Generally — Most Areas
California poppy (zones 6-10) suits most of Pennsylvania (5b-8a) — zones 6-8 are in range, and the rest of the state is the exception.
California Poppy in Pennsylvania — the short answer
California Poppy in Pennsylvania: hardy in zones 6–10, full sun, against a state median of ~197 frost-free days.
- Plant zones
- 6-10
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Pennsylvania zones
- 5b-8a
- USDA PHZM 2023
- Frost window
- Apr 6 - Apr 24 – Oct 25 - Nov 3
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 160 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 60 days
- Growable Ground Plant Database
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — per-field provenance varies and is published with the dataset.
Your yard isn't the whole zone.
Pennsylvania spans zones 5b-8a, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score california poppy against your parcel's actual hardiness, soil, and sun.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Pennsylvania is not one climate
Pennsylvania’s winter-low ladder runs across 67 counties, from zone 5.5 in Cambria County to zone 7.5 in Philadelphia County. That is 20°F between the two counties’ average coldest night — the difference between california poppy overwintering in the ground and coming under cover.
The middle half of 67 counties runs 6–7 zones, with a median of 6.5 zones — a 2-zone span end to end.
Measured across 67 Pennsylvania counties. USDA PHZM 2023, per county. Quartiles are order statistics — every figure shown is a value a real county recorded, not an interpolation. Your own site sits somewhere inside this range; a parcel report resolves where.
Where in Pennsylvania Fits Best
California Poppy is rated for zones 6–10 — a cold floor USDA puts at -10 to 0°F. Against Pennsylvania’s 67 counties that band holds in 60 of them, and the line runs at Bradford County (zone 6a), the coldest county still inside it.
Inside zones 6–10
60 counties
- Butler County · zone 6a
- Clarion County · zone 6a
- Clearfield County · zone 6a
3 of 60 shown
Below the zone 6 floor
7 counties
- Cambria County · zone 5b
- Cameron County · zone 5b
- Elk County · zone 5b
3 of 7 shown
Winter cold is the limit here — the same plant works in a container that comes under cover.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. A zone is a 10°F band of average annual extreme minimum temperature, so the floor above is the band the plant's rating denotes, not a single measured kill point. Slope, shelter and cold-air drainage routinely move a site half a zone either way from its county figure — which is the part only your address resolves.
Even within Pennsylvania's zones 5b-8a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for california poppy (USDA PHZM 2023):
Zone Comparison
California Poppy Needs
- USDA Zones: 6-10
- Frost-Free Days: 60+
- Sun: Full Sun
- Mature size: 1.5 ft tall
- Picking window: ~60 days of harvest
- Drought tolerance: High
Pennsylvania Has
- USDA Zones: 5b-8a
- Last Hard Freeze (28°F): Apr 6 - Apr 24
- First Hard Freeze (28°F): Oct 25 - Nov 3
- Annual Rainfall: 36-48 inches
- Common Soils: Silt loam, Shale-derived, Limestone-derived
Plant Zone Range (zones 6-10)
Preferred Soil pH
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant California Poppy in Pennsylvania
The frost window
Across Pennsylvania, the last spring hard freeze (28°F) clears between Apr 6 and Apr 24, and the first fall hard freeze lands between Oct 25 and Nov 3 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 184-day window you can count on — up to 211 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
When to start the seed
California Poppy is direct-sown where it grows rather than started under cover, so there is no seed-tray head start to bank — Pennsylvania's dates above are the whole calendar for it. That makes the last-freeze date the binding constraint, and a warmer pocket of your own yard is worth more to this crop than it is to a transplanted one.
Winter standing
Pennsylvania runs as cold as USDA zone 5, and no sourced winter-hardiness floor is on record for california poppy, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether california poppy is a permanent planting or a replant-every-spring crop for you turns on your own zone within Pennsylvania; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Potter County, not the statewide average.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
The zone check says california poppy survives winter in part of Pennsylvania, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
California Poppy wants 60+ frost-free days; a typical Pennsylvania site sees ~197 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
California Poppy needs ~800 GDD (base 50°F) to ripen. The state median runs ~2447 GDD (from PRISM 1991-2020 climate normals), so Pennsylvania's typical season clears that easily.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Soil + Drainage Fit
California Poppy tolerates a wide pH range (pH 5-8) — 3 units, acid ground through alkaline — so soil acidity is rarely what limits it in Pennsylvania. A soil test is still worth having, but for what else it tells you about this site, not to clear this plant. It will grow across that whole span, but it does best between pH 6 and 7.5 — worth knowing before you decide whether a Pennsylvania soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Pennsylvania site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
SSURGO maps about 14.1% of Pennsylvania as poorly or somewhat-poorly drained, and the class flips parcel to parcel. California Poppy tolerates drought well, so wet feet — not dry spells — is its real risk here — your soil map unit, not the state average, is the real answer.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Pennsylvania soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Before you plant california poppy for food
Anything you grow to eat takes up what is in the ground it grows in, so what is on record near you is worth knowing before california poppy goes in. What follows is Pennsylvania’s documented federal record at state scale — a screening signal, not a soil test, and not a statement about any one lot.
