Frost dates for Winterset, IA
When the last spring frost and first fall frost usually come, and when to plant, from 30 years of NOAA weather records.
Last spring frost
April 30
typical year
Safe to plant
May 11
frost is over in 9 of 10 years
First fall frost
October 3
typical year
Growing season
157 days
frost-free, typical year
Frost watch this week
Tonight's and the next six nights' lows from the National Weather Service forecast for the station's location. Frost: 32°F or colder. Possible frost: 33–36°F, mostly in low spots on clear, still nights.
When to plant
Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.
| Crop | Start indoors | Plant outside | Fall planting |
|---|---|---|---|
| Cool-season crops | |||
| Peas | – | Apr 2 – 16 | – |
| Spinach | – | Mar 19 – Apr 9 | Aug 8 – 22 |
| Lettuce | – | Apr 2 – 23 | Aug 8 – 22 |
| Radishes | – | Apr 2 – May 14 | Aug 22 – Sep 5 |
| Onions | – | Apr 2 – 16 | – |
| Potatoes | – | Apr 9 – 23 | – |
| Carrots | – | Apr 9 – 30 | Jul 11 – 25 |
| Beets | – | Apr 2 – 16 | Jul 25 – Aug 8 |
| Kale | Feb 19 – Mar 5 | Apr 2 – 16 | Jul 25 – Aug 8 |
| Broccoli | Feb 19 – Mar 5 | Apr 16 – 30 | Jul 25 – Aug 8 |
| Cabbage | Feb 5 – 19 | Apr 2 – 16 | Jul 25 – Aug 8 |
| Garlic | – | – | Aug 22 – Sep 12 |
| Warm-season crops | |||
| Tomatoes | Mar 16 – 30 | May 11 – 25 | – |
| Peppers | Mar 9 – 23 | May 18 – Jun 1 | – |
| Cucumbers | – | May 11 – Jun 1 | – |
| Zucchini | – | May 11 – Jun 8 | – |
| Pumpkins | – | May 11 – Jun 1 | – |
| Green beans | – | May 11 – Jul 25 | – |
| Sweet corn | – | May 11 – Jun 8 | – |
| Basil | Apr 6 – 20 | May 18 – 25 | – |
Onions: from sets. Green beans: until 10 weeks before the first fall frost. Garlic: harvest next summer.
The year at a glance
Start indoors Plant outside Fall planting
The chance of frost, by date
| 1 year in 10 | Half of years | 9 years in 10 | |
|---|---|---|---|
| Spring frost after | May 11 | April 30 | April 17 |
| Fall frost before | September 20 | October 3 | October 20 |
Frost here means 32°F or colder. Read across: in 1 year in 10, spring frost carries on past the first date, which is why that date is the safe-to-plant date.
Hard freeze (28°F)
A hard freeze kills most garden plants, even hardy ones. The last one in spring usually comes around April 20 (May 3 in a late year), and the first one in fall around October 15.
Towns that use these dates
This is the nearest NOAA station with frost records for 9 towns.
Winterset, Van Meter, Earlham, De Soto, Truro, Lorimor, Patterson, East Peru, Macksburg
Where these dates come from
NOAA weather station WINTERSET 1S, IA US (USC00139132), 1991–2020 climate normals. It's the nearest station for 10 zip codes, all within 14 miles:
50069, 50070, 50072, 50149, 50155, 50218, 50222, 50257, 50261, 50273
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.