Grimes, IA planting zone & frost dates
Grimes is in USDA hardiness zone 5b. The last spring frost usually comes around April 19 and the first fall frost around October 18, for a growing season of about 179 days.
Planting calendar for Grimes
Dates are counted from the average last spring frost (April 19) 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 22 – Mar 8 Transplant outdoors: Apr 26 – May 3 |
| Peppers | Start seeds indoors: Feb 8 – Feb 22 Transplant outdoors: May 3 – May 10 |
| Eggplant | Start seeds indoors: Feb 8 – Feb 22 Transplant outdoors: May 3 – May 10 |
| Broccoli | Start seeds indoors: Feb 8 – Feb 22 Transplant outdoors: Mar 22 – Apr 5 |
| Cabbage | Start seeds indoors: Feb 8 – Feb 22 Transplant outdoors: Mar 22 – Apr 5 |
| Onions (sets) | Plant outdoors: Mar 22 – Apr 5 |
| Peas | Sow outdoors: Mar 8 – Mar 22 |
| Spinach | Sow outdoors: Mar 8 – Mar 22 |
| Lettuce | Sow outdoors: Mar 22 – Apr 5 |
| Carrots | Sow outdoors: Mar 22 – Apr 5 |
| Potatoes | Plant outdoors: Mar 22 – Apr 5 |
| Beans | Sow outdoors: Apr 26 – May 3 |
| Sweet corn | Sow outdoors: Apr 26 – May 3 |
| Cucumbers | Sow outdoors: Apr 26 – May 3 |
| Squash & zucchini | Sow outdoors: Apr 26 – May 3 |
| Basil | Start seeds indoors: Mar 8 – Mar 22 Transplant outdoors: Apr 26 – May 3 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 23 (8 weeks before the average first fall frost on Oct 18).
Useful for zone 5b 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 5 | Apr 19 | May 3 |
| First 32°F frost in fall is before | Oct 30 | Oct 18 | Oct 1 |
How to read it: in spring there is a 10% chance of a frost after May 3, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 1. A hard freeze (28°F) usually ends around April 9.
Hardiness zone by ZIP code in Grimes
- 50111 zone 5b
Nearby cities
- Johnston zone 5b, last frost Apr 19
- Urbandale zone 5b, last frost Apr 18
- Clive zone 5b, last frost Apr 18
- Waukee zone 5b, last frost Apr 19
- West Des Moines zone 5b, last frost Apr 18
- Ankeny zone 5b, last frost Apr 23
- Des Moines zone 5b, last frost Apr 18
- Norwalk zone 5b, last frost Apr 18
Questions
What growing zone is Grimes, IA?
Grimes is in USDA Plant Hardiness Zone 5b (average extreme winter low -15°F to -10°F), according to the USDA 2023 map.
When is the last frost in Grimes?
The average last spring frost (32°F) in Grimes is April 19. There is still a 10% chance of frost until May 3.
When can I plant tomatoes in Grimes?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 26 – May 3. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Des Moines Wsfo-Johnston, IA (USC00132209), 7.8 km (4.8 mi) from the city center, elevation 292 m, based on 24 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.