Frost dates for 50635Gladbrook, IA
The average last spring frost in Gladbrook is April 30 and the average first fall frost is October 6, giving a typical growing season of about 159 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 30
- Average first fall frost
- Oct 6
- Growing season
- 159 days
Safer after May 12 (1-in-10 risk)
Possible by Sep 22 (1-in-10 risk)
Last frost typically in 185 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 26 · May 7 · May 20 | Sep 14 · Sep 26 · Oct 9 | 141 days | 100% |
| Frost / freeze (32°F) | Apr 15 · Apr 30 · May 12 | Sep 22 · Oct 6 · Oct 19 | 159 days | 100% |
| Hard freeze (28°F) | Apr 5 · Apr 19 · May 3 | Sep 30 · Oct 16 · Oct 28 | 179 days | 100% |
Planting calendar for Gladbrook
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 30 – Jun 5 |
| Tomatoes | Transplant outdoors | May 16 – Jun 16 |
| Peppers | Start seeds indoors | Mar 30 – Apr 30 |
| Peppers | Transplant outdoors | May 30 – Jun 30 |
| Eggplant | Start seeds indoors | Apr 16 – May 15 |
| Eggplant | Transplant outdoors | May 30 – Jun 30 |
| Cucumbers | Sow outdoors | May 30 – Jun 26 |
| Summer squash | Sow outdoors | May 16 – Jun 30 |
| Winter squash & pumpkins | Sow outdoors | May 30 – Jun 30 |
| Snap beans | Sow outdoors | May 16 – Jul 19 |
| Sweet corn | Sow outdoors | May 16 – Jun 16 |
| Watermelon & cantaloupe | Sow outdoors | May 30 – Jun 30 |
| Okra | Sow outdoors | May 23 – Jun 15 |
| Peas | Sow outdoors (spring) | Mar 30 – May 15 |
| Potatoes | Plant outdoors (spring) | Mar 30 – May 30 |
| Onions | Start seeds indoors (spring) | Feb 16 – Mar 15 |
| Onions | Transplant outdoors (spring) | Apr 16 – May 15 |
| Broccoli | Start seeds indoors (spring) | Mar 12 – Apr 15 |
| Broccoli | Transplant outdoors (spring) | Apr 16 – May 15 |
| Broccoli | Start seeds indoors (fall) | Jun 6 – Jun 16 |
| Broccoli | Transplant outdoors (fall) | Jul 6 – Jul 17 |
| Cabbage | Start seeds indoors (spring) | Mar 2 – Mar 30 |
| Cabbage | Transplant outdoors (spring) | Mar 30 – Apr 30 |
| Cabbage | Start seeds indoors (fall) | May 27 – Jun 26 |
| Cabbage | Transplant outdoors (fall) | Jun 26 – Jul 27 |
| Leaf lettuce | Sow outdoors (spring) | Mar 30 – Jun 15 |
| Leaf lettuce | Sow outdoors (fall) | Jun 26 – Aug 12 |
| Spinach | Sow outdoors (spring) | Mar 23 – May 6 |
| Spinach | Sow outdoors (fall) | Jul 13 – Aug 17 |
| Radishes | Sow outdoors (spring) | Mar 30 – May 20 |
| Radishes | Sow outdoors (fall) | Jun 26 – Aug 27 |
| Kale | Sow outdoors (spring) | Apr 16 – May 6 |
| Kale | Sow outdoors (fall) | Jun 19 – Jul 27 |
| Carrots | Sow outdoors (spring) | Apr 30 – Jun 15 |
| Carrots | Sow outdoors (fall) | May 27 – Jul 12 |
| Garlic | Plant outdoors (fall) | Sep 26 – Oct 27 |
Where these dates come from
ZIP code 50635 is matched to the NOAA station Marshalltown Muni Ap, IA, 18.2 km away, at 974 ft elevation (36 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Marshalltown Muni Ap, IA (used) | 974 ft | Apr 30 | Oct 6 |
| Toledo 3N, IA | 935 ft | Apr 30 | Oct 9 |
| Grundy Ctr, IA | 985 ft | Apr 29 | Oct 9 |
| Marshalltown, IA | 870 ft | Apr 28 | Oct 7 |
Frost dates near Gladbrook
- Lincoln, IA 50652 · last Apr 29, first Oct 9
- Garwin, IA 50632 · last Apr 30, first Oct 9
- Beaman, IA 50609 · last Apr 29, first Oct 9
- Conrad, IA 50621 · last Apr 30, first Oct 6
- Reinbeck, IA 50669 · last Apr 29, first Oct 9
- Morrison, IA 50657 · last Apr 29, first Oct 9
- Traer, IA 50675 · last Apr 30, first Oct 9
- Le Grand, IA 50142 · last Apr 30, first Oct 9
Frequently asked questions
- When is the last frost in Gladbrook, IA?
- For ZIP code 50635, the average last spring frost (32°F) is April 30, based on NOAA 1991-2020 climate normals for the Marshalltown Muni Ap, IA weather station. There is a 1-in-10 chance of a frost after May 12.
- When is the first frost in Gladbrook, IA?
- The average first fall frost (32°F) is October 6. There is a 1-in-10 chance of frost by September 22, so tender plants are at risk from that point on.
- How long is the growing season in 50635?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 159 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.