Denmark, IA frost dates
Last spring frostApr 12median date
First fall frostOct 25median date
Growing season196 daysfrost-free
Hardiness zone6aZone 6a
How Denmark compares
- In 8 years out of 10, the last spring frost in Denmark falls between April 1 and April 26, a 25-day window. The first fall frost falls between October 11 and November 6.
- The median last frost is 16 days earlier than the Iowa median of Apr 28.
- Its 196-day growing season is among the longest of the 934 Iowa places with a regular frost season.
- The last frost is 17 days earlier than the zone 6a median of Apr 29. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6a chart.
- The weather station records an average of 110 nights a year at or below 32°F.
- Compared with Iowa City, IA, 101 km away, the last frost here is 9 days earlier than there and the growing season is 16 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 1 |
| 50% (median) | April 12 |
| 10% (safe for tender plants) | April 26 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | October 11 |
| 50% (median) | October 25 |
| 90% (late) | November 6 |
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 Denmark, IA
Denmark, IA frost dates — last frost Apr 12, first frost Oct 25, zone 6a. whenisthelastfrost.com
Crop
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Start indoors: Jan 18 to Feb 1Transplant outside: Mar 15 to Mar 29
Start indoors: Feb 1 to Feb 15Transplant outside: Apr 26 to May 10
Start indoors: Feb 1 to Feb 15Transplant outside: Apr 26 to May 10
Start indoors: Feb 15 to Mar 1Transplant outside: Apr 19 to May 3
Start indoors: Feb 15 to Mar 1Transplant outside: Mar 22 to Apr 5Sow outdoors: Mar 15 to Apr 19Plant for fall: Aug 30 to Sep 27
Start indoors: Feb 15 to Mar 1Transplant outside: Mar 15 to Mar 29Sow outdoors: Mar 15 to Mar 29Plant for fall: Aug 16 to Sep 6
Start indoors: Feb 15 to Mar 1Transplant outside: Mar 29 to Apr 12Plant for fall: Jul 19 to Aug 9
Start indoors: Feb 15 to Mar 1Transplant outside: Mar 22 to Apr 5Plant for fall: Jul 19 to Aug 9
Start indoors: Feb 15 to Mar 1Transplant outside: Mar 29 to Apr 12Plant for fall: Jul 19 to Aug 9
Start indoors: Mar 1 to Mar 15Transplant outside: May 3 to May 17Sow outdoors: May 3 to May 17
Start indoors: Mar 1 to Mar 15Transplant outside: Apr 19 to May 3
Sow outdoors: Mar 1 to Mar 22Plant for fall: Aug 2 to Aug 23
Sow outdoors: Mar 1 to Mar 22Plant for fall: Aug 30 to Sep 20
Sow outdoors: Mar 8 to Apr 19Plant for fall: Sep 13 to Oct 4
Start indoors: Mar 15 to Mar 22Transplant outside: Apr 26 to May 3Sow outdoors: Apr 19 to May 3Plant for fall: Aug 9 to Aug 23
Start indoors: Mar 15 to Mar 22Sow outdoors: Apr 19 to May 3Plant for fall: Aug 16 to Aug 30
Start indoors: Mar 15 to Mar 22Sow outdoors: Apr 19 to May 3
Start indoors: Mar 15 to Mar 22Transplant outside: Apr 26 to May 10
Sow outdoors: Mar 22 to Apr 19Plant for fall: Aug 2 to Aug 16
Sow outdoors: Mar 22 to Apr 19Plant for fall: Aug 16 to Aug 30
Sow outdoors: Mar 22 to Apr 12
