Cool-Season Vegetable

When to Plant Cauliflower in Iowa

The diva of the brassica family. More temperamental than broccoli but worth the extra attention.

The Short Answer

Cauliflower are cold-tolerant and do well in Iowa's humid climate. Iowa gardeners can also plant a fall crop. Outstanding black prairie soils. Some of the richest agricultural land in the world. Minimal...

Iowa Frost Dates

Your planting dates depend on which part of Iowa you're in. Here are the frost date ranges by region:

Region Zones Last Frost (Spring) First Frost (Fall)
Northern Iowa 4b, 5a May 5 - May 20 Sep 20 - Oct 5
Central Iowa 5a, 5b Apr 25 - May 10 Oct 1 - Oct 15
Southern Iowa 5b Apr 20 - May 5 Oct 5 - Oct 20

Cauliflower Planting Schedule for Iowa

Northern Iowa (Zones 4b, 5a)

Average last frost: May 5 - May 20 · Average first frost: Sep 20 - Oct 5

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks before frost
Fall Planting
10 wks before first frost

Central Iowa (Zones 5a, 5b)

Average last frost: Apr 25 - May 10 · Average first frost: Oct 1 - Oct 15

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks before frost
Fall Planting
10 wks before first frost

Southern Iowa (Zones 5b)

Average last frost: Apr 20 - May 5 · Average first frost: Oct 5 - Oct 20

Start Seeds Indoors
6 wks before frost
Transplant Outside
2 wks before frost
Fall Planting
10 wks before first frost

Growing Cauliflower in Iowa

Cauliflower in Iowa's Climate

Cauliflower is more demanding than broccoli — it needs steady 60-70°F temperatures during heading, which your unpredictable spring weather may not provide. Fall is the better season: start indoors in mid-June, transplant in mid-July, and let the gradual autumn cool-down produce tight, clean heads. Temperature swings cause buttoning (premature tiny heads).

Soil Considerations for Iowa

Outstanding black prairie soils. Some of the richest agricultural land in the world. Minimal amendment needed.

Iowa Climate & Growing Season

Continental climate. Cold winters, warm humid summers. Good growing season with adequate rainfall.

Growing season length varies across Iowa: Northern Iowa (4b, 5a) has a last frost around May 5 - May 20, while Southern Iowa (5b) sees frost end around Apr 20 - May 5. This difference matters for cauliflower — adjust your planting dates to match your specific region.

Growing Tips

Blanch white varieties by tying outer leaves over the head when it reaches 2 inches. Temperature swings cause buttoning.

Companion Planting

Plant cauliflower alongside these companions for better growth:

Beets Celery Onions

Keep cauliflower away from:

Strawberries Tomatoes

The Bottom Line

Cauliflower can be grown successfully across Iowa, but your exact planting dates depend on which region you're in. Northern Iowa gardeners should plan around a May 5 - May 20 last frost, while those in Southern Iowa can typically plant earlier. For exact dates based on your zip code, use our free planting date finder.

Related Guides

Cauliflower Growing Guide National planting guide with all states Iowa Planting Calendar All plants for Iowa Cauliflower in Alabama Alabama planting dates Cauliflower in Alaska Alaska planting dates Cauliflower in Arizona Arizona planting dates Cauliflower in Arkansas Arkansas planting dates
Note: All dates are based on NOAA 30-year Climate Normals and represent historical averages, not predictions for any specific year. Always check your local weather forecast before planting frost-sensitive crops. Learn about our data sources.

Last reviewed: March 29, 2026

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