Frost dates for 17064Mount Gretna, PA
The average last spring frost in Mount Gretna is April 20 and the average first fall frost is October 25, giving a typical growing season of about 185 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 20
- Average first fall frost
- Oct 25
- Growing season
- 185 days
Safer after May 7 (1-in-10 risk)
Possible by Oct 10 (1-in-10 risk)
Last frost typically in 168 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Apr 18 · May 2 · May 18 | Oct 1 · Oct 14 · Oct 28 | 164 days | 100% |
| Frost / freeze (32°F) | Apr 5 · Apr 20 · May 7 | Oct 10 · Oct 25 · Nov 6 | 185 days | 100% |
| Hard freeze (28°F) | Mar 22 · Apr 4 · Apr 18 | Oct 22 · Nov 5 · Nov 20 | 212 days | 100% |
Planting calendar for Mount Gretna
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Mar 20 – May 26 |
| Tomatoes | Transplant outdoors | May 6 – Jul 5 |
| Peppers | Start seeds indoors | Mar 20 – Apr 20 |
| Peppers | Transplant outdoors | May 20 – Jun 20 |
| Eggplant | Start seeds indoors | Apr 6 – May 5 |
| Eggplant | Transplant outdoors | May 20 – Jun 20 |
| Cucumbers | Sow outdoors | May 20 – Jul 15 |
| Summer squash | Sow outdoors | May 6 – Jun 20 |
| Winter squash & pumpkins | Sow outdoors | May 20 – Jun 20 |
| Snap beans | Sow outdoors | May 6 – Aug 7 |
| Sweet corn | Sow outdoors | May 6 – Jul 5 |
| Watermelon & cantaloupe | Sow outdoors | May 20 – Jun 20 |
| Okra | Sow outdoors | May 13 – Jun 5 |
| Peas | Sow outdoors (spring) | Mar 20 – May 5 |
| Potatoes | Plant outdoors (spring) | Mar 20 – May 20 |
| Onions | Start seeds indoors (spring) | Feb 6 – Mar 5 |
| Onions | Transplant outdoors (spring) | Apr 6 – May 5 |
| Broccoli | Start seeds indoors (spring) | Mar 2 – Apr 5 |
| Broccoli | Transplant outdoors (spring) | Apr 6 – May 5 |
| Broccoli | Start seeds indoors (fall) | Jun 25 – Jul 5 |
| Broccoli | Transplant outdoors (fall) | Jul 25 – Aug 5 |
| Cabbage | Start seeds indoors (spring) | Feb 20 – Mar 20 |
| Cabbage | Transplant outdoors (spring) | Mar 20 – Apr 20 |
| Cabbage | Start seeds indoors (fall) | Jun 15 – Jul 15 |
| Cabbage | Transplant outdoors (fall) | Jul 15 – Aug 15 |
| Leaf lettuce | Sow outdoors (spring) | Mar 20 – Jun 5 |
| Leaf lettuce | Sow outdoors (fall) | Jul 15 – Aug 31 |
| Spinach | Sow outdoors (spring) | Mar 13 – Apr 26 |
| Spinach | Sow outdoors (fall) | Aug 1 – Sep 5 |
| Radishes | Sow outdoors (spring) | Mar 20 – May 10 |
| Radishes | Sow outdoors (fall) | Jul 15 – Sep 15 |
| Kale | Sow outdoors (spring) | Apr 6 – Apr 26 |
| Kale | Sow outdoors (fall) | Jul 8 – Aug 15 |
| Carrots | Sow outdoors (spring) | Apr 20 – Jun 5 |
| Carrots | Sow outdoors (fall) | Jun 15 – Jul 31 |
| Garlic | Plant outdoors (fall) | Oct 15 – Nov 15 |
Where these dates come from
ZIP code 17064 is matched to the NOAA station Lebanon 2 W, PA, 9.5 km away, at 450 ft elevation (183 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Lebanon 2 W, PA (used) | 450 ft | Apr 20 | Oct 25 |
| Landisville 2 Nw, PA | 360 ft | Apr 30 | Oct 10 |
| Lancaster Ap, PA | 403 ft | Apr 18 | Oct 25 |
| Middletown Harrisburg Intl Ap, PA | 312 ft | Apr 9 | Nov 2 |
Frost dates near Mount Gretna
- Quentin, PA 17083 · last Apr 20, first Oct 25
- Lawn, PA 17041 · last Apr 20, first Oct 25
- Cornwall, PA 17016 · last Apr 20, first Oct 25
- Rexmont, PA 17085 · last Apr 20, first Oct 25
- Manheim, PA 17545 · last Apr 30, first Oct 10
- Campbelltown, PA 17010 · last Apr 20, first Oct 25
- Lebanon, PA 17042 · last Apr 20, first Oct 25
- Palmyra, PA 17078 · last Apr 20, first Oct 25
Frequently asked questions
- When is the last frost in Mount Gretna, PA?
- For ZIP code 17064, the average last spring frost (32°F) is April 20, based on NOAA 1991-2020 climate normals for the Lebanon 2 W, PA weather station. There is a 1-in-10 chance of a frost after May 7.
- When is the first frost in Mount Gretna, PA?
- The average first fall frost (32°F) is October 25. There is a 1-in-10 chance of frost by October 10, so tender plants are at risk from that point on.
- How long is the growing season in 17064?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 185 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.