Frost dates for 46759Keystone, IN
The average last spring frost in Keystone is April 22 and the average first fall frost is October 22, giving a typical growing season of about 181 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 22
- Average first fall frost
- Oct 22
- Growing season
- 181 days
Safer after May 7 (1-in-10 risk)
Possible by Oct 7 (1-in-10 risk)
Last frost typically in 171 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 17 | Sep 27 · Oct 11 · Oct 25 | 161 days | 100% |
| Frost / freeze (32°F) | Apr 6 · Apr 22 · May 7 | Oct 7 · Oct 22 · Nov 3 | 181 days | 100% |
| Hard freeze (28°F) | Mar 26 · Apr 10 · Apr 27 | Oct 20 · Nov 1 · Nov 15 | 205 days | 100% |
Planting calendar for Keystone
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 22 – May 28 |
| Tomatoes | Transplant outdoors | May 8 – Jul 2 |
| Peppers | Start seeds indoors | Mar 22 – Apr 22 |
| Peppers | Transplant outdoors | May 22 – Jun 22 |
| Eggplant | Start seeds indoors | Apr 8 – May 7 |
| Eggplant | Transplant outdoors | May 22 – Jun 22 |
| Cucumbers | Sow outdoors | May 22 – Jul 12 |
| Summer squash | Sow outdoors | May 8 – Jun 22 |
| Winter squash & pumpkins | Sow outdoors | May 22 – Jun 22 |
| Snap beans | Sow outdoors | May 8 – Aug 4 |
| Sweet corn | Sow outdoors | May 8 – Jul 2 |
| Watermelon & cantaloupe | Sow outdoors | May 22 – Jun 22 |
| Okra | Sow outdoors | May 15 – Jun 7 |
| Peas | Sow outdoors (spring) | Mar 22 – May 7 |
| Potatoes | Plant outdoors (spring) | Mar 22 – May 22 |
| Onions | Start seeds indoors (spring) | Feb 8 – Mar 7 |
| Onions | Transplant outdoors (spring) | Apr 8 – May 7 |
| Broccoli | Start seeds indoors (spring) | Mar 4 – Apr 7 |
| Broccoli | Transplant outdoors (spring) | Apr 8 – May 7 |
| Broccoli | Start seeds indoors (fall) | Jun 22 – Jul 2 |
| Broccoli | Transplant outdoors (fall) | Jul 22 – Aug 2 |
| Cabbage | Start seeds indoors (spring) | Feb 22 – Mar 22 |
| Cabbage | Transplant outdoors (spring) | Mar 22 – Apr 22 |
| Cabbage | Start seeds indoors (fall) | Jun 12 – Jul 12 |
| Cabbage | Transplant outdoors (fall) | Jul 12 – Aug 12 |
| Leaf lettuce | Sow outdoors (spring) | Mar 22 – Jun 7 |
| Leaf lettuce | Sow outdoors (fall) | Jul 12 – Aug 28 |
| Spinach | Sow outdoors (spring) | Mar 15 – Apr 28 |
| Spinach | Sow outdoors (fall) | Jul 29 – Sep 2 |
| Radishes | Sow outdoors (spring) | Mar 22 – May 12 |
| Radishes | Sow outdoors (fall) | Jul 12 – Sep 12 |
| Kale | Sow outdoors (spring) | Apr 8 – Apr 28 |
| Kale | Sow outdoors (fall) | Jul 5 – Aug 12 |
| Carrots | Sow outdoors (spring) | Apr 22 – Jun 7 |
| Carrots | Sow outdoors (fall) | Jun 12 – Jul 28 |
| Garlic | Plant outdoors (fall) | Oct 12 – Nov 12 |
Where these dates come from
ZIP code 46759 is matched to the NOAA station Hartford City 4 Ese, IN, 17.2 km away, at 924 ft elevation (81 ft higher than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Hartford City 4 Ese, IN (used) | 924 ft | Apr 22 | Oct 22 |
| Bluffton 6N, IN | 861 ft | Apr 24 | Oct 20 |
| Berne Wwtp, IN | 839 ft | Apr 23 | Oct 22 |
| Portland 1 Sw, IN | 910 ft | Apr 28 | Oct 15 |
Frost dates near Keystone
- Montpelier, IN 47359 · last Apr 22, first Oct 22
- Poneto, IN 46781 · last Apr 24, first Oct 20
- Petroleum, IN 46778 · last Apr 23, first Oct 22
- Liberty Center, IN 46766 · last Apr 24, first Oct 20
- Pennville, IN 47369 · last Apr 22, first Oct 22
- Warren, IN 46792 · last May 1, first Oct 14
- Hartford City, IN 47348 · last Apr 22, first Oct 22
- Bluffton, IN 46714 · last Apr 24, first Oct 20
Frequently asked questions
- When is the last frost in Keystone, IN?
- For ZIP code 46759, the average last spring frost (32°F) is April 22, based on NOAA 1991-2020 climate normals for the Hartford City 4 Ese, IN weather station. There is a 1-in-10 chance of a frost after May 7.
- When is the first frost in Keystone, IN?
- The average first fall frost (32°F) is October 22. There is a 1-in-10 chance of frost by October 7, so tender plants are at risk from that point on.
- How long is the growing season in 46759?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 181 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.