USDA hardiness zones — 2023 map
Pennsylvania hardiness zones — USDA planting zone map + what to grow
Zones 5a-7b · most of Pennsylvania is zone 6b · Northeast region
PennsylvaniaUSDA zone range & map
On the 2023 USDA Plant Hardiness Zone Map, Pennsylvania spans zones 5a-7b. The map shades the state from the northern Allegheny plateau (zone 5a) through to the southeast around Philadelphia (zone 7b). The single most common half-zone across the populated state is zone 6b — that is the figure to use if you only remember one number for Pennsylvania. Pennsylvania runs from cold northern mountains to a mild southeastern corner. Philadelphia gardens almost two zones warmer than the northern tier.
| USDA zone range | Zones 5a-7b |
|---|---|
| Most common zone | Zone 6b |
| Coldest area | the northern Allegheny plateau (zone 5a) |
| Warmest area | the southeast around Philadelphia (zone 7b) |
| Average last spring frost | late April |
| Average first fall frost | mid-October |
Source: USDA 2023 Plant Hardiness Zone Map (1991-2020 normals). Frost averages: NOAA/NCEI 1991-2020 climate normals. Local ZIP-level zones and frost dates can differ from these statewide figures.
Pennsylvania hardiness zones by major city
Zones shift across Pennsylvania with elevation and distance from the coast. Here is the 2023 USDA half-zone for the largest cities:
| City | USDA zone |
|---|---|
| Philadelphia | Zone 7b |
| Pittsburgh | Zone 6b |
| Harrisburg | Zone 7a |
| Allentown | Zone 6b |
| Erie | Zone 6b |
Need your exact zone? Run the ZIP-code zone finder for a precise half-zone and frost dates for your address.
ZIP-code zones in Pennsylvania
Statewide ranges hide a lot. Tap your area for its exact USDA half-zone, last and first frost dates, and what to plant now:
- Pittsburgh (East Liberty) 15206 — Zone 6b
- Pittsburgh (Oakland) 15213 — Zone 6b
- Pittsburgh 15222 — Zone 6b
- Erie 16501 — Zone 6b
- Altoona 16602 — Zone 6a
- State College 16801 — Zone 6a
- Harrisburg 17101 — Zone 7a
- York 17404 — Zone 7a
- Lancaster 17602 — Zone 7a
- Allentown 18101 — Zone 6b
- Allentown (West) 18102 — Zone 6b
- Scranton 18503 — Zone 6a
- Wilkes-Barre 18701 — Zone 6a
- Philadelphia 19102 — Zone 7b
- Philadelphia (Center City) 19103 — Zone 7b
- Philadelphia (University City) 19104 — Zone 7b
- Philadelphia (Fox Chase) 19111 — Zone 7a
- Philadelphia (Olney) 19120 — Zone 7b
- Philadelphia (Frankford) 19124 — Zone 7b
- Philadelphia (Southwest) 19143 — Zone 7b
- Reading 19601 — Zone 7a
What Pennsylvania's zone range means for planting
Your hardiness zone tells you which perennials, shrubs, and trees will survive a typical Pennsylvania winter, and it anchors when tender crops can go outside. Because Pennsylvania spans 5a-7b, two gardeners in the same state can have very different planting calendars.
- Pick perennials hardy to your local zone. Across most of Pennsylvania that means at least zone 6b; gardeners in the northern Allegheny plateau (zone 5a) should choose hardier plants.
- Anchor tender crops to your frost dates. With a last spring frost around late April and first fall frost around mid-October, set out tomatoes, peppers, and basil after the last frost and protect them before the first.
- Adjust for your microclimate. Urban heat, a south-facing slope, or a cold valley pocket can shift your effective zone and frost dates by a half-zone or more from the statewide figure.
Find your exact zone in Pennsylvania
The 5a-7b range is statewide. Growli pins your hardiness zone and frost dates to your exact ZIP code and sends a push notification before any forecast frost night for your saved location.
Frequently asked questions
What hardiness zone is Pennsylvania?
Pennsylvania spans USDA hardiness zones 5a-7b on the 2023 USDA Plant Hardiness Zone Map. The most common zone — covering the largest share of the populated state — is zone 6b. The coldest areas are the northern Allegheny plateau (zone 5a) and the warmest are the southeast around Philadelphia (zone 7b).
When is the last frost in Pennsylvania?
Across most of Pennsylvania the average last spring frost falls around late April and the first fall frost around mid-October. These are statewide averages — colder, higher areas run later in spring and earlier in fall, so check a ZIP-level estimate for your exact spot.
What grows well in Pennsylvania?
Pennsylvania runs from cold northern mountains to a mild southeastern corner. Philadelphia gardens almost two zones warmer than the northern tier. Match plants to your local half-zone within the 5a-7b range: choose varieties hardy to at least zone 6b for reliable overwintering, and time tender crops around your local frost dates. The zone 6 planting guide lists vegetables, fruit, and ornamentals suited to most of the state.
Why does Pennsylvania have more than one hardiness zone?
Hardiness zones track the average annual coldest temperature, which changes with latitude, elevation, distance from water, and urban heat. That is why Pennsylvania ranges from the northern Allegheny plateau (zone 5a) to the southeast around Philadelphia (zone 7b) — a span of 5a-7b — even though it is a single state.
Did Pennsylvania's hardiness zone change in 2023?
The USDA updated the Plant Hardiness Zone Map in November 2023 using 1991-2020 climate data. About half the country, including parts of Pennsylvania, shifted to the next warmer half-zone versus the 2012 map. The 5a-7b range here reflects the current 2023 map. Always confirm your address against the official USDA map for plant-survival decisions.