Philadelphia, Pennsylvania: planting zone & frost dates
Philadelphia is in USDA plant hardiness zone 7b, where the average coldest winter night reaches 5 to 10°F (-15.0 to -12.2°C). The typical last spring frost is around Apr 4 and the first fall frost around Nov 11.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Apr 12 | Nov 4 |
| Typical planning date (30% risk) | Apr 4 | Nov 11 |
| Median (50%) | Mar 30 | Nov 17 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station PHILA FRANKLIN INST, PA (USC00366886), 4.1 mi (6.6 km) from the city center and 39 ft lower than the city center (-12 m). Record used for the 1991–2020 normals: 25 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Philadelphia
All 49 ZIP codes covering Philadelphia are in zone 7b.
ZIP codes in Philadelphia and their zones
| ZIP | Zone | Share of city land |
|---|---|---|
| 19153 | 7b | 5.4% |
| 19128 | 7b | 5.1% |
| 19154 | 7b | 4.8% |
| 19114 | 7b | 4.2% |
| 19116 | 7b | 3.9% |
| 19131 | 7b | 3.9% |
| 19115 | 7b | 3.8% |
| 19124 | 7b | 3.8% |
| 19111 | 7b | 3.6% |
| 19136 | 7b | 3.6% |
| 19145 | 7b | 3.6% |
| 19148 | 7b | 3.2% |
| 19144 | 7b | 2.7% |
| 19134 | 7b | 2.6% |
| 19119 | 7b | 2.5% |
| 19120 | 7b | 2.4% |
| 19104 | 7b | 2.3% |
| 19118 | 7b | 2.3% |
| 19140 | 7b | 2.3% |
| 19143 | 7b | 2.3% |
| 19152 | 7b | 2.1% |
| 19121 | 7b | 1.8% |
| 19137 | 7b | 1.8% |
| 19149 | 7b | 1.8% |
| 19151 | 7b | 1.8% |
| 19135 | 7b | 1.7% |
| 19132 | 7b | 1.6% |
| 19129 | 7b | 1.5% |
| 19112 | 7b | 1.3% |
| 19138 | 7b | 1.3% |
| 19139 | 7b | 1.3% |
| 19141 | 7b | 1.3% |
| 19142 | 7b | 1.3% |
| 19146 | 7b | 1.3% |
| 19150 | 7b | 1.1% |
| 19122 | 7b | 1.0% |
| 19125 | 7b | 1.0% |
| 19133 | 7b | 1.0% |
| 19147 | 7b | 1.0% |
| 19123 | 7b | 0.9% |
| 19126 | 7b | 0.9% |
| 19130 | 7b | 0.9% |
| 19106 | 7b | 0.6% |
| 19103 | 7b | 0.5% |
| 19107 | 7b | 0.4% |
| 19127 | 7b | 0.4% |
| 19102 | 7b | 0.1% |
| 19108 | 7b | 0.0% |
| 19109 | 7b | 0.0% |
Vegetable planting calendar for Philadelphia
Dates are counted from the 30%-risk frost dates above (last frost Apr 4, first frost Nov 11). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Feb 7 – Feb 21 | Apr 11 – Apr 25 | — | — |
| Pepper | Jan 24 – Feb 7 | Apr 18 – May 2 | — | — |
| Lettuce | Feb 21 – Mar 7 | Mar 21 – Apr 11 | Mar 7 – Apr 18 | Sep 2 – Sep 30 |
| Green Beans | — | — | Apr 11 – May 16 | Aug 19 – Sep 2 |
| Sweet Corn | — | — | Apr 11 – May 9 | — |
| Zucchini & Summer Squash | Mar 7 – Mar 14 | Apr 11 – Apr 25 | Apr 11 – May 2 | Aug 19 – Sep 2 |
| Cucumber | Mar 7 – Mar 14 | Apr 18 – Apr 25 | Apr 11 – May 2 | Aug 19 – Sep 2 |
| Carrot | — | — | Mar 14 – Apr 18 | Aug 19 – Sep 2 |
| Onion | Jan 10 – Jan 24 | Mar 7 – Mar 21 | — | — |
| Potato | — | Mar 7 – Mar 28 | — | — |
| Basil | Feb 21 – Mar 7 | Apr 18 – May 2 | Apr 18 – May 9 | — |
| Spinach | — | — | Feb 21 – Mar 21 | Sep 16 – Oct 14 |