Sow outdoors: Mar 29 to Apr 26Plant for fall: Aug 16 to Aug 30
Sow outdoors: Mar 29 to Apr 19Plant for fall: Aug 30 to Sep 20
Sow outdoors: Apr 19 to May 10Plant for fall: Aug 9 to Aug 23
Sow outdoors: Apr 19 to May 3
Transplant outside: Apr 26 to May 17
Plant for fall: Oct 11 to Nov 15
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Denmark, IA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Jan 18 – Feb 1 | Mar 15 – Mar 29 | — | — |
| Peppers | Feb 1 – Feb 15 | Apr 26 – May 10 | — | — |
| Eggplant | Feb 1 – Feb 15 | Apr 26 – May 10 | — | — |
| Tomatoes | Feb 15 – Mar 1 | Apr 19 – May 3 | — | — |
| Lettuce | Feb 15 – Mar 1 | Mar 22 – Apr 5 | Mar 15 – Apr 19 | Aug 30 – Sep 27 |
| Kale | Feb 15 – Mar 1 | Mar 15 – Mar 29 | Mar 15 – Mar 29 | Aug 16 – Sep 6 |
| Broccoli | Feb 15 – Mar 1 | Mar 29 – Apr 12 | — | Jul 19 – Aug 9 |
| Cabbage | Feb 15 – Mar 1 | Mar 22 – Apr 5 | — | Jul 19 – Aug 9 |
| Cauliflower | Feb 15 – Mar 1 | Mar 29 – Apr 12 | — | Jul 19 – Aug 9 |
| Okra | Mar 1 – Mar 15 | May 3 – May 17 | May 3 – May 17 | — |
| Basil | Mar 1 – Mar 15 | Apr 19 – May 3 | — | — |
| Peas | — | — | Mar 1 – Mar 22 | Aug 2 – Aug 23 |
| Spinach | — | — | Mar 1 – Mar 22 | Aug 30 – Sep 20 |
| Radishes | — | — | Mar 8 – Apr 19 | Sep 13 – Oct 4 |
| Cucumbers | Mar 15 – Mar 22 | Apr 26 – May 3 | Apr 19 – May 3 | Aug 9 – Aug 23 |
| Zucchini & Summer Squash | Mar 15 – Mar 22 | — | Apr 19 – May 3 | Aug 16 – Aug 30 |
| Winter Squash & Pumpkins | Mar 15 – Mar 22 | — | Apr 19 – May 3 | — |
| Melons & Watermelon | Mar 15 – Mar 22 | Apr 26 – May 10 | — | — |
| Carrots | — | — | Mar 22 – Apr 19 | Aug 2 – Aug 16 |
| Beets | — | — | Mar 22 – Apr 19 | Aug 16 – Aug 30 |
| Potatoes | — | — | Mar 22 – Apr 12 | — |
| Swiss Chard | — | — | Mar 29 – Apr 26 | Aug 16 – Aug 30 |
| Cilantro | — | — | Mar 29 – Apr 19 | Aug 30 – Sep 20 |
| Green Beans | — | — | Apr 19 – May 10 | Aug 9 – Aug 23 |
| Sweet Corn | — | — | Apr 19 – May 3 | — |
| Sweet Potatoes | — | Apr 26 – May 17 | — | — |
| Garlic | — | — | — | Oct 11 – Nov 15 |
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 Ft Madison, IA weather station, 13 km away (elevation 531 ft (162 m)).
Frost dates near Denmark
- West Point Apr 17 · Oct 22
- Wever Apr 18 · Oct 20
- Middletown Apr 15 · Oct 20
- Fort Madison Apr 12 · Oct 25
- Danville Apr 15 · Oct 20
- Saint Paul Apr 17 · Oct 22
- West Burlington Apr 15 · Oct 20
- Pilot Grove Apr 17 · Oct 22
- Burlington Apr 15 · Oct 20
- New London Apr 30 · Oct 10
Frequently asked questions
When is the last frost in Denmark, IA?
The median last spring frost in Denmark, IA is April 12. There is still about a 10% chance of frost after April 26, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Denmark, IA?
The median first fall frost is October 25, with about a 10% chance of frost before October 11.
How long is the growing season in Denmark, IA?
About 196 days between the median last spring frost and first fall frost.
What planting zone is Denmark, IA?
Denmark, IA is in USDA hardiness zone 6a.