Williamsport, PA planting zone & frost dates
Williamsport is in USDA hardiness zone 6b. The last spring frost usually comes around April 25 and the first fall frost around October 24, for a growing season of about 181 days.
Planting calendar for Williamsport
Dates are counted from the average last spring frost (April 25) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Feb 28 – Mar 14 Transplant outdoors: May 2 – May 9 |
| Peppers | Start seeds indoors: Feb 14 – Feb 28 Transplant outdoors: May 9 – May 16 |
| Eggplant | Start seeds indoors: Feb 14 – Feb 28 Transplant outdoors: May 9 – May 16 |
| Broccoli | Start seeds indoors: Feb 14 – Feb 28 Transplant outdoors: Mar 28 – Apr 11 |
| Cabbage | Start seeds indoors: Feb 14 – Feb 28 Transplant outdoors: Mar 28 – Apr 11 |
| Onions (sets) | Plant outdoors: Mar 28 – Apr 11 |
| Peas | Sow outdoors: Mar 14 – Mar 28 |
| Spinach | Sow outdoors: Mar 14 – Mar 28 |
| Lettuce | Sow outdoors: Mar 28 – Apr 11 |
| Carrots | Sow outdoors: Mar 28 – Apr 11 |
| Potatoes | Plant outdoors: Mar 28 – Apr 11 |
| Beans | Sow outdoors: May 2 – May 9 |
| Sweet corn | Sow outdoors: May 2 – May 9 |
| Cucumbers | Sow outdoors: May 2 – May 9 |
| Squash & zucchini | Sow outdoors: May 2 – May 9 |
| Basil | Start seeds indoors: Mar 14 – Mar 28 Transplant outdoors: May 2 – May 9 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 29 (8 weeks before the average first fall frost on Oct 24).
Useful for zone 6b gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Cold frame / mini greenhouse — adds weeks to a short season
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Apr 10 | Apr 25 | May 12 |
| First 32°F frost in fall is before | Nov 5 | Oct 24 | Oct 8 |
How to read it: in spring there is a 10% chance of a frost after May 12, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 8. A hard freeze (28°F) usually ends around April 10.
Hardiness zone by ZIP code in Williamsport
- 17701 zone 6a
- 17702 zone 6b
- 17703 zone 6b
- 17705 zone 6b
Nearby cities
- Bloomsburg zone 6b, last frost Apr 27
- Berwick zone 6b, last frost May 4
- Colonial Park zone 7a, last frost Apr 15
- State College zone 6b, last frost Apr 20
- Harrisburg zone 7a, last frost Apr 15
- Pottsville zone 6b, last frost Apr 16
- Nanticoke zone 6b, last frost May 7
- Back Mountain zone 6a, last frost Apr 23
Questions
What growing zone is Williamsport, PA?
Williamsport is in USDA Plant Hardiness Zone 6b (average extreme winter low -5°F to 0°F), according to the USDA 2023 map. Some ZIP codes of the city fall in zone 6a.
When is the last frost in Williamsport?
The average last spring frost (32°F) in Williamsport is April 25. There is still a 10% chance of frost until May 12.
When can I plant tomatoes in Williamsport?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 2 – May 9. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Williamsport 2, PA (USC00369735), 1.7 km (1.1 mi) from the city center, elevation 160 m, based on 22 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.