Keokuk, IA planting zone & frost dates
Keokuk is in USDA hardiness zone 6a. The last spring frost usually comes around April 10 and the first fall frost around October 27, for a growing season of about 198 days.
Planting calendar for Keokuk
Dates are counted from the average last spring frost (April 10) 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 13 – Feb 27 Transplant outdoors: Apr 17 – Apr 24 |
| Peppers | Start seeds indoors: Jan 30 – Feb 13 Transplant outdoors: Apr 24 – May 1 |
| Eggplant | Start seeds indoors: Jan 30 – Feb 13 Transplant outdoors: Apr 24 – May 1 |
| Broccoli | Start seeds indoors: Jan 30 – Feb 13 Transplant outdoors: Mar 13 – Mar 27 |
| Cabbage | Start seeds indoors: Jan 30 – Feb 13 Transplant outdoors: Mar 13 – Mar 27 |
| Onions (sets) | Plant outdoors: Mar 13 – Mar 27 |
| Peas | Sow outdoors: Feb 27 – Mar 13 |
| Spinach | Sow outdoors: Feb 27 – Mar 13 |
| Lettuce | Sow outdoors: Mar 13 – Mar 27 |
| Carrots | Sow outdoors: Mar 13 – Mar 27 |
| Potatoes | Plant outdoors: Mar 13 – Mar 27 |
| Beans | Sow outdoors: Apr 17 – Apr 24 |
| Sweet corn | Sow outdoors: Apr 17 – Apr 24 |
| Cucumbers | Sow outdoors: Apr 17 – Apr 24 |
| Squash & zucchini | Sow outdoors: Apr 17 – Apr 24 |
| Basil | Start seeds indoors: Feb 27 – Mar 13 Transplant outdoors: Apr 17 – Apr 24 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 1 (8 weeks before the average first fall frost on Oct 27).
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 | Mar 30 | Apr 10 | Apr 26 |
| First 32°F frost in fall is before | Nov 7 | Oct 27 | Oct 10 |
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 10. A hard freeze (28°F) usually ends around April 2.
Hardiness zone by ZIP code in Keokuk
- 52632 zone 6a
Nearby cities
- Fort Madison zone 6a, last frost Apr 12
- Burlington zone 6a, last frost Apr 15
- Muscatine zone 5b, last frost Apr 18
- Ottumwa zone 5b, last frost Apr 23
- 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
Questions
What growing zone is Keokuk, IA?
Keokuk 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 Keokuk?
The average last spring frost (32°F) in Keokuk is April 10. There is still a 10% chance of frost until April 26.
When can I plant tomatoes in Keokuk?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 17 – Apr 24. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Keokuk Lock Dam 19, IA (USC00134381), 0.8 km (0.5 mi) from the city center, elevation 161 m, based on 30 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.