Johnstown, PA planting zone & frost dates
Johnstown is in USDA hardiness zone 6b. The last spring frost usually comes around May 17 and the first fall frost around October 2, for a growing season of about 136 days.
Planting calendar for Johnstown
Dates are counted from the average last spring frost (May 17) 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: Mar 22 – Apr 5 Transplant outdoors: May 24 – May 31 |
| Peppers | Start seeds indoors: Mar 8 – Mar 22 Transplant outdoors: May 31 – Jun 7 |
| Eggplant | Start seeds indoors: Mar 8 – Mar 22 Transplant outdoors: May 31 – Jun 7 |
| Broccoli | Start seeds indoors: Mar 8 – Mar 22 Transplant outdoors: Apr 19 – May 3 |
| Cabbage | Start seeds indoors: Mar 8 – Mar 22 Transplant outdoors: Apr 19 – May 3 |
| Onions (sets) | Plant outdoors: Apr 19 – May 3 |
| Peas | Sow outdoors: Apr 5 – Apr 19 |
| Spinach | Sow outdoors: Apr 5 – Apr 19 |
| Lettuce | Sow outdoors: Apr 19 – May 3 |
| Carrots | Sow outdoors: Apr 19 – May 3 |
| Potatoes | Plant outdoors: Apr 19 – May 3 |
| Beans | Sow outdoors: May 24 – May 31 |
| Sweet corn | Sow outdoors: May 24 – May 31 |
| Cucumbers | Sow outdoors: May 24 – May 31 |
| Squash & zucchini | Sow outdoors: May 24 – May 31 |
| Basil | Start seeds indoors: Apr 5 – Apr 19 Transplant outdoors: May 24 – May 31 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 7 (8 weeks before the average first fall frost on Oct 2).
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 30 | May 17 | Jun 1 |
| First 32°F frost in fall is before | Oct 14 | Oct 2 | Sep 19 |
How to read it: in spring there is a 10% chance of a frost after June 1, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 19. A hard freeze (28°F) usually ends around May 4.
Hardiness zone by ZIP code in Johnstown
- 15901 zone 6b
- 15902 zone 6b
- 15904 zone 6b
- 15905 zone 6a
- 15906 zone 6b
- 15907 zone 6b
- 15909 zone 6b
- 15915 zone 6b
Nearby cities
- Indiana zone 6b, last frost May 8
- Altoona zone 6b, last frost Apr 25
- Greensburg zone 6b, last frost May 1
- Murrysville zone 6b, last frost Apr 22
- Plum zone 6b, last frost Apr 16
- Natrona Heights zone 6b, last frost Apr 16
- Lower Burrell zone 6b, last frost Apr 16
- Monroeville zone 6b, last frost Apr 22
Questions
What growing zone is Johnstown, PA?
Johnstown 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 Johnstown?
The average last spring frost (32°F) in Johnstown is May 17. There is still a 10% chance of frost until June 1.
When can I plant tomatoes in Johnstown?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 24 – May 31. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Ebensburg Sewage Plt, PA (USC00362470), 22.6 km (14.0 mi) from the city center, elevation 591 m, based on 29 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.