Frost dates for 50849Greenfield, IA
The average last spring frost in Greenfield is April 25 and the average first fall frost is October 12, giving a typical growing season of about 170 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 25
- Average first fall frost
- Oct 12
- Growing season
- 170 days
Safer after May 7 (1-in-10 risk)
Possible by Sep 26 (1-in-10 risk)
Last frost typically in 180 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 23 · May 4 · May 16 | Sep 19 · Oct 2 · Oct 17 | 150 days | 100% |
| Frost / freeze (32°F) | Apr 12 · Apr 25 · May 7 | Sep 26 · Oct 12 · Oct 26 | 170 days | 100% |
| Hard freeze (28°F) | Apr 3 · Apr 16 · Apr 29 | Oct 6 · Oct 23 · Nov 5 | 190 days | 100% |
Planting calendar for Greenfield
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 25 – May 31 |
| Tomatoes | Transplant outdoors | May 11 – Jun 22 |
| Peppers | Start seeds indoors | Mar 25 – Apr 25 |
| Peppers | Transplant outdoors | May 25 – Jun 25 |
| Eggplant | Start seeds indoors | Apr 11 – May 10 |
| Eggplant | Transplant outdoors | May 25 – Jun 25 |
| Cucumbers | Sow outdoors | May 25 – Jul 2 |
| Summer squash | Sow outdoors | May 11 – Jun 25 |
| Winter squash & pumpkins | Sow outdoors | May 25 – Jun 25 |
| Snap beans | Sow outdoors | May 11 – Jul 25 |
| Sweet corn | Sow outdoors | May 11 – Jun 22 |
| Watermelon & cantaloupe | Sow outdoors | May 25 – Jun 25 |
| Okra | Sow outdoors | May 18 – Jun 10 |
| Peas | Sow outdoors (spring) | Mar 25 – May 10 |
| Potatoes | Plant outdoors (spring) | Mar 25 – May 25 |
| Onions | Start seeds indoors (spring) | Feb 11 – Mar 10 |
| Onions | Transplant outdoors (spring) | Apr 11 – May 10 |
| Broccoli | Start seeds indoors (spring) | Mar 7 – Apr 10 |
| Broccoli | Transplant outdoors (spring) | Apr 11 – May 10 |
| Broccoli | Start seeds indoors (fall) | Jun 12 – Jun 22 |
| Broccoli | Transplant outdoors (fall) | Jul 12 – Jul 23 |
| Cabbage | Start seeds indoors (spring) | Feb 25 – Mar 25 |
| Cabbage | Transplant outdoors (spring) | Mar 25 – Apr 25 |
| Cabbage | Start seeds indoors (fall) | Jun 2 – Jul 2 |
| Cabbage | Transplant outdoors (fall) | Jul 2 – Aug 2 |
| Leaf lettuce | Sow outdoors (spring) | Mar 25 – Jun 10 |
| Leaf lettuce | Sow outdoors (fall) | Jul 2 – Aug 18 |
| Spinach | Sow outdoors (spring) | Mar 18 – May 1 |
| Spinach | Sow outdoors (fall) | Jul 19 – Aug 23 |
| Radishes | Sow outdoors (spring) | Mar 25 – May 15 |
| Radishes | Sow outdoors (fall) | Jul 2 – Sep 2 |
| Kale | Sow outdoors (spring) | Apr 11 – May 1 |
| Kale | Sow outdoors (fall) | Jun 25 – Aug 2 |
| Carrots | Sow outdoors (spring) | Apr 25 – Jun 10 |
| Carrots | Sow outdoors (fall) | Jun 2 – Jul 18 |
| Garlic | Plant outdoors (fall) | Oct 2 – Nov 2 |
Where these dates come from
ZIP code 50849 is matched to the NOAA station Greenfield, IA, 2.2 km away, at 1,316 ft elevation (39 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Greenfield, IA (used) | 1,316 ft | Apr 25 | Oct 12 |
| Creston 2 Sw, IA | 1,296 ft | Apr 28 | Oct 11 |
| Winterset 1S, IA | 1,100 ft | Apr 30 | Oct 3 |
| Guthrie Ctr, IA | 1,065 ft | May 2 | Oct 3 |
Frost dates near Greenfield
- Fontanelle, IA 50846 · last Apr 25, first Oct 12
- Orient, IA 50858 · last Apr 25, first Oct 12
- Bridgewater, IA 50837 · last Apr 25, first Oct 12
- Casey, IA 50048 · last May 2, first Oct 3
- Stuart, IA 50250 · last May 2, first Oct 3
- Macksburg, IA 50155 · last Apr 30, first Oct 3
- Menlo, IA 50164 · last May 2, first Oct 3
- Massena, IA 50853 · last Apr 30, first Oct 2
Frequently asked questions
- When is the last frost in Greenfield, IA?
- For ZIP code 50849, the average last spring frost (32°F) is April 25, based on NOAA 1991-2020 climate normals for the Greenfield, IA weather station. There is a 1-in-10 chance of a frost after May 7.
- When is the first frost in Greenfield, IA?
- The average first fall frost (32°F) is October 12. There is a 1-in-10 chance of frost by September 26, so tender plants are at risk from that point on.
- How long is the growing season in 50849?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 170 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.