Yes — Strong Match
woodland phlox (zones 4-10) covers every zone Pennsylvania contains (5b-8a), so hardiness is not what limits it anywhere in the state.
Woodland Phlox in Pennsylvania — the short answer
Woodland Phlox in Pennsylvania: hardy in zones 4–10, part sun, against a state median of ~197 frost-free days.
- Plant zones
- 4-10
- 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
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 woodland phlox against your parcel's actual hardiness, soil, and sun.
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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 woodland phlox 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 woodland phlox (USDA PHZM 2023):
Zone Comparison
Woodland Phlox Needs
- USDA Zones: 4-10
- Frost-Free Days: 100+
- Sun: Part Sun
- Mature size: 1.3 ft tall
- Picking window: ~21 days of harvest
- Drought tolerance: Low
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 4-10)
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 Woodland Phlox 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 woodland phlox, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether woodland phlox 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.
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 woodland phlox survives winter here. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Woodland Phlox wants 100+ frost-free days; a typical Pennsylvania site sees ~197 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
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
Woodland Phlox likes near-neutral soil (pH 5.5-7.2). That's the common-ground band across Pennsylvania's silt loam and shale-derived — a soil test confirms it for your site.
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 Woodland Phlox 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
What to actually do about these — and the constraints that apply to every Pennsylvania grower, not just woodland phlox — is covered on the Pennsylvania growing guide.
Timing shifts within Pennsylvania
Woodland Phlox needs about 100 days of frost-free season to complete its cycle. Even Potter County — Pennsylvania’s shortest season at 160 frost-free days — clears that by 60 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 woodland phlox about 97 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"). Woodland Phlox's 100-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
Woodland Phlox draws native bees, butterflies, hummingbirds, and moths (high value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, woodland phlox 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.
Pennsylvania Cooperative Extension
For Pennsylvania-specific cultivar recommendations, planting calendars, and pest pressure for woodland phlox, the canonical source is Penn State Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Woodland Phlox native to Pennsylvania?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Woodland Phlox 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 Woodland Phlox in Pennsylvania
When can I plant Woodland Phlox 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 Woodland Phlox, 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 Woodland Phlox grown in across Pennsylvania?
Pennsylvania spans USDA hardiness zones 5b-8a (USDA ARS PHZM 2023). Woodland Phlox carries a range of zones 4-10, 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). Woodland Phlox needs 100+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Woodland Phlox native to Pennsylvania?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Woodland Phlox as native to Pennsylvania. Planting it supports the pollinators and wildlife that evolved alongside it.
How should I amend the soil for Woodland Phlox in Pennsylvania?
Woodland Phlox prefers pH 5.5-7.2 (USDA PLANTS). That sits in the common-ground band across Pennsylvania soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Woodland Phlox actually grow on my specific land in Pennsylvania?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores woodland phlox 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 woodland phlox against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Pennsylvania woodland phlox 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 woodland phlox average
Explore More
Growing guides for woodland phlox
Explore Pennsylvania county by county
Pennsylvania carries 67 counties with their own USDA zone — a sample of the growing pages for woodland phlox there:
Where else woodland phlox grows
Woodland Phlox's zone band crosses state lines — these are the states closest to Pennsylvania in winter climate where it also has a page, plus the far ends of its range. Each one re-answers the question with that state's own record.
More to grow in Pennsylvania
Pennsylvania has a growing page for 893 plants — a rotating sample of the rest of the shelf.
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