Delaware County, in Pennsylvania, sits in USDA hardiness zone 7b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Among the crops suited to this profile: cabbage, prickly pear, california poppy, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Delaware County lies within Greater Philadelphia — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Delaware County holds more than one microclimate.
Soils and elevations shift across Delaware County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Delaware County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Delaware County — the short answer
Delaware County, Pennsylvania: USDA zone 7b, about 239 days between hard freezes, across 118K acres.
- USDA zone
- 7b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 24
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 18
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~239
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 118K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 7b is Delaware County's average, not your lot's — a low corner or a tree line moves it. Against Delaware County's 239-day season, see what your own ground reads.
Heat in Delaware County
Across a year, Delaware County accumulates about 3,556 growing degree days above 50°F, about 1,009 more than the middle Pennsylvania county — ahead of 65 of Pennsylvania’s 67 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Delaware County
Across Delaware County, the ground is predominantly Ultisols, where Glenelg, Manor, and Glenville are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 5.4–6.3, moderately acidic. Rainfall drains through hydrologic group C soils.
Soil order
Ultisols
Drainage
Well drained
Prime farmland
28%
Hydric soils
7%
Soil still varies lot by lot — soil types explained.
How the ground varies across Delaware County
The USDA soil survey maps 68% of Delaware County as well drained — but another 28% drains differently: 20% moderately well drained, 5% poorly drained.
Glenelg is the most extensive named soil at 25% of mapped acres, then Manor (9%) and Glenville (9%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Delaware County
Each reading below is measured for Delaware County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Delaware County are well drained, in hydrologic group C — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Delaware County runs about pH 5.4–6.3, on the acidic side.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Season length
MeasuredDelaware County runs about 239 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredDelaware County sits in USDA hardiness zone 7b.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Delaware County is in
Delaware County spans 2 EPA Level III ecoregions — Northern Piedmont (86%) and Middle Atlantic Coastal Plain (14%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in Delaware County
We scored all 1,086 plants against Delaware County's own USDA zone 7b and its own 239-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Pennsylvania profile.
Is it too late to plant in Delaware County?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Feb 24; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 24 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 18 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
Documented around Delaware County
Spotted lanternfly documented 1 miles from Delaware County, first recorded 2017. What to watch for.
- Japanese beetle14 documented records
- monarch butterfly185 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Delaware County
USGS estimates 176 lb of Chlorpyrifos on Delaware County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (137 lb) and Metolachlor-s (135 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Delaware County — and how to grow with it.
We checked the federal record across Delaware County — 1,708 documented sites across 7 of the 9 source types we track.
The most significant on record: 18 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Delaware County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Delaware County
Closest first, across Delaware County. Listing isn't leaking, and distance isn't exposure.
- MIKE WHITES AUTO BODY/MEDIABrownfields · 200 ft
- CHESTER MATERIALSUnderground Storage Tanks · 200 ft
- EXXON RAS NO 21197Brownfields · 250 ft
- CHEMICAL COATINGS & ENGINEERINGBrownfields · 250 ft
- CONCORD AUTO BODY OF MEDIABrownfields · 300 ft
- SUBURBAN MOTORSBrownfields · 300 ft
- VOLPES AUTO BODY/MEDIABrownfields · 350 ft
- MEDIA AUTO SERVICE INCBrownfields · 400 ft
- EXXON RS 2 1197Underground Storage Tanks · 450 ft
- EXXON RS 2 1304Underground Storage Tanks · 700 ft
- MARTIN J COSENZA EXXONUnderground Storage Tanks · 750 ft
- D SABATELLIUnderground Storage Tanks · 1100 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Delaware County's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Delaware County.
Sources Checked
across Delaware County
Severity Distribution
across Delaware County
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Check your specific parcel in Delaware County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Delaware County average
Your land is one point inside Delaware County
Everything above resolves to Delaware County as a whole — one PHZM band and one county frost record, read across 118K acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at county scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better county average.
Your Lot vs the Delaware County Average
Delaware County Average
- ●USDA Zones 7b, averaged across Delaware County
- ●One soil character for all of Delaware County
- ●Frost dates read at Delaware County's scale: Mar 24 to Nov 18
YOUR Parcel
- ✓Your exact zone, not Delaware County's 7b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Delaware County
Pull a site-specific report for your exact address in Delaware County, Pennsylvania — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Delaware County averages can't show:
We read public map data around Delaware County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Delaware County average
How we know this about Delaware County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Delaware County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Delaware County
When does frost risk typically end in Delaware County?
The last hard freeze (28°F) in Delaware County typically lands around Mar 24, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Apr 14.
How long is the growing season in Delaware County?
Measured between 28°F hard freezes, Delaware County sees about 239 frost-free days — roughly Mar 24 through Nov 18, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 14 to Nov 4, about 204 days.
Is the soil safe to grow vegetables in Delaware County?
The federal record around Delaware County runs heavier than most — 1,708 documented sites, mostly Underground Storage Tanks entries (872), the nearest Brownfields record under a tenth of a mile out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
Everything above is measured at Delaware County's scale — its 7b band and its 239-day season. Your yard writes its own version of Delaware County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Pennsylvania's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Delaware County’s own scale
9 of the readings below were taken at Delaware County's own scale — its own ~239-day span between 28°F freezes, the 3 most extensive soil series mapped here and 1,708 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Delaware County's own USDA hardiness band, zones 7bUSDA PHZM 2023
- Delaware County's own 28°F hard-freeze dates and its ~239-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Delaware CountyUSDA NRCS SSURGO
- 1,708 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Brownfields record under a tenth of a mile outFederal environmental registers
- Delaware County's boundary and the 117,637 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7b and a ~239-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Delaware County spans, Northern Piedmont the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Delaware County for 2 tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Delaware County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Pennsylvania grower plans around — written at state scale, so they stay on the state guidefrom Pennsylvania
What this page can’t tell you
- How the season shifts across Delaware County — the ~239 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Delaware County's 117,637 acreswhy one lot differs from the next →
- Which of those 1,708 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Delaware Countyread your own land →