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When to Plant Onion in Branch 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.

Branch County, Michigan is in USDA Zone 5b. The average last spring frost is April 28 and the first fall frost is October 14, giving you a growing season of approximately 169 days.

At an elevation of 900 feet, Branch County receives approximately 39.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Onion to ensure they mature before fall.

Branch County, MI (Zone 5b) Moderate season
169 days
Last Spring Frost April 28
169 growing days
First Fall Frost October 14

Branch County Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (25 days to spare)
Start indoors: Mar 21 Transplant: Apr 25 🍅 Harvest: Jul 25 – Sep 12
Recommended (50%) ✓ Fits season (29 days to spare)
Start indoors: Mar 24 Transplant: Apr 28 🍅 Harvest: Jul 28 – Sep 15
Safe Start (90%) ✓ Fits season (23 days to spare)
Start indoors: Apr 10 Transplant: May 15 🍅 Harvest: Aug 14 – Oct 2

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 35 gal / 100 sq ft
Onion needs ~1,365 GDD — county provides 2,197 GDD Excellent fit

Onion Planting Timeline โ€” Branch County, MI

Onion Planting Calendar

Activity When Date Range
Start Indoors March 24 Mar 24 โ€“ Apr 7
Transplant Outdoors April 28 Apr 28 โ€“ May 12
Direct Sow April 14 Apr 14 โ€“ May 5
Fall Sowing August 5 Aug 5 โ€“ Aug 19
Harvest July 28 Jul 28 โ€“ Sep 15

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 Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June โ€”
July Harvest
August Fall Sowing 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 5b

Growing Season

169 days

Growing Tips for Branch 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 Branch County, MI?

Branch County is in Zone 5b with an average last frost of April 28. Plan your Onion planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Branch County, MI?

Branch County, Michigan is in USDA Hardiness Zone 5b. The average last spring frost is April 28 and first fall frost is October 14.

๐ŸŒฑ

Plan Your Garden with Confidence

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