Yes — Strong Match
mountain laurel (zones 5-11) covers every zone Pennsylvania contains (5b-8a), so hardiness is not what limits it anywhere in the state.
Mountain Laurel in Pennsylvania — the short answer
Mountain Laurel in Pennsylvania: hardy in zones 5–11, shade, against a state median of ~197 frost-free days.
- Plant zones
- 5-11
- 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
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 mountain laurel 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 mountain laurel 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
Even within Pennsylvania's zones 5b-8a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for mountain laurel (USDA PHZM 2023):
Zone Comparison
Mountain Laurel Needs
- USDA Zones: 5-11
- Frost-Free Days: 150+
- Sun: Shade
- Mature size: 10 ft tall
- 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 5-11)
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 Mountain Laurel 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.
Winter standing
Pennsylvania runs as cold as USDA zone 5, and no sourced winter-hardiness floor is on record for mountain laurel, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether mountain laurel 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 mountain laurel survives winter here. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Mountain Laurel wants 150+ frost-free days; a typical Pennsylvania site sees ~197 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves a workable window — start indoors to bank time.
Chill hours
Mountain Laurel requires ~600 chill hours (32-45°F dormancy window). Pennsylvania typically banks ~2500 chill hours per winter (from PRISM 1991-2020 climate normals), which keeps this plant on track.
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
Mountain Laurel prefers acidic soil (pH 4.5-5.5). Pennsylvania's silt loam can run on the acidic side, which often aligns well — confirm with a soil test before planting.
Your land, not the state average
Pennsylvania's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel. What matters for mountain laurel is the horizon its roots actually work, not the surface. That map unit, not the state average, decides how mountain laurel performs.
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.
What Else to Consider for Mountain Laurel 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 mountain laurel here specifically
Mountain Laurel needs pH 4.5–5.5; Pennsylvania's dominant silt loam soils may or may not deliver that, so your parcel's SSURGO map unit is the real test.
Start with a soil test on your own ground and adjust pH and texture to fit mountain laurel's 4.5–5.5 range. How to handle it →
What to actually do about these — and the constraints that apply to every Pennsylvania grower, not just mountain laurel — 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 mountain laurel to your county's window, not the statewide date.
Mountain Laurel needs about 150 days of frost-free season to complete its cycle. Even Potter County — Pennsylvania’s shortest season at 160 frost-free days — clears that by 10 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 mountain laurel about 47 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"). Mountain Laurel's 150-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
Mountain Laurel draws native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, mountain laurel 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 Mountain Laurel
Mountain Laurel is listed as toxic to dogs, cats, horses (all) at a severe level (ASPCA). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear.
Pennsylvania Cooperative Extension
For Pennsylvania-specific cultivar recommendations, planting calendars, and pest pressure for mountain laurel, the canonical source is Penn State Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Mountain Laurel native to Pennsylvania?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Mountain Laurel 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 Mountain Laurel in Pennsylvania
When can I plant Mountain Laurel 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 Mountain Laurel, 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 Mountain Laurel grown in across Pennsylvania?
Pennsylvania spans USDA hardiness zones 5b-8a (USDA ARS PHZM 2023). Mountain Laurel carries a range of zones 5-11, 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). Mountain Laurel needs 150+ 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 Mountain Laurel native to Pennsylvania?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Mountain Laurel as native to Pennsylvania. Planting it supports the pollinators and wildlife that evolved alongside it.
How should I amend the soil for Mountain Laurel in Pennsylvania?
Mountain Laurel prefers pH 4.5-5.5 (USDA PLANTS). Most Pennsylvania soils run mildly acidic to neutral; many sites land near this band naturally, and a soil test plus targeted sulfur or organic amendment closes any gap.
Will Mountain Laurel actually grow on my specific land in Pennsylvania?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores mountain laurel 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 mountain laurel against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Pennsylvania mountain laurel 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 mountain laurel average
Explore More
Growing guides for mountain laurel
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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