Washington, PA planting zone & frost dates
Washington is in USDA hardiness zone 6b. The last spring frost usually comes around April 24 and the first fall frost around October 23, for a growing season of about 181 days.
Planting calendar for Washington
Dates are counted from the average last spring frost (April 24) 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 27 – Mar 13 Transplant outdoors: May 1 – May 8 |
| Peppers | Start seeds indoors: Feb 13 – Feb 27 Transplant outdoors: May 8 – May 15 |
| Eggplant | Start seeds indoors: Feb 13 – Feb 27 Transplant outdoors: May 8 – May 15 |
| Broccoli | Start seeds indoors: Feb 13 – Feb 27 Transplant outdoors: Mar 27 – Apr 10 |
| Cabbage | Start seeds indoors: Feb 13 – Feb 27 Transplant outdoors: Mar 27 – Apr 10 |
| Onions (sets) | Plant outdoors: Mar 27 – Apr 10 |
| Peas | Sow outdoors: Mar 13 – Mar 27 |
| Spinach | Sow outdoors: Mar 13 – Mar 27 |
| Lettuce | Sow outdoors: Mar 27 – Apr 10 |
| Carrots | Sow outdoors: Mar 27 – Apr 10 |
| Potatoes | Plant outdoors: Mar 27 – Apr 10 |
| Beans | Sow outdoors: May 1 – May 8 |
| Sweet corn | Sow outdoors: May 1 – May 8 |
| Cucumbers | Sow outdoors: May 1 – May 8 |
| Squash & zucchini | Sow outdoors: May 1 – May 8 |
| Basil | Start seeds indoors: Mar 13 – Mar 27 Transplant outdoors: May 1 – May 8 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 28 (8 weeks before the average first fall frost on Oct 23).
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 8 | Apr 24 | May 18 |
| First 32°F frost in fall is before | Nov 5 | Oct 23 | Oct 8 |
How to read it: in spring there is a 10% chance of a frost after May 18, 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 11.
Hardiness zone by ZIP code in Washington
- 15301 zone 6b
Nearby cities
- Upper Saint Clair zone 6b, last frost Apr 18
- Bethel Park zone 6b, last frost Apr 18
- Mount Lebanon zone 6b, last frost Apr 18
- South Park Township zone 6b, last frost Apr 18
- Baldwin zone 6b, last frost Apr 18
- Whitehall zone 6b, last frost Apr 18
- Jefferson Hills zone 6b, last frost Apr 18
- Carnot-Moon zone 6b, last frost Apr 28
Questions
What growing zone is Washington, PA?
Washington is in USDA Plant Hardiness Zone 6b (average extreme winter low -5°F to 0°F), according to the USDA 2023 map.
When is the last frost in Washington?
The average last spring frost (32°F) in Washington is April 24. There is still a 10% chance of frost until May 18.
When can I plant tomatoes in Washington?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 1 – May 8. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Washington 3 Ne, PA (USC00369318), 4.9 km (3.0 mi) from the city center, elevation 396 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.