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Pennsylvania frost dates
Across the 25Pennsylvania weather stations below, the average last spring frost ranges from Apr 2 in Philadelphia to May 18 in Bradford. The statewide middle is about Apr 23 for the last spring frost and Oct 23 for the first fall frost. Philadelphia has the longest growing season, about 222 days. Hardiness zones in these places: 5b, 6a, 6b, 7a, 7b.
Frost dates by city
| Place | Zone | Last spring frost | 90% safe after | First fall frost | Frost-free days |
|---|---|---|---|---|---|
| Philadelphia | 7b | Apr 2 | Apr 13 | Nov 10 | 222 |
| Philadelphia Ne | 7b | Apr 4 | Apr 17 | Nov 7 | 217 |
| Harrisburg Cptl Cy | 7a | Apr 9 | Apr 25 | Nov 1 | 206 |
| Middletown Harrisburg | 7a | Apr 9 | Apr 25 | Nov 2 | 207 |
| Willow Grove | 7a | Apr 11 | Apr 27 | Nov 1 | 204 |
| Doylestown | 7a | Apr 13 | Apr 27 | Oct 30 | 200 |
| Reading Spaatz | 7a | Apr 14 | Apr 30 | Oct 29 | 198 |
| Lancaster | 7a | Apr 18 | May 5 | Oct 25 | 190 |
| Pittsburgh Allegheny | 6b | Apr 18 | May 6 | Oct 28 | 193 |
| Avondale 2 N | 7a | Apr 19 | May 3 | Oct 26 | 190 |
| Allentown | 7a | Apr 20 | May 6 | Oct 24 | 187 |
| Pottstown Limerick | 7a | Apr 20 | May 6 | Oct 23 | 186 |
| Altoona Blair | 6b | Apr 23 | May 11 | Oct 21 | 181 |
| Pittsburgh | 6b | Apr 23 | May 12 | Oct 23 | 183 |
| Wilkes-Barre | 6b | Apr 23 | May 10 | Oct 20 | 180 |
| Williamsport | 6b | Apr 24 | May 11 | Oct 23 | 182 |
| Erie | 6b | Apr 26 | May 13 | Nov 4 | 192 |
| Selinsgrove Penn Vly | 6b | Apr 27 | May 12 | Oct 16 | 172 |
| York | 6b | Apr 27 | May 11 | Oct 18 | 174 |
| Johnstown Cambria | 6b | Apr 29 | May 17 | Oct 21 | 175 |
| Port Meadville | 6a | Apr 30 | May 18 | Oct 23 | 176 |
| Clearfield Lawrence | 6a | May 4 | May 22 | Oct 11 | 160 |
| Dubois Jefferson | 6a | May 6 | May 23 | Oct 14 | 161 |
| Mt Pocono Mountains | 6a | May 6 | May 23 | Oct 8 | 155 |
| Bradford | 5b | May 18 | May 31 | Oct 1 | 136 |
Dates are the 50% probability of a 32°F freeze (NOAA 1991–2020 normals); "90% safe after" is the date after which a later spring freeze happens in only 1 year in 10.
When to plant in Pennsylvania
Using the statewide middle dates (last frost Apr 23, first frost Oct 23). Adjust for your town with the table above or the planting calendar.
| Plant | When to plant in Pennsylvania |
|---|---|
| Tomatoes | Apr 30 – May 14 |
| Peas | Mar 12 – Apr 2; fall: Jul 31 – Aug 21 |
| Potatoes | Mar 26 – Apr 16 |
| Green beans | Apr 30 – May 14; fall: Aug 7 – Aug 21 |
| Garlic | Oct 23 – Nov 20 |
| Tulips | Oct 9 – Nov 20 |