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When to Plant Bok Choy in Iowa County, WI

Bok choy is a Chinese cabbage variety with crisp white stalks and dark green leaves. It is a fast-growing cool-season crop ideal for stir-fries and soups.

Iowa County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 3 and the first fall frost is October 7, giving you a growing season of approximately 157 days.

At an elevation of 602 feet, Iowa County receives approximately 35.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82ยฐF, so choose short-season varieties of Bok Choy to ensure they mature before fall.

Iowa County, WI (Zone 4b) Moderate season
157 days
Last Spring Frost May 3
157 growing days
First Fall Frost October 7

Iowa County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (81 days to spare)
Start indoors: Mar 16 Transplant: Apr 27 🍅 Harvest: Jun 8 – Jul 13
Recommended (50%) ✓ Fits season (80 days to spare)
Start indoors: Mar 22 Transplant: May 3 🍅 Harvest: Jun 14 – Jul 19
Safe Start (90%) ✓ Fits season (71 days to spare)
Start indoors: Apr 9 Transplant: May 21 🍅 Harvest: Jul 2 – Aug 6

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
1.0″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 754 gal / 100 sq ft
Bok Choy needs ~575 GDD — county provides 1,805 GDD Excellent fit

Bok Choy Planting Timeline โ€” Iowa County, WI

Bok Choy 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 15 Jul 15 โ€“ Jul 29
Harvest June 14 Jun 14 โ€“ Jul 19

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 โ€”
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

40โ€“60 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 4b

Growing Season

157 days

Growing Tips for Iowa County

Direct sow in spring or fall for best results. Keep soil consistently moist. Harvest whole heads or cut outer leaves for a cut-and-come-again approach.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Level Up Your Garden

Frequently Asked Questions

When should I plant Bok Choy in Iowa County, WI?

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

What planting zone is Iowa County, WI?

Iowa County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 3 and first fall frost is October 7.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Iowa 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 Iowa County, WI. Local conditions may vary. Last updated: April 2026.