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When to Plant Onion in Shawano County, WI

Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.

Shawano County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 8 and the first fall frost is October 5, giving you a growing season of approximately 150 days.

At an elevation of 955 feet, Shawano County receives approximately 34.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Onion to ensure they mature before fall.

Shawano County, WI (Zone 4b) Moderate season
150 days
Last Spring Frost May 8
150 growing days
First Fall Frost October 5

Shawano County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (15 days to spare)
Start indoors: Mar 18 Transplant: Apr 29 🍅 Harvest: Jul 29 – Sep 16
Recommended (50%) ✓ Fits season (10 days to spare)
Start indoors: Mar 27 Transplant: May 8 🍅 Harvest: Aug 7 – Sep 25
Safe Start (90%) ✓ Fits season (12 days to spare)
Start indoors: Apr 9 Transplant: May 21 🍅 Harvest: Aug 20 – Oct 8

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
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 50 gal / 100 sq ft
Drought risk

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

Onion needs ~1,050 GDD — county provides 1,500 GDD Excellent fit

Onion Planting Timeline โ€” Shawano County, WI

Onion Planting Calendar

Activity When Date Range
Start Indoors March 27 Mar 27 โ€“ Apr 10
Transplant Outdoors May 8 May 8 โ€“ May 22
Direct Sow May 1 May 1 โ€“ May 22
Fall Sowing July 13 Jul 13 โ€“ Jul 27
Harvest August 7 Aug 7 โ€“ Sep 25

Plant 1" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4b

Growing Season

150 days

Growing Tips for Shawano County

Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans
  • Asparagus

Level Up Your Garden

Frequently Asked Questions

When should I plant Onion in Shawano County, WI?

Shawano County is in Zone 4b with an average last frost of May 8. Plan your Onion planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Shawano County, WI?

Shawano County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 8 and first fall frost is October 5.

๐ŸŒฑ

Plan Your Garden with Confidence

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

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

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