Fort Madison, IA planting zone & frost dates
Fort Madison is in USDA hardiness zone 6a. The last spring frost usually comes around April 12 and the first fall frost around October 25, for a growing season of about 194 days.
Planting calendar for Fort Madison
Dates are counted from the average last spring frost (April 12) 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: Feb 15 – Mar 1 Transplant outdoors: Apr 19 – Apr 26 |
| Peppers | Start seeds indoors: Feb 1 – Feb 15 Transplant outdoors: Apr 26 – May 3 |
| Eggplant | Start seeds indoors: Feb 1 – Feb 15 Transplant outdoors: Apr 26 – May 3 |
| Broccoli | Start seeds indoors: Feb 1 – Feb 15 Transplant outdoors: Mar 15 – Mar 29 |
| Cabbage | Start seeds indoors: Feb 1 – Feb 15 Transplant outdoors: Mar 15 – Mar 29 |
| Onions (sets) | Plant outdoors: Mar 15 – Mar 29 |
| Peas | Sow outdoors: Mar 1 – Mar 15 |
| Spinach | Sow outdoors: Mar 1 – Mar 15 |
| Lettuce | Sow outdoors: Mar 15 – Mar 29 |
| Carrots | Sow outdoors: Mar 15 – Mar 29 |
| Potatoes | Plant outdoors: Mar 15 – Mar 29 |
| Beans | Sow outdoors: Apr 19 – Apr 26 |
| Sweet corn | Sow outdoors: Apr 19 – Apr 26 |
| Cucumbers | Sow outdoors: Apr 19 – Apr 26 |
| Squash & zucchini | Sow outdoors: Apr 19 – Apr 26 |
| Basil | Start seeds indoors: Mar 1 – Mar 15 Transplant outdoors: Apr 19 – Apr 26 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 30 (8 weeks before the average first fall frost on Oct 25).
Useful for zone 6a 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 1 | Apr 12 | Apr 26 |
| First 32°F frost in fall is before | Nov 6 | Oct 25 | Oct 11 |
How to read it: in spring there is a 10% chance of a frost after April 26, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 11. A hard freeze (28°F) usually ends around April 3.
Hardiness zone by ZIP code in Fort Madison
- 52627 zone 6a
Nearby cities
- Keokuk zone 6a, last frost Apr 10
- Burlington zone 6a, last frost Apr 15
- Muscatine zone 5b, last frost Apr 18
- Iowa City zone 5b, last frost Apr 21
- Coralville zone 5b, last frost Apr 21
- North Liberty zone 5b, last frost Apr 21
- Davenport zone 5b, last frost Apr 19
- Ottumwa zone 5b, last frost Apr 23
Questions
What growing zone is Fort Madison, IA?
Fort Madison is in USDA Plant Hardiness Zone 6a (average extreme winter low -10°F to -5°F), according to the USDA 2023 map.
When is the last frost in Fort Madison?
The average last spring frost (32°F) in Fort Madison is April 12. There is still a 10% chance of frost until April 26.
When can I plant tomatoes in Fort Madison?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 19 – Apr 26. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Ft Madison, IA (USC00133007), 1.8 km (1.1 mi) from the city center, elevation 162 m, based on 28 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.