Osage, IA frost dates
Last spring frostApr 30median date
First fall frostOct 9median date
Growing season162 daysfrost-free
Hardiness zone5aZone 5a
How Osage compares
- In 8 years out of 10, the last spring frost in Osage falls between April 14 and May 12, a 28-day window. The first fall frost falls between September 25 and October 21.
- The median last frost is 2 days later than the Iowa median of Apr 28.
- Its 162-day growing season is longer than 31% of the 934 Iowa places with a regular frost season (state median 165 days).
- The last frost is typical for zone 5a, where the median is May 3.
- The weather station records an average of 156 nights a year at or below 32°F.
- Compared with Rochester, MN, 87 km away, the last frost here is the same as there and the growing season is 3 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 14 |
| 50% (median) | April 30 |
| 10% (safe for tender plants) | May 12 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 25 |
| 50% (median) | October 9 |
| 90% (late) | October 21 |
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 Osage, IA
Osage, IA frost dates — last frost Apr 30, first frost Oct 9, zone 5a. whenisthelastfrost.com
Crop
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Start indoors: Feb 5 to Feb 19Transplant outside: Apr 2 to Apr 16
Start indoors: Feb 19 to Mar 5Transplant outside: May 14 to May 28
Start indoors: Feb 19 to Mar 5Transplant outside: May 14 to May 28
Start indoors: Mar 5 to Mar 19Transplant outside: May 7 to May 21
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 9 to Apr 23Sow outdoors: Apr 2 to May 7Plant for fall: Aug 14 to Sep 11
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 2 to Apr 16Sow outdoors: Apr 2 to Apr 16Plant for fall: Jul 31 to Aug 21
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 16 to Apr 30Plant for fall: Jul 3 to Jul 24
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 9 to Apr 23Plant for fall: Jul 3 to Jul 24
Start indoors: Mar 5 to Mar 19Transplant outside: Apr 16 to Apr 30Plant for fall: Jul 3 to Jul 24
Start indoors: Mar 19 to Apr 2Transplant outside: May 21 to Jun 4Sow outdoors: May 21 to Jun 4
Start indoors: Mar 19 to Apr 2Transplant outside: May 7 to May 21
Sow outdoors: Mar 19 to Apr 9Plant for fall: Jul 17 to Aug 7
Sow outdoors: Mar 19 to Apr 9Plant for fall: Aug 14 to Sep 4
Sow outdoors: Mar 26 to May 7Plant for fall: Aug 28 to Sep 18
Start indoors: Apr 2 to Apr 9Transplant outside: May 14 to May 21Sow outdoors: May 7 to May 21Plant for fall: Jul 24 to Aug 7
Start indoors: Apr 2 to Apr 9Sow outdoors: May 7 to May 21Plant for fall: Jul 31 to Aug 14
Start indoors: Apr 2 to Apr 9Sow outdoors: May 7 to May 21
Start indoors: Apr 2 to Apr 9Transplant outside: May 14 to May 28
Sow outdoors: Apr 9 to May 7Plant for fall: Jul 17 to Jul 31
Sow outdoors: Apr 9 to May 7Plant for fall: Jul 31 to Aug 14
Sow outdoors: Apr 9 to Apr 30
Sow outdoors: Apr 16 to May 14Plant for fall: Jul 31 to Aug 14
Sow outdoors: Apr 16 to May 7Plant for fall: Aug 14 to Sep 4
Sow outdoors: May 7 to May 28Plant for fall: Jul 24 to Aug 7
Sow outdoors: May 7 to May 21
Transplant outside: May 14 to Jun 4
Plant for fall: Sep 25 to Oct 30
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Osage, IA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 5 – Feb 19 | Apr 2 – Apr 16 | — | — |
| Peppers | Feb 19 – Mar 5 | May 14 – May 28 | — | — |
| Eggplant | Feb 19 – Mar 5 | May 14 – May 28 | — | — |
| Tomatoes | Mar 5 – Mar 19 | May 7 – May 21 | — | — |
| Lettuce | Mar 5 – Mar 19 | Apr 9 – Apr 23 | Apr 2 – May 7 | Aug 14 – Sep 11 |
| Kale | Mar 5 – Mar 19 | Apr 2 – Apr 16 | Apr 2 – Apr 16 | Jul 31 – Aug 21 |
| Broccoli | Mar 5 – Mar 19 | Apr 16 – Apr 30 | — | Jul 3 – Jul 24 |
| Cabbage | Mar 5 – Mar 19 | Apr 9 – Apr 23 | — | Jul 3 – Jul 24 |
| Cauliflower | Mar 5 – Mar 19 | Apr 16 – Apr 30 | — | Jul 3 – Jul 24 |
| Okra | Mar 19 – Apr 2 | May 21 – Jun 4 | May 21 – Jun 4 | — |
| Basil | Mar 19 – Apr 2 | May 7 – May 21 | — | — |
| Peas | — | — | Mar 19 – Apr 9 | Jul 17 – Aug 7 |
| Spinach | — | — | Mar 19 – Apr 9 | Aug 14 – Sep 4 |
| Radishes | — | — | Mar 26 – May 7 | Aug 28 – Sep 18 |
| Cucumbers | Apr 2 – Apr 9 | May 14 – May 21 | May 7 – May 21 | Jul 24 – Aug 7 |
| Zucchini & Summer Squash | Apr 2 – Apr 9 | — | May 7 – May 21 | Jul 31 – Aug 14 |
| Winter Squash & Pumpkins | Apr 2 – Apr 9 | — | May 7 – May 21 | — |
| Melons & Watermelon | Apr 2 – Apr 9 | May 14 – May 28 | — | — |
| Carrots | — | — | Apr 9 – May 7 | Jul 17 – Jul 31 |
| Beets | — | — | Apr 9 – May 7 | Jul 31 – Aug 14 |
| Potatoes | — | — | Apr 9 – Apr 30 | — |
| Swiss Chard | — | — | Apr 16 – May 14 | Jul 31 – Aug 14 |
| Cilantro | — | — | Apr 16 – May 7 | Aug 14 – Sep 4 |
| Green Beans | — | — | May 7 – May 28 | Jul 24 – Aug 7 |
| Sweet Corn | — | — | May 7 – May 21 | — |
| Sweet Potatoes | — | May 14 – Jun 4 | — | — |
| Garlic | — | — | — | Sep 25 – Oct 30 |
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 Osage, IA weather station, about 1 km away (elevation 1,171 ft (357 m)).
Frost dates near Osage
- Toeterville Apr 30 · Oct 9
- Orchard Apr 30 · Oct 9
- Little Cedar Apr 30 · Oct 9
- Saint Ansgar Apr 30 · Oct 9
- Rudd Apr 30 · Oct 9
- Floyd Apr 30 · Oct 6
- Stacyville Apr 30 · Oct 9
- Nora Springs Apr 29 · Oct 7
- Carpenter May 4 · Oct 4
- Grafton May 4 · Oct 4
Frequently asked questions
When is the last frost in Osage, IA?
The median last spring frost in Osage, IA is April 30. There is still about a 10% chance of frost after May 12, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Osage, IA?
The median first fall frost is October 9, with about a 10% chance of frost before September 25.
How long is the growing season in Osage, IA?
About 162 days between the median last spring frost and first fall frost.
What planting zone is Osage, IA?
Osage, IA is in USDA hardiness zone 5a.