Delta, IA frost dates
Last spring frostApr 24median date
First fall frostOct 15median date
Growing season174 daysfrost-free
Hardiness zone5bZone 5b
How Delta compares
- In 8 years out of 10, the last spring frost in Delta falls between April 9 and May 9, a 30-day window. The first fall frost falls between September 30 and October 27.
- The median last frost is 4 days earlier than the Iowa median of Apr 28.
- Its 174-day growing season is longer than 78% of the 934 Iowa places with a regular frost season (state median 165 days).
- The last frost is 7 days earlier than the zone 5b median of May 1. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 5b chart.
- The weather station records an average of 142 nights a year at or below 32°F.
- Compared with Iowa City, IA, 74 km away, the last frost here is 3 days later than there and the growing season is 6 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 9 |
| 50% (median) | April 24 |
| 10% (safe for tender plants) | May 9 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 30 |
| 50% (median) | October 15 |
| 90% (late) | October 27 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Delta, IA
Delta, IA frost dates — last frost Apr 24, first frost Oct 15, zone 5b. whenisthelastfrost.com
Crop
JFMAMJJASOND
Start indoors: Jan 30 to Feb 13Transplant outside: Mar 27 to Apr 10
Start indoors: Feb 13 to Feb 27Transplant outside: May 8 to May 22
Start indoors: Feb 13 to Feb 27Transplant outside: May 8 to May 22
Start indoors: Feb 27 to Mar 13Transplant outside: May 1 to May 15
Start indoors: Feb 27 to Mar 13Transplant outside: Apr 3 to Apr 17Sow outdoors: Mar 27 to May 1Plant for fall: Aug 20 to Sep 17
Start indoors: Feb 27 to Mar 13Transplant outside: Mar 27 to Apr 10Sow outdoors: Mar 27 to Apr 10Plant for fall: Aug 6 to Aug 27
Start indoors: Feb 27 to Mar 13Transplant outside: Apr 10 to Apr 24Plant for fall: Jul 9 to Jul 30
Start indoors: Feb 27 to Mar 13Transplant outside: Apr 3 to Apr 17Plant for fall: Jul 9 to Jul 30
Start indoors: Feb 27 to Mar 13Transplant outside: Apr 10 to Apr 24Plant for fall: Jul 9 to Jul 30
Start indoors: Mar 13 to Mar 27Transplant outside: May 15 to May 29Sow outdoors: May 15 to May 29
Start indoors: Mar 13 to Mar 27Transplant outside: May 1 to May 15
Sow outdoors: Mar 13 to Apr 3Plant for fall: Jul 23 to Aug 13
Sow outdoors: Mar 13 to Apr 3Plant for fall: Aug 20 to Sep 10
Sow outdoors: Mar 20 to May 1Plant for fall: Sep 3 to Sep 24
Start indoors: Mar 27 to Apr 3Transplant outside: May 8 to May 15Sow outdoors: May 1 to May 15Plant for fall: Jul 30 to Aug 13
Start indoors: Mar 27 to Apr 3Sow outdoors: May 1 to May 15Plant for fall: Aug 6 to Aug 20
Start indoors: Mar 27 to Apr 3Sow outdoors: May 1 to May 15
Start indoors: Mar 27 to Apr 3Transplant outside: May 8 to May 22
Sow outdoors: Apr 3 to May 1Plant for fall: Jul 23 to Aug 6
Sow outdoors: Apr 3 to May 1Plant for fall: Aug 6 to Aug 20
Sow outdoors: Apr 3 to Apr 24
