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

Planting zone for 17128 — Harrisburg, PA

ZIP code 17128 (Harrisburg, Dauphin County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 15 and the first fall frost October 23.

Where ZIP 17128 is

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 15
First frostOct 23
2012 zone7a

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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Harrisburg, 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 Harrisburg, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 15median — 50% chance of a later frost
Safe for tender plantsMay 2only 10% chance of frost after
First fall frostOctober 23median — 10% chance by Oct 7
Growing season189 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 3 and returns around November 5.

From the NOAA station Harrisburg 1 Ne, PA — within 1 mile, elevation 420 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 17128

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 4 – Mar 18
SpinachSow outdoors · Mar 4 – Mar 25
Broccoli, cabbageStart indoors · Feb 4 – Feb 18
Broccoli, cabbageTransplant · Mar 25 – Apr 8
Onion setsPlant outdoors · Mar 18 – Apr 1
PotatoesPlant outdoors · Mar 25 – Apr 8
LettuceSow outdoors · Mar 18 – Apr 1
Carrots, beetsSow outdoors · Mar 25 – Apr 8
TomatoesStart indoors · Feb 18 – Mar 4
TomatoesTransplant · Apr 22 – May 6
Peppers, eggplantStart indoors · Feb 4 – Feb 18
Peppers, eggplantTransplant · Apr 29 – May 13
BeansSow outdoors · Apr 22 – May 6
Sweet cornSow outdoors · Apr 22 – May 6
Cucumbers, squashSow outdoors · Apr 22 – May 6
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 15) 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 17128 came on Mar 21 — 8 days earlier than the 1991–2020 average (Mar 29).

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 Pennsylvania

620 plants native to the lower 48 states, recorded in Pennsylvania, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. Each links to its USDA PLANTS profile.

Trees 78

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 123

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 212

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 181

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 11

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °FAmerican wisteria50 ft · blooms spring · low shade tolerance · to −3 °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 °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 Harrisburg, PA.

Soil in Harrisburg, PA

The soil mapped at the center of ZIP 17128 is Tioga — fine sandy loam, well drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding
pH5.5moderately acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.75%low — add compost
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Urban land, alluvial materials.

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 17128; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Harrisburg, PA

Summer high85 °Faverage high, July
Winter low22 °Faverage low, January
Hot days18days a year at 90 °F or more
Freezing nights111nights a year at 32 °F or less
Growing degree days3,209base 50 °F — the season’s usable heat
Longest day15 h 03 mindaylight on June 21
Shortest day9 h 18 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation45.2 inper year, rain and melted snow
Snowfall24 inper year; 31 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 37 °F, low 22 °F 37°22° JanFebruary: average high 40 °F, low 23 °F 40°23° FebMarch: average high 48 °F, low 30 °F 48°30° MarApril: average high 61 °F, low 40 °F 61°40° AprMay: average high 72 °F, low 51 °F 72°51° MayJune: average high 81 °F, low 60 °F 81°60° JunJuly: average high 85 °F, low 65 °F 85°65° JulAugust: average high 83 °F, low 62 °F 83°62° AugSeptember: average high 75 °F, low 55 °F 75°55° SepOctober: average high 63 °F, low 43 °F 63°43° OctNovember: average high 51 °F, low 34 °F 51°34° NovDecember: average high 41 °F, low 27 °F 41°27° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 2.87 in precipitation, 6.4 in snowfall 2.9❄6 JanFebruary: 2.77 in precipitation, 7.7 in snowfall 2.8❄8 FebMarch: 3.93 in precipitation, 4.5 in snowfall 3.9❄5 MarApril: 3.91 in precipitation, 0.4 in snowfall 3.9 AprMay: 4.02 in precipitation 4.0 MayJune: 4.00 in precipitation 4.0 JunJuly: 4.81 in precipitation 4.8 JulAugust: 4.28 in precipitation 4.3 AugSeptember: 4.58 in precipitation 4.6 SepOctober: 3.77 in precipitation 3.8 OctNovember: 2.87 in precipitation, 0.7 in snowfall 2.9❄1 NovDecember: 3.42 in precipitation, 4.2 in snowfall 3.4❄4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Harrisburg 1 Ne, PA (within 1 mile); precipitation: Harrisburg 1 Ne, PA (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

171307a
Harrisburg, PA · <1 mi
171237a
Harrisburg, PA · <1 mi
171247a
Harrisburg, PA · <1 mi
171257a
Harrisburg, PA · <1 mi
171057a
Harrisburg, PA · <1 mi
171207a
Harrisburg, PA · <1 mi
171267a
Harrisburg, PA · <1 mi
171277a
Harrisburg, PA · <1 mi

All 26 ZIP codes in Harrisburg → · Pennsylvania planting zones →

Questions about 17128

What planting zone is ZIP code 17128?

ZIP code 17128 (Harrisburg, PA) 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 Harrisburg, PA?

The median last spring frost (32 °F) near 17128 is April 15; after May 2 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Harrisburg 1 Ne station.

When is the first frost in Harrisburg, PA?

The median first fall frost near 17128 is October 23, giving a median frost-free growing season of 189 days.

When should I plant tomatoes in 17128?

Start tomato seeds indoors around Feb 18 – Mar 4 and set transplants outside around Apr 22 – May 6, one to three weeks after the median last frost.

How much rain and snow does 17128 get?

About 45.2 inches of precipitation a year and 24 inches of snowfall (NOAA 1991–2020 normals, Harrisburg 1 Ne station).

How hot do summers get in Harrisburg, PA?

The average high peaks at 85 °F in July, with about 18 days a year at 90 °F or more.

What kind of soil does 17128 have?

The USDA soil survey maps Tioga at the center of ZIP 17128: fine sandy loam, well drained, pH about 5.5 (moderately acidic).

Did spring come early in Harrisburg, PA in 2026?

Spring leaf-out near 17128 came on Mar 21 in 2026, 8 days earlier than the 1991–2020 average (Mar 29), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Harrisburg, PA?

Long-day onions: the longest day near 17128 is 15 h 03 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).