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When to Plant Cauliflower in Winneshiek County, IA

Cauliflower is a cool-season brassica that produces dense white, purple, or green heads called curds. It is more finicky than broccoli but rewards with a mild, nutty flavor.

Winneshiek County, Iowa is in USDA Zone 4b. The average last spring frost is May 3 and the first fall frost is October 6, giving you a growing season of approximately 156 days.

At an elevation of 1,360 feet, Winneshiek County receives approximately 32.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Cauliflower to ensure they mature before fall.

Winneshiek County, IA (Zone 4b) Moderate season
156 days
Last Spring Frost May 3
156 growing days
First Fall Frost October 6

Winneshiek County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (38 days to spare)
Start indoors: Mar 15 Transplant: Apr 26 🍅 Harvest: Jun 21 – Aug 23
Recommended (50%) ✓ Fits season (37 days to spare)
Start indoors: Mar 22 Transplant: May 3 🍅 Harvest: Jun 28 – Aug 30
Safe Start (90%) ✓ Fits season (34 days to spare)
Start indoors: Apr 4 Transplant: May 16 🍅 Harvest: Jul 11 – Sep 12

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.9″/week
You supply
0.7″/week
Watering frequency 2-3 times/week
Season total 1,028 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Cauliflower needs ~775 GDD — county provides 1,560 GDD Excellent fit

Cauliflower Planting Timeline โ€” Winneshiek County, IA

Cauliflower Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 โ€“ Apr 5
Transplant Outdoors May 3 May 3 โ€“ May 17
Direct Sow April 26 Apr 26 โ€“ May 17
Fall Sowing July 14 Jul 14 โ€“ Jul 28
Harvest June 28 Jun 28 โ€“ Aug 30

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Fall Sowing Harvest
August Harvest
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

High โ€” keep soil consistently moist

Days to Maturity

55โ€“100 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4b

Growing Season

156 days

Growing Tips for Winneshiek County

Start seeds indoors 6 weeks before transplanting. Blanch white varieties by tying outer leaves over the head. Provide consistent moisture and avoid temperature extremes.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Strawberries

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Frequently Asked Questions

When should I plant Cauliflower in Winneshiek County, IA?

Winneshiek County is in Zone 4b with an average last frost of May 3. Plan your Cauliflower planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Winneshiek County, IA?

Winneshiek County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is May 3 and first fall frost is October 6.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Winneshiek County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Winneshiek County, IA. Local conditions may vary. Last updated: April 2026.