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When to Plant Scallions in Iosco 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.

Iosco County, Michigan is in USDA Zone 5a. The average last spring frost is May 14 and the first fall frost is October 3, giving you a growing season of approximately 142 days.

At an elevation of 696 feet, Iosco County receives approximately 37.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88ยฐF, providing good warmth for Scallions during the growing season.

Iosco County, MI (Zone 5a) Short season
142 days
Last Spring Frost May 14
142 growing days
First Fall Frost October 3

Iosco County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (59 days to spare)
Start indoors: Apr 3 Transplant: May 8 🍅 Harvest: Jul 3 – Jul 31
Recommended (50%) ✓ Fits season (58 days to spare)
Start indoors: Apr 9 Transplant: May 14 🍅 Harvest: Jul 9 – Aug 6
Safe Start (90%) ✓ Fits season (58 days to spare)
Start indoors: Apr 23 Transplant: May 28 🍅 Harvest: Jul 23 – Aug 20

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
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Scallions needs ~960 GDD — county provides 2,272 GDD Excellent fit

Scallions Planting Timeline โ€” Iosco County, MI

Scallions Planting Calendar

Activity When Date Range
Start Indoors April 9 Apr 9 โ€“ Apr 23
Transplant Outdoors May 14 May 14 โ€“ May 28
Direct Sow April 30 Apr 30 โ€“ May 21
Fall Sowing July 25 Jul 25 โ€“ Aug 8
Harvest July 9 Jul 9 โ€“ Aug 6

Plant 0.5" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June โ€”
July Fall Sowing Harvest
August Fall Sowing Harvest
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 5a

Growing Season

142 days

Growing Tips for Iosco 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 Iosco County, MI?

Iosco County is in Zone 5a with an average last frost of May 14. Plan your Scallions planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Iosco County, MI?

Iosco County, Michigan is in USDA Hardiness Zone 5a. The average last spring frost is May 14 and first fall frost is October 3.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Iosco County gardeners in Zone 5a 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 Iosco County, MI. Local conditions may vary. Last updated: April 2026.