Saint Marys, PA planting zone & frost dates
Saint Marys is in USDA hardiness zone 5b. The last spring frost usually comes around May 14 and the first fall frost around October 6, for a growing season of about 143 days.
Planting calendar for Saint Marys
Dates are counted from the average last spring frost (May 14) 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 19 – Apr 2 Transplant outdoors: May 21 – May 28 |
| Peppers | Start seeds indoors: Mar 5 – Mar 19 Transplant outdoors: May 28 – Jun 4 |
| Eggplant | Start seeds indoors: Mar 5 – Mar 19 Transplant outdoors: May 28 – Jun 4 |
| Broccoli | Start seeds indoors: Mar 5 – Mar 19 Transplant outdoors: Apr 16 – Apr 30 |
| Cabbage | Start seeds indoors: Mar 5 – Mar 19 Transplant outdoors: Apr 16 – Apr 30 |
| Onions (sets) | Plant outdoors: Apr 16 – Apr 30 |
| Peas | Sow outdoors: Apr 2 – Apr 16 |
| Spinach | Sow outdoors: Apr 2 – Apr 16 |
| Lettuce | Sow outdoors: Apr 16 – Apr 30 |
| Carrots | Sow outdoors: Apr 16 – Apr 30 |
| Potatoes | Plant outdoors: Apr 16 – Apr 30 |
| Beans | Sow outdoors: May 21 – May 28 |
| Sweet corn | Sow outdoors: May 21 – May 28 |
| Cucumbers | Sow outdoors: May 21 – May 28 |
| Squash & zucchini | Sow outdoors: May 21 – May 28 |
| Basil | Start seeds indoors: Apr 2 – Apr 16 Transplant outdoors: May 21 – May 28 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 11 (8 weeks before the average first fall frost on Oct 6).
Useful for zone 5b 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 28 | May 14 | May 29 |
| First 32°F frost in fall is before | Oct 20 | Oct 6 | Sep 24 |
How to read it: in spring there is a 10% chance of a frost after May 29, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 24. A hard freeze (28°F) usually ends around May 3.
Hardiness zone by ZIP code in Saint Marys
- 15857 zone 5b
Nearby cities
- Altoona zone 6b, last frost Apr 25
- State College zone 6b, last frost Apr 20
- Indiana zone 6b, last frost May 8
- Oil City zone 6a, last frost May 2
- Johnstown zone 6b, last frost May 17
- Natrona Heights zone 6b, last frost Apr 16
- Butler zone 6b, last frost May 7
- New Kensington zone 6b, last frost Apr 16
Questions
What growing zone is Saint Marys, PA?
Saint Marys is in USDA Plant Hardiness Zone 5b (average extreme winter low -15°F to -10°F), according to the USDA 2023 map.
When is the last frost in Saint Marys?
The average last spring frost (32°F) in Saint Marys is May 14. There is still a 10% chance of frost until May 29.
When can I plant tomatoes in Saint Marys?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 21 – May 28. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Glen Hazel 2 Ne Dam, PA (USC00363311), 15.1 km (9.4 mi) from the city center, elevation 524 m, based on 17 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.