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

Planting zone for 17551 — Millersville, PA

ZIP code 17551 (Millersville, Lancaster County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 1 and the first fall frost November 10.

Where ZIP 17551 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.

Zone7a0 to 5 °F
Coldest night−17.8 to −15 °C
Last frostApr 1
First frostNov 10
2012 zone6b

Was 6b on the 2012 map — half a zone warmer now. 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 Millersville, 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 Millersville, PA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 1median — 50% chance of a later frost
Safe for tender plantsApril 13only 10% chance of frost after
First fall frostNovember 10median — 10% chance by Oct 28
Growing season221 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 22 and returns around November 22.

From the NOAA station Safe Harbor Dam, PA — 4 miles away, elevation 194 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 17551

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 18 – Mar 4
SpinachSow outdoors · Feb 18 – Mar 11
Broccoli, cabbageStart indoors · Jan 21 – Feb 4
Broccoli, cabbageTransplant · Mar 11 – Mar 25
Onion setsPlant outdoors · Mar 4 – Mar 18
PotatoesPlant outdoors · Mar 11 – Mar 25
LettuceSow outdoors · Mar 4 – Mar 18
Carrots, beetsSow outdoors · Mar 11 – Mar 25
TomatoesStart indoors · Feb 4 – Feb 18
TomatoesTransplant · Apr 8 – Apr 22
Peppers, eggplantStart indoors · Jan 21 – Feb 4
Peppers, eggplantTransplant · Apr 15 – Apr 29
BeansSow outdoors · Apr 8 – Apr 22
Sweet cornSow outdoors · Apr 8 – Apr 22
Cucumbers, squashSow outdoors · Apr 8 – Apr 22
Fall lettuce, spinachSow outdoors · Sep 15 – Sep 29
GarlicPlant cloves · Oct 27 – Dec 1
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 1) and first fall frost (Nov 10) 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 17551 came on Mar 21 — 4 days earlier than the 1991–2020 average (Mar 25).

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 Millersville, PA.

Soil in Millersville, PA

The soil mapped at the center of ZIP 17551 is Letort — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH5.9moderately acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupBwater soaks in moderately
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Letort silt loam, 8 to 15 percent slopes.

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 17551; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Millersville, PA

Summer high87 °Faverage high, July
Winter low25 °Faverage low, January
Hot days20days a year at 90 °F or more
Freezing nights87nights a year at 32 °F or less
Growing degree days3,703base 50 °F — the season’s usable heat
Longest day15 h 01 mindaylight on June 21
Shortest day9 h 20 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation46.3 inper year, rain and melted snow
Snowfall21 inper year; 21 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 39 °F, low 25 °F 39°25° JanFebruary: average high 41 °F, low 26 °F 41°26° FebMarch: average high 50 °F, low 33 °F 50°33° MarApril: average high 63 °F, low 44 °F 63°44° AprMay: average high 72 °F, low 53 °F 72°53° MayJune: average high 82 °F, low 63 °F 82°63° JunJuly: average high 87 °F, low 68 °F 87°68° JulAugust: average high 84 °F, low 66 °F 84°66° AugSeptember: average high 77 °F, low 60 °F 77°60° SepOctober: average high 65 °F, low 48 °F 65°48° OctNovember: average high 53 °F, low 38 °F 53°38° NovDecember: average high 44 °F, low 30 °F 44°30° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 3.26 in precipitation, 6.1 in snowfall 3.3❄6 JanFebruary: 2.68 in precipitation, 7.6 in snowfall 2.7❄8 FebMarch: 4.05 in precipitation, 3.5 in snowfall 4.0❄4 MarApril: 3.54 in precipitation 3.5 AprMay: 3.88 in precipitation 3.9 MayJune: 4.55 in precipitation 4.5 JunJuly: 4.31 in precipitation 4.3 JulAugust: 3.57 in precipitation 3.6 AugSeptember: 4.88 in precipitation 4.9 SepOctober: 4.37 in precipitation 4.4 OctNovember: 3.40 in precipitation, 0.5 in snowfall 3.4❄1 NovDecember: 3.82 in precipitation, 3.6 in snowfall 3.8❄4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Safe Harbor Dam, PA (4 mi away); precipitation: Safe Harbor Dam, PA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

175167a
Conestoga, PA · 4 mi
175047a
Bausman, PA · 4 mi
176037a
Lancaster, PA · 4 mi
175827a
Washington Boro, PA · 4 mi
175037a
Bart, PA · 5 mi
175647a
Penryn, PA · 5 mi
176057a
Lancaster, PA · 5 mi
176077a
Lancaster, PA · 5 mi

Pennsylvania planting zones →

Questions about 17551

What planting zone is ZIP code 17551?

ZIP code 17551 (Millersville, 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 Millersville, PA?

The median last spring frost (32 °F) near 17551 is April 1; after April 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Safe Harbor Dam station.

When is the first frost in Millersville, PA?

The median first fall frost near 17551 is November 10, giving a median frost-free growing season of 221 days.

When should I plant tomatoes in 17551?

Start tomato seeds indoors around Feb 4 – Feb 18 and set transplants outside around Apr 8 – Apr 22, one to three weeks after the median last frost.

How much rain and snow does 17551 get?

About 46.3 inches of precipitation a year and 21 inches of snowfall (NOAA 1991–2020 normals, Safe Harbor Dam station).

How hot do summers get in Millersville, PA?

The average high peaks at 87 °F in July, with about 20 days a year at 90 °F or more.

What kind of soil does 17551 have?

The USDA soil survey maps Letort at the center of ZIP 17551: silt loam, well drained, pH about 5.9 (moderately acidic).

Did spring come early in Millersville, PA in 2026?

Spring leaf-out near 17551 came on Mar 21 in 2026, 4 days earlier than the 1991–2020 average (Mar 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Millersville, PA?

Long-day onions: the longest day near 17551 is 15 h 01 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 17551 change?

Yes. The 2012 USDA map put 17551 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.