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When to Plant Napa Cabbage in Brown County, IL

Napa cabbage forms tall, barrel-shaped heads with tender, crinkled leaves and a mild, slightly sweet flavor. It is the primary cabbage used for kimchi.

Brown County, Illinois is in USDA Zone 5b. The average last spring frost is April 17 and the first fall frost is October 16, giving you a growing season of approximately 182 days.

At an elevation of 868 feet, Brown County receives approximately 36.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Napa Cabbage during the growing season.

Brown County, IL (Zone 5b) Moderate season
182 days
Last Spring Frost April 17
182 growing days
First Fall Frost October 16

Brown County Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (91 days to spare)
Start indoors: Mar 8 Transplant: Apr 12 🍅 Harvest: Jun 7 – Jul 12
Recommended (50%) ✓ Fits season (91 days to spare)
Start indoors: Mar 13 Transplant: Apr 17 🍅 Harvest: Jun 12 – Jul 17
Safe Start (90%) ✓ Fits season (91 days to spare)
Start indoors: Mar 26 Transplant: Apr 30 🍅 Harvest: Jun 25 – Jul 30

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
0.8″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 1,077 gal / 100 sq ft
Napa Cabbage needs ~942 GDD — county provides 2,639 GDD Excellent fit

Napa Cabbage Planting Timeline โ€” Brown County, IL

Napa Cabbage Planting Calendar

Activity When Date Range
Start Indoors March 13 Mar 13 โ€“ Mar 27
Transplant Outdoors April 17 Apr 17 โ€“ May 1
Direct Sow April 3 Apr 3 โ€“ Apr 24
Fall Sowing August 7 Aug 7 โ€“ Aug 21
Harvest June 12 Jun 12 โ€“ Jul 17

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

High โ€” keep soil consistently moist

Days to Maturity

55โ€“75 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 5b

Growing Season

182 days

Growing Tips for Brown County

Best grown as a fall crop. Direct sow in late summer, 60-70 days before first frost. Keep soil evenly moist. Bolt-resistant varieties are available for spring planting.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Level Up Your Garden

Frequently Asked Questions

When should I plant Napa Cabbage in Brown County, IL?

Brown County is in Zone 5b with an average last frost of April 17. Plan your Napa Cabbage planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Brown County, IL?

Brown County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 17 and first fall frost is October 16.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Brown County gardeners in Zone 5b 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 Brown County, IL. Local conditions may vary. Last updated: April 2026.