Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 19333 — Devon, PA

ZIP code 19333 (Devon, Chester County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 8 and the first fall frost October 31.

Where ZIP 19333 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 8

First frostOct 31

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 Devon, 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 Devon, PA

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostApril 8median — 50% chance of a later frost

Safe for tender plantsApril 23only 10% chance of frost after

First fall frostOctober 31median — 10% chance by Oct 14

Growing season203 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 31 and returns around November 10.

From the NOAA station Norristown, PA — 7 miles away, elevation 62 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 19333

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 25 – Mar 11

SpinachSow outdoors · Feb 25 – Mar 18

Broccoli, cabbageStart indoors · Jan 28 – Feb 11

Broccoli, cabbageTransplant · Mar 18 – Apr 1

Onion setsPlant outdoors · Mar 11 – Mar 25

PotatoesPlant outdoors · Mar 18 – Apr 1

LettuceSow outdoors · Mar 11 – Mar 25

Carrots, beetsSow outdoors · Mar 18 – Apr 1

TomatoesStart indoors · Feb 11 – Feb 25

TomatoesTransplant · Apr 15 – Apr 29

Peppers, eggplantStart indoors · Jan 28 – Feb 11

Peppers, eggplantTransplant · Apr 22 – May 6

BeansSow outdoors · Apr 15 – Apr 29

Sweet cornSow outdoors · Apr 15 – Apr 29

Cucumbers, squashSow outdoors · Apr 15 – Apr 29

Fall lettuce, spinachSow outdoors · Sep 5 – Sep 19

GarlicPlant cloves · Oct 17 – Nov 21

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 8) and first fall frost (Oct 31) 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 19333 came on Mar 22 — 5 days earlier than the 1991–2020 average (Mar 27).

average
Mar 272026
Mar 22

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.

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 Devon, PA.

Soil in Devon, PA

The soil mapped at the center of ZIP 19333 is Gladstone — gravelly loam, well drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureGravelly loama good balance for most vegetables

pH6.1slightly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Urban land-Gladstone complex, 0 to 8 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 19333; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Devon, PA

Summer high89 °Faverage high, July

Winter low23 °Faverage low, January

Hot days39days a year at 90 °F or more

Freezing nights107nights a year at 32 °F or less

Growing degree days3,815base 50 °F — the season’s usable heat

Longest day15 h 01 mindaylight on June 21

Shortest day9 h 19 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation48.4 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Norristown, PA (7 mi away); precipitation: Villanova, PA (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

Valley Forge, PA · 3 mi

194817a

Valley Forge, PA · 4 mi

190857a

Villanova, PA · 4 mi

190737a

Newtown Square, PA · 4 mi

194067a

King Of Prussia, PA · 4 mi

Pennsylvania planting zones →

Questions about 19333

What planting zone is ZIP code 19333?

ZIP code 19333 (Devon, 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 Devon, PA?

The median last spring frost (32 °F) near 19333 is April 8; after April 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Norristown station.

When is the first frost in Devon, PA?

The median first fall frost near 19333 is October 31, giving a median frost-free growing season of 203 days.

When should I plant tomatoes in 19333?

Start tomato seeds indoors around Feb 11 – Feb 25 and set transplants outside around Apr 15 – Apr 29, one to three weeks after the median last frost.

How much rain and snow does 19333 get?

About 48.4 inches of precipitation a year (NOAA 1991–2020 normals, Villanova station).

How hot do summers get in Devon, PA?

The average high peaks at 89 °F in July, with about 39 days a year at 90 °F or more.

What kind of soil does 19333 have?

The USDA soil survey maps Gladstone at the center of ZIP 19333: gravelly loam, well drained, pH about 6.1 (slightly acidic).

Did spring come early in Devon, PA in 2026?

Spring leaf-out near 19333 came on Mar 22 in 2026, 5 days earlier than the 1991–2020 average (Mar 27), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Devon, PA?

Long-day onions: the longest day near 19333 is 15 h 01 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).