| Kale | Feb 7 – Feb 21 | Mar 7 – Mar 28 | Mar 7 – Mar 28 | Sep 2 – Sep 30 |
| Broccoli | Feb 7 – Feb 21 | Mar 21 – Apr 11 | — | Aug 19 – Sep 2 |
| Peas | — | — | Feb 21 – Mar 14 | Sep 2 – Sep 16 |
| Eggplant | Jan 24 – Feb 7 | Apr 18 – May 2 | — | — |
| Cabbage | Feb 7 – Feb 21 | Mar 7 – Mar 21 | — | Aug 19 – Sep 2 |
| Radish | — | — | Feb 28 – Apr 18 | Sep 30 – Oct 28 |
| Strawberry | — | Mar 7 – Mar 28 | — | — |
| Beets | — | — | Mar 14 – Apr 25 | Sep 2 – Sep 16 |
Nearby cities in Pennsylvania
- Bethlehem — zone 7a, last frost Apr 26, first frost Oct 17
- Allentown — zone 7a, last frost Apr 26, first frost Oct 17
- Reading — zone 7a, last frost Apr 21, first frost Oct 22
- Pittsburgh — zone 6b, last frost Apr 24, first frost Oct 22
- Erie — zone 6b, last frost May 2, first frost Oct 30
More: all Pennsylvania cities · other zone 7b cities: New York, NY, Oklahoma City, OK, Nashville, TN, Washington, DC, Baltimore, MD, Albuquerque, NM, Tulsa, OK, Newark, NJ
Philadelphia gardening questions
When is the last frost in Philadelphia, PA?
Plan around Apr 4. At NOAA's Phila Franklin Inst, PA station, 4.1 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Mar 30, and after Apr 12 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Mar 17. The last frost is fairly predictable here: only 28 days separate the 90% and 10% dates (median for cities on this site: 36 days).
When should I plant tomatoes in Philadelphia, PA?
Start seeds indoors Feb 7 – Feb 21 and set transplants outside Apr 11 – Apr 25, once nights stay above 50°F and the soil is near 60°F. That leaves 221 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Philadelphia?
About 232 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 214 days, and in 1 year in 10 it runs 255 days or more. In fall there is a 10% chance of frost by Nov 4 and a 30% chance by Nov 11. That is the longest of the 6 Pennsylvania cities on this site.
When should I plant a fall garden in Philadelphia?
Count back from the first fall frost (Nov 11): transplant broccoli Aug 19 – Sep 2; sow kale Sep 2 – Sep 30; sow lettuce Sep 2 – Sep 30; sow radishes Sep 30 – Oct 28. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Nov 29. How the math works: succession and fall planting.
Did Philadelphia's hardiness zone change on the 2023 map?
Yes. Most of Philadelphia was zone 7a on the 2012 map and is zone 7b on the 2023 map — half a zone warmer, like about 56% of U.S. ZIP codes. The shift comes from a newer 1991–2020 averaging period plus more weather stations and better mapping; it does not mean last frost comes earlier. Why the 2023 map is warmer.
How does Philadelphia compare with Trenton, NJ?
Philadelphia is zone 7b and Trenton is zone 7a. The typical last spring frost in Philadelphia (Apr 4) comes about 21 days earlier than in Trenton, NJ (Apr 25), 25 miles away, and the first fall frost is Nov 11 versus Oct 21. The two cities use different NOAA stations.