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When to Plant Onion in Schoolcraft County, MI

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.

Schoolcraft County, Michigan is in USDA Zone 4b. The average last spring frost is May 14 and the first fall frost is October 12, giving you a growing season of approximately 151 days.

At an elevation of 1,121 feet, Schoolcraft County receives approximately 37.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82ยฐF, so choose short-season varieties of Onion to ensure they mature before fall.

Schoolcraft County, MI (Zone 4b) Moderate season
151 days
Last Spring Frost May 14
151 growing days
First Fall Frost October 12

Schoolcraft County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (11 days to spare)
Start indoors: Mar 26 Transplant: May 7 🍅 Harvest: Aug 6 – Sep 24
Recommended (50%) ✓ Fits season (11 days to spare)
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Aug 13 – Oct 1
Safe Start (90%) ✓ Fits season (15 days to spare)
Start indoors: Apr 15 Transplant: May 27 🍅 Harvest: Aug 26 – Oct 14

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
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Onion needs ~1,208 GDD — county provides 1,736 GDD Excellent fit

Onion Planting Timeline โ€” Schoolcraft County, MI

Onion Planting Calendar

Activity When Date Range
Start Indoors April 2 Apr 2 โ€“ Apr 16
Transplant Outdoors May 14 May 14 โ€“ May 28
Direct Sow May 7 May 7 โ€“ May 28
Fall Sowing July 20 Jul 20 โ€“ Aug 3
Harvest August 13 Aug 13 โ€“ Oct 1

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

Month-by-Month Timeline

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

151 days

Growing Tips for Schoolcraft 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 Schoolcraft County, MI?

Schoolcraft County is in Zone 4b with an average last frost of May 14. Plan your Onion planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Schoolcraft County, MI?

Schoolcraft County, Michigan is in USDA Hardiness Zone 4b. The average last spring frost is May 14 and first fall frost is October 12.

๐ŸŒฑ

Plan Your Garden with Confidence

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