Sow outdoors: Apr 10 to May 8Plant for fall: Aug 6 to Aug 20
Sow outdoors: Apr 10 to May 1Plant for fall: Aug 20 to Sep 10
Sow outdoors: May 1 to May 22Plant for fall: Jul 30 to Aug 13
Sow outdoors: May 1 to May 15
Transplant outside: May 8 to May 29
Plant for fall: Oct 1 to Nov 5
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Delta, IA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 30 – Feb 13 | Mar 27 – Apr 10 | — | — |
| Peppers | Feb 13 – Feb 27 | May 8 – May 22 | — | — |
| Eggplant | Feb 13 – Feb 27 | May 8 – May 22 | — | — |
| Tomatoes | Feb 27 – Mar 13 | May 1 – May 15 | — | — |
| Lettuce | Feb 27 – Mar 13 | Apr 3 – Apr 17 | Mar 27 – May 1 | Aug 20 – Sep 17 |
| Kale | Feb 27 – Mar 13 | Mar 27 – Apr 10 | Mar 27 – Apr 10 | Aug 6 – Aug 27 |
| Broccoli | Feb 27 – Mar 13 | Apr 10 – Apr 24 | — | Jul 9 – Jul 30 |
| Cabbage | Feb 27 – Mar 13 | Apr 3 – Apr 17 | — | Jul 9 – Jul 30 |
| Cauliflower | Feb 27 – Mar 13 | Apr 10 – Apr 24 | — | Jul 9 – Jul 30 |
| Okra | Mar 13 – Mar 27 | May 15 – May 29 | May 15 – May 29 | — |
| Basil | Mar 13 – Mar 27 | May 1 – May 15 | — | — |
| Peas | — | — | Mar 13 – Apr 3 | Jul 23 – Aug 13 |
| Spinach | — | — | Mar 13 – Apr 3 | Aug 20 – Sep 10 |
| Radishes | — | — | Mar 20 – May 1 | Sep 3 – Sep 24 |
| Cucumbers | Mar 27 – Apr 3 | May 8 – May 15 | May 1 – May 15 | Jul 30 – Aug 13 |
| Zucchini & Summer Squash | Mar 27 – Apr 3 | — | May 1 – May 15 | Aug 6 – Aug 20 |
| Winter Squash & Pumpkins | Mar 27 – Apr 3 | — | May 1 – May 15 | — |
| Melons & Watermelon | Mar 27 – Apr 3 | May 8 – May 22 | — | — |
| Carrots | — | — | Apr 3 – May 1 | Jul 23 – Aug 6 |
| Beets | — | — | Apr 3 – May 1 | Aug 6 – Aug 20 |
| Potatoes | — | — | Apr 3 – Apr 24 | — |
| Swiss Chard | — | — | Apr 10 – May 8 | Aug 6 – Aug 20 |
| Cilantro | — | — | Apr 10 – May 1 | Aug 20 – Sep 10 |
| Green Beans | — | — | May 1 – May 22 | Jul 30 – Aug 13 |
| Sweet Corn | — | — | May 1 – May 15 | — |
| Sweet Potatoes | — | May 8 – May 29 | — | — |
| Garlic | — | — | — | Oct 1 – Nov 5 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Sigourney, IA weather station, 9 km away (elevation 732 ft (223 m)).
Frost dates near Delta
- What Cheer Apr 24 · Oct 15
- Sigourney Apr 24 · Oct 15
- Rose Hill Apr 21 · Oct 16
- Hayesville Apr 24 · Oct 15
- Fremont Apr 23 · Oct 14
- Martinsburg Apr 24 · Oct 15
- Hedrick Apr 23 · Oct 14
- Thornburg Apr 24 · Oct 15
- Keswick Apr 24 · Oct 15
- Cedar Apr 23 · Oct 14
Frequently asked questions
When is the last frost in Delta, IA?
The median last spring frost in Delta, IA is April 24. There is still about a 10% chance of frost after May 9, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Delta, IA?
The median first fall frost is October 15, with about a 10% chance of frost before September 30.
How long is the growing season in Delta, IA?
About 174 days between the median last spring frost and first fall frost.
What planting zone is Delta, IA?
Delta, IA is in USDA hardiness zone 5b.