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When to Plant Scallions in Sanilac County, MI

Scallions (green onions) are mild-flavored alliums harvested for their slender green tops and white bases. They are quick-growing and perfect for succession planting.

Sanilac County, Michigan is in USDA Zone 5b. The average last spring frost is May 4 and the first fall frost is October 17, giving you a growing season of approximately 166 days.

At an elevation of 985 feet, Sanilac County receives approximately 37 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Scallions during the growing season.

Sanilac County, MI (Zone 5b) Moderate season
166 days
Last Spring Frost May 4
166 growing days
First Fall Frost October 17

Sanilac County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (80 days to spare)
Start indoors: Mar 25 Transplant: Apr 29 🍅 Harvest: Jun 24 – Jul 22
Recommended (50%) ✓ Fits season (82 days to spare)
Start indoors: Mar 30 Transplant: May 4 🍅 Harvest: Jun 29 – Jul 27
Safe Start (90%) ✓ Fits season (78 days to spare)
Start indoors: Apr 16 Transplant: May 21 🍅 Harvest: Jul 16 – Aug 13

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
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 113 gal / 100 sq ft
Drought risk

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

Scallions needs ~870 GDD — county provides 2,407 GDD Excellent fit

Scallions Planting Timeline โ€” Sanilac County, MI

Scallions Planting Calendar

Activity When Date Range
Start Indoors March 30 Mar 30 โ€“ Apr 13
Transplant Outdoors May 4 May 4 โ€“ May 18
Direct Sow April 20 Apr 20 โ€“ May 11
Fall Sowing August 8 Aug 8 โ€“ Aug 22
Harvest June 29 Jun 29 โ€“ Jul 27

Plant 0.5" deep ยท 6" apart ยท Rows 12" 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 Harvest
August Fall Sowing
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

50โ€“70 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5b

Growing Season

166 days

Growing Tips for Sanilac County

Direct sow every 3 weeks for continuous harvest. Thin to 1 inch apart or grow in clusters. Harvest when pencil-thick by pulling or cutting at soil level.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

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Frequently Asked Questions

When should I plant Scallions in Sanilac County, MI?

Sanilac County is in Zone 5b with an average last frost of May 4. Plan your Scallions planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Sanilac County, MI?

Sanilac County, Michigan is in USDA Hardiness Zone 5b. The average last spring frost is May 4 and first fall frost is October 17.

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Plan Your Garden with Confidence

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