Safe to Grow Here?
What the federal record shows across Pennsylvania — and how to grow with it.
We checked the federal record across Pennsylvania — 68,671 documented sites across 8 of the 9 source types we track.
The most significant on record: 393 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Pennsylvania 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.
Severity Distribution
across Pennsylvania
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Pennsylvania, CAFO runs higher than the national average — 642 sites across Pennsylvania. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What Else to Consider for California Poppy in Pennsylvania
Zone compatibility tells you about winter cold survival — but Pennsylvania growers also need to think about:
Rocky shale soils in the ridge-and-valley region
Short mountain seasons in the Poconos and Alleghenies
Deer pressure is among the highest in the US
Growing california poppy here specifically
California Poppy likes pH 5.0–8.0 and its growing tissue burns around 14°F (FAO ECOCROP), yet neither saves it from wet feet — SSURGO maps about 14.1% of Pennsylvania poorly-drained, where its crown sit and rot.
Set california poppy high on bermed, grit-amended ground so winter and storm water drain away from the crown. How to handle it →
What to actually do about these — and the constraints that apply to every Pennsylvania grower, not just california poppy — is covered on the Pennsylvania growing guide.
Timing shifts within Pennsylvania
Pennsylvania isn't one climate. In Potter County, the last hard freeze (28°F) holds until about May 5 — roughly 21 days later than the recorded state median — so plant california poppy to your county's window, not the statewide date.
California Poppy needs about 60 days of frost-free season to complete its cycle. Even Potter County — Pennsylvania’s shortest season at 160 frost-free days — clears that by 100 days, so season length isn’t the constraint anywhere in Pennsylvania. What varies is your own parcel.
Across Pennsylvania’s 67 counties the frost-free season runs from 160 days in Potter County to 250 days in Philadelphia County — a spread of 90 days, which is why a single statewide planting date misleads. The median Pennsylvania county sees 197 frost-free days, leaving california poppy about 137 days of slack on a typical parcel — room for a second sowing where the season runs long.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). California Poppy's 60-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
California Poppy draws native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, california poppy can only work that bloom inside Pennsylvania's frost window — roughly 197 days, opening after the last 28°F freeze (Apr 6 - Apr 24) and closing at the first (Oct 25 - Nov 3), per NOAA Regional Climate Centers ACIS, 1991-2020.
Good to Know Before You Plant California Poppy
California Poppy is listed as toxic to dogs, cats (all) at a mild level (Pet Poison Helpline). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear.
Recommended California Poppy Varieties for Pennsylvania
Pennsylvania publishes no state variety trial for california poppy, so we won't invent a "best for Pennsylvania" list. Choose types rated to your USDA hardiness zone (5b-8a), and confirm winter survival and drainage against your own parcel.
Pennsylvania Cooperative Extension
For Pennsylvania-specific cultivar recommendations, planting calendars, and pest pressure for california poppy, the canonical source is Penn State Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is California Poppy native to Pennsylvania?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents California Poppy as native to Pennsylvania. Planting it supports the pollinators and wildlife that evolved alongside it.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing California Poppy in Pennsylvania
When can I plant California Poppy in Pennsylvania?
Pennsylvania's last spring hard freeze (28°F) clears between Apr 6 and Apr 24, and the first fall hard freeze lands between Oct 25 and Nov 3 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for California Poppy, so this page does not state whether it overwinters in Pennsylvania and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is California Poppy grown in across Pennsylvania?
Pennsylvania spans USDA hardiness zones 5b-8a (USDA ARS PHZM 2023). California Poppy carries a range of zones 6-10, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Pennsylvania site have?
A typical Pennsylvania site sees ~197 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). California Poppy needs 60+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Potter, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is California Poppy native to Pennsylvania?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents California Poppy as native to Pennsylvania. Planting it supports the pollinators and wildlife that evolved alongside it.
How should I amend the soil for California Poppy in Pennsylvania?
California Poppy tolerates pH 5-8 and well (dry spells) drainage (Growable Ground Plant Database). That is a 3-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Pennsylvania site — amend for drainage and organic matter first.
Will California Poppy actually grow on my specific land in Pennsylvania?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores california poppy against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Pennsylvania
State-level data is a sketch. Your Growable Ground report scores california poppy against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Pennsylvania california poppy averages can't show:
We read public map data around Pennsylvania — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Pennsylvania california poppy average
Explore More
Growing guides for california poppy
Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →
Cite this dataset
Kirchick, M. (2026). Growable Ground Plant Database [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21435643
Licensed CC BY-NC 4.0. DOI 10.5281/zenodo.21435643
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