Iowa vegetable planting calendar 2027: frost dates and when to plant
In Iowa, the average last spring frost is April 18 in Des Moines (NOAA 1991-2020 normals). Below are planting dates for Des Moines for 27 common vegetables and herbs, worked out the way the Rowtime app does it: NOAA's average frost dates for the nearest weather station, with the planting rules of state extension guides. Dates are for the 2027 season.
Rowtime: Garden Planner works these dates out for your own ZIP code in Iowa, shows where each one comes from, and recalculates when a planting slips. Get Rowtime on the App Store.
Dates are estimates. Check your local extension office before you plant, and use your own frost records if you have them. Dates shift by a week or more within a state, so pick the city closest to your conditions.
Des Moines
When to plant tomatoes in Des Moines?
In Des Moines, Iowa, the average last spring frost is April 18 and the average first fall frost is October 20 (NOAA 1991-2020 normals, DES MOINES INTL AP station, 6.2 km from ZIP 50309). For tomatoes, start seeds indoors March 23 to May 29 and plant out seedlings May 2 to July 22, following University of Maryland Extension (Home & Garden Information Center) and Purdue University Extension. Dates are for the 2027 season; sources last checked October 24, 2026.
Frost dates for Des Moines (50309)
- Last spring frost: Apr 18 on average, May 2 for a 10% risk of a later frost.
- First fall frost: Oct 20 on average, Oct 4 for a 10% risk of an earlier frost.
- USDA hardiness zone 5b (PRISM 2023 listing).
| Crop | When |
|---|---|
| Beet | Sow outdoors: Apr 4 to Apr 18 Sow outdoors for fall: Aug 9 to Sep 6 |
| Broccoli | Start seeds indoors: Mar 2 to Apr 8 Plant out seedlings: Mar 21 to Apr 4 Plant out seedlings for fall: Aug 9 to Sep 6 |
| Cabbage | Start seeds indoors: Feb 23 to Mar 22 Plant out seedlings: Mar 21 to Apr 4 Plant out seedlings for fall: Aug 9 to Sep 6 |
| Carrot | Sow outdoors: Apr 4 to Apr 18 |
| Cauliflower | Start seeds indoors: Mar 9 to Apr 8 Plant out seedlings: Apr 4 to Apr 18 Plant out seedlings for fall: Jun 20 to Jul 20 |
| Cucumber | Sow outdoors: May 16 to Aug 11 |
| Eggplant | Start seeds indoors: Apr 9 to May 8 Plant out seedlings: May 16 to Jul 22 |
| Green onion | Plant onion sets: Mar 21 to Apr 4 Plant out seedlings for fall: Aug 9 to Sep 6 |
| Kale | Sow outdoors: Mar 21 to Apr 4 Sow outdoors for fall: Aug 9 to Sep 6 |
| Lettuce | Sow outdoors: Apr 4 to Apr 18 Sow outdoors for fall: Aug 9 to Sep 6 |
| Melon and watermelon | Sow outdoors: May 16 to Jul 12 |
| Okra | Plant out seedlings: May 16 to Aug 16 |
| Onion | Plant onion sets: Mar 21 to Apr 4 |
| Pea | Sow outdoors: Mar 21 to Apr 4 |
| Pepper | Start seeds indoors: Mar 23 to Apr 22 Plant out seedlings: May 16 to Jul 22 |
| Potato | Plant seed potatoes: Mar 21 to Apr 4 |
| Snap bean | Sow outdoors: May 2 to Aug 21 |
| Spinach | Sow outdoors: Mar 21 to Apr 4 Sow outdoors for fall: Aug 9 to Sep 6 |
| Summer squash | Sow outdoors: May 16 to Aug 21 |
| Sweet corn | Sow outdoors: May 2 to Jul 22 |
| Sweet potato | Sprout slips indoors: Apr 23 to May 22 Plant out slips: May 16 to Jun 12 |
| Tomato | Start seeds indoors: Mar 23 to May 29 Plant out seedlings: May 2 to Jul 22 |
| Winter squash and pumpkin | Sow outdoors: May 16 to Jul 12 |
| Basil | Plant outdoors: May 22 to Aug 21 |
| Cilantro | Sow outdoors: Feb 22 to Apr 21 Sow outdoors for fall: Aug 28 to Sep 11 |
| Dill | Sow outdoors: Apr 6 to Apr 21 Sow outdoors for fall: Jul 13 to Aug 27 |
| Parsley | Sow outdoors: Apr 9 to May 8 Plant outdoors for fall: Jul 13 to Sep 11 |
Sources
Planting rules, in the order Rowtime tries them here:
- Purdue University Extension, Indiana Vegetable Planting Calendar (HO-186-W). Checked October 20, 2026.
- University of Maryland Extension (Home & Garden Information Center), Vegetable Planting Calendar for Central Maryland. Checked October 24, 2026.
- NC State Extension, Central North Carolina Planting Calendar for Annual Vegetables, Fruits, and Herbs (AG-756-01). Checked October 21, 2026.
Frost dates, locations and zones:
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991-2020 annual/seasonal (freeze probabilities).
- U.S. Census Bureau, 2025 Gazetteer Files: ZIP Code Tabulation Areas.
- PRISM Group, Oregon State University / USDA ARS, 2023 USDA Plant Hardiness Zone Map ZIP code listings. PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed 20 Oct 2026.
How the dates are worked out: a guide's rule such as "two weeks after the last frost" is applied to the station's NOAA date. Purdue's dates are 10% dates, so they are counted from the station's 10% date. When a guide gives no last date, the window closes early enough for the crop's longest days to harvest before the first fall frost. When a guide gives no first date for a fall planting, no fall window is shown. "Season too short" means the guide's window would close before it opens at this station's frost dates.
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