Cool-Season Vegetable

When to Plant Cauliflower in Illinois

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 Illinois's humid climate. Illinois gardeners can also plant a fall crop. Rich prairie soils — some of the most fertile in the country. Heavy clay in many areas. Well-suited...

Illinois Frost Dates

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

Region Zones Last Frost (Spring) First Frost (Fall)
Northern Illinois (Chicago) 5a, 5b Apr 25 - May 10 Oct 1 - Oct 15
Central Illinois 5b, 6a Apr 15 - May 1 Oct 5 - Oct 20
Southern Illinois 6b, 7a Apr 1 - Apr 15 Oct 15 - Nov 1

Cauliflower Planting Schedule for Illinois

Northern Illinois (Chicago) (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

Central Illinois (Zones 5b, 6a)

Average last frost: Apr 15 - May 1 · 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

Southern Illinois (Zones 6b, 7a)

Average last frost: Apr 1 - Apr 15 · Average first frost: Oct 15 - Nov 1

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

Growing Cauliflower in Illinois

Cauliflower in Illinois's Climate

Fall cauliflower is more reliable than spring in your climate. The consistent cooling trend from September through October gives cauliflower the steady conditions it demands. Spring plantings risk bolting if temperatures spike above 80°F during heading. Start with fall production before attempting spring.

Soil Considerations for Illinois

Rich prairie soils — some of the most fertile in the country. Heavy clay in many areas. Well-suited for most vegetables.

Illinois Climate & Growing Season

Continental climate with four seasons. Hot, humid summers. Cold winters. Good growing season length in central and southern regions.

Growing season length varies across Illinois: Northern Illinois (Chicago) (5a, 5b) has a last frost around Apr 25 - May 10, while Southern Illinois (6b, 7a) sees frost end around Apr 1 - Apr 15. 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 Illinois, but your exact planting dates depend on which region you're in. Northern Illinois (Chicago) gardeners should plan around a Apr 25 - May 10 last frost, while those in Southern Illinois 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 Illinois Planting Calendar All plants for Illinois 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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