost
Safe for tender plantsMay 25only 10% chance of frost after
First fall frostOctober 12median — 10% chance by Sep 29
Growing season155 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 29 and returns around October 26.

From the NOAA station Cowanesque Dam, PA — 14 miles away, elevation 1,152 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 16928

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 28 – Apr 11
SpinachSow outdoors · Mar 28 – Apr 18
Broccoli, cabbageStart indoors · Feb 28 – Mar 14
Broccoli, cabbageTransplant · Apr 18 – May 2
Onion setsPlant outdoors · Apr 11 – Apr 25
PotatoesPlant outdoors · Apr 18 – May 2
LettuceSow outdoors · Apr 11 – Apr 25
Carrots, beetsSow outdoors · Apr 18 – May 2
TomatoesStart indoors · Mar 14 – Mar 28
TomatoesTransplant · May 16 – May 30
Peppers, eggplantStart indoors · Feb 28 – Mar 14
Peppers, eggplantTransplant · May 23 – Jun 6
BeansSow outdoors · May 16 – May 30
Sweet cornSow outdoors · May 16 – May 30
Cucumbers, squashSow outdoors · May 16 – May 30
Fall lettuce, spinachSow outdoors · Aug 17 – Aug 31
GarlicPlant cloves · Sep 28 – Nov 2
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 9) and first fall frost (Oct 12) 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 16928 came on Apr 6 — 8 days earlier than the 1991–2020 average (Apr 14).

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 5b in Pennsylvania

572 plants native to the lower 48 states, recorded in Pennsylvania, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Trees 75

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 113

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 198

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 166

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 8

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 honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °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 Knoxville, PA.

Soil in Knoxville, PA

The soil mapped at the center of ZIP 16928 is Philo — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables
pH5.3strongly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter3%moderate
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Philo silt loam.

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 16928; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Knoxville, PA

Summer high81 °Faverage high, July
Winter low15 °Faverage low, January
Hot days8days a year at 90 °F or more
Freezing nights161nights a year at 32 °F or less
Growing degree days2,365base 50 °F — the season’s usable heat
Longest day15 h 14 mindaylight on June 21
Shortest day9 h 07 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation37.6 inper year, rain and melted snow
Snowfall49 inper year; 75 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 32 °F, low 15 °F 32°15° JanFebruary: average high 35 °F, low 15 °F 35°15° FebMarch: average high 44 °F, low 22 °F 44°22° MarApril: average high 57 °F, low 33 °F 57°33° AprMay: average high 69 °F, low 44 °F 69°44° MayJune: average high 77 °F, low 53 °F 77°53° JunJuly: average high 81 °F, low 58 °F 81°58° JulAugust: average high 80 °F, low 57 °F 80°57° AugSeptember: average high 73 °F, low 50 °F 73°50° SepOctober: average high 61 °F, low 39 °F 61°39° OctNovember: average high 48 °F, low 30 °F 48°30° NovDecember: average high 37 °F, low 22 °F 37°22° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″January: 2.60 in precipitation, 10.6 in snowfall 2.6❄11 JanFebruary: 1.96 in precipitation, 10.5 in snowfall 2.0❄11 FebMarch: 2.88 in precipitation, 10.6 in snowfall 2.9❄11 MarApril: 3.03 in precipitation, 2.4 in snowfall 3.0❄2 AprMay: 3.33 in precipitation 3.3 MayJune: 3.44 in precipitation 3.4 JunJuly: 3.71 in precipitation 3.7 JulAugust: 3.68 in precipitation 3.7 AugSeptember: 3.75 in precipitation 3.8 SepOctober: 3.60 in precipitation, 0.6 in snowfall 3.6❄1 OctNovember: 2.74 in precipitation, 3.3 in snowfall 2.7❄3 NovDecember: 2.88 in precipitation, 10.7 in snowfall 2.9❄11 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Cowanesque Dam, PA (14 mi away); precipitation: Sabinsville 3 Se, PA (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

169425b
Osceola, PA · 4 mi
169506a
Westfield, PA · 7 mi
148985b
Woodhull, NY · 7 mi
169356a
Middlebury Center, PA · 8 mi
169205b
Elkland, PA · 8 mi
148856a
Troupsburg, NY · 10 mi
169275b
Harrison Valley, PA · 12 mi
169435b
Sabinsville, PA · 12 mi

Pennsylvania planting zones →

Questions about 16928

What planting zone is ZIP code 16928?

ZIP code 16928 (Knoxville, PA) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Knoxville, PA?

The median last spring frost (32 °F) near 16928 is May 9; after May 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Cowanesque Dam station.

When is the first frost in Knoxville, PA?

The median first fall frost near 16928 is October 12, giving a median frost-free growing season of 155 days.

When should I plant tomatoes in 16928?

Start tomato seeds indoors around Mar 14 – Mar 28 and set transplants outside around May 16 – May 30, one to three weeks after the median last frost.

How much rain and snow does 16928 get?

About 37.6 inches of precipitation a year and 49 inches of snowfall (NOAA 1991–2020 normals, Sabinsville 3 Se station).

How hot do summers get in Knoxville, PA?

The average high peaks at 81 °F in July, with about 8 days a year at 90 °F or more.

What kind of soil does 16928 have?

The USDA soil survey maps Philo at the center of ZIP 16928: silt loam, moderately well drained, pH about 5.3 (strongly acidic).

Did spring come early in Knoxville, PA in 2026?

Spring leaf-out near 16928 came on Apr 6 in 2026, 8 days earlier than the 1991–2020 average (Apr 14), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Knoxville, PA?

Long-day onions: the longest day near 16928 is 15 h 14 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).