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When to Plant Scallions in Cass 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.

Cass County, Illinois is in USDA Zone 5b. The average last spring frost is April 15 and the first fall frost is October 16, giving you a growing season of approximately 184 days.

At an elevation of 703 feet, Cass County receives approximately 31.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Scallions to ensure they mature before fall.

Cass County, IL (Zone 5b) Moderate season
184 days
Last Spring Frost April 15
184 growing days
First Fall Frost October 16

Cass County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (100 days to spare)
Start indoors: Mar 5 Transplant: Apr 9 🍅 Harvest: Jun 4 – Jul 2
Recommended (50%) ✓ Fits season (100 days to spare)
Start indoors: Mar 11 Transplant: Apr 15 🍅 Harvest: Jun 10 – Jul 8
Safe Start (90%) ✓ Fits season (98 days to spare)
Start indoors: Mar 26 Transplant: Apr 30 🍅 Harvest: Jun 25 – Jul 23

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
0.7″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 1,124 gal / 100 sq ft
Drought risk

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

Scallions needs ~735 GDD — county provides 2,254 GDD Excellent fit

Scallions Planting Timeline โ€” Cass County, IL

Scallions Planting Calendar

Activity When Date Range
Start Indoors March 11 Mar 11 โ€“ Mar 25
Transplant Outdoors April 15 Apr 15 โ€“ Apr 29
Direct Sow April 1 Apr 1 โ€“ Apr 22
Fall Sowing August 7 Aug 7 โ€“ Aug 21
Harvest June 10 Jun 10 โ€“ Jul 8

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Transplant Outdoors Direct Sow
May โ€”
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

184 days

Growing Tips for Cass 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 Cass County, IL?

Cass County is in Zone 5b with an average last frost of April 15. Plan your Scallions planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Cass County, IL?

Cass County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 15 and first fall frost is October 16.

๐ŸŒฑ

Plan Your Garden with Confidence

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