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When to Plant Scallions in Winnebago County, IL

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.

Winnebago County, Illinois is in USDA Zone 5a. The average last spring frost is April 26 and the first fall frost is October 12, giving you a growing season of approximately 169 days.

At an elevation of 1,318 feet, Winnebago County receives approximately 38.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87ยฐF, providing good warmth for Scallions during the growing season.

Winnebago County, IL (Zone 5a) Moderate season
169 days
Last Spring Frost April 26
169 growing days
First Fall Frost October 12

Winnebago County Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (85 days to spare)
Start indoors: Mar 17 Transplant: Apr 21 🍅 Harvest: Jun 16 – Jul 14
Recommended (50%) ✓ Fits season (85 days to spare)
Start indoors: Mar 22 Transplant: Apr 26 🍅 Harvest: Jun 21 – Jul 19
Safe Start (90%) ✓ Fits season (86 days to spare)
Start indoors: Apr 5 Transplant: May 10 🍅 Harvest: Jul 5 – Aug 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
0.1″/week
Watering frequency Only during dry spells
Season total 80 gal / 100 sq ft
Scallions needs ~915 GDD — county provides 2,577 GDD Excellent fit

Scallions Planting Timeline โ€” Winnebago County, IL

Scallions Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 โ€“ Apr 5
Transplant Outdoors April 26 Apr 26 โ€“ May 10
Direct Sow April 12 Apr 12 โ€“ May 3
Fall Sowing August 3 Aug 3 โ€“ Aug 17
Harvest June 21 Jun 21 โ€“ Jul 19

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 Transplant Outdoors 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 5a

Growing Season

169 days

Growing Tips for Winnebago 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 Winnebago County, IL?

Winnebago County is in Zone 5a with an average last frost of April 26. Plan your Scallions planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Winnebago County, IL?

Winnebago County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 26 and first fall frost is October 12.

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Plan Your Garden with Confidence

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