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When to Plant Soybeans in McLean County, IL

Soybeans (edamame) are a high-protein legume that fixes nitrogen in the soil. Fresh green soybeans harvested at the edamame stage are a nutritious snack.

McLean County, Illinois is in USDA Zone 5a. The average last spring frost is April 18 and the first fall frost is October 18, giving you a growing season of approximately 183 days.

At an elevation of 1,024 feet, McLean County receives approximately 31.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Soybeans during the growing season.

McLean County, IL (Zone 5a) Moderate season
183 days
Last Spring Frost April 18
183 growing days
First Fall Frost October 18

McLean County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (40 days to spare)
Transplant: Apr 14 🍅 Harvest: Jul 7 – Sep 1
Recommended (50%) ✓ Fits season (43 days to spare)
Transplant: Apr 18 🍅 Harvest: Jul 11 – Sep 5
Safe Start (90%) ✓ Fits season (43 days to spare)
Transplant: May 2 🍅 Harvest: Jul 25 – Sep 19

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
0.3″/week
Watering frequency Only during dry spells
Season total 436 gal / 100 sq ft
Soybeans needs ~1,450 GDD — county provides 2,653 GDD Excellent fit

Soybeans Planting Timeline โ€” McLean County, IL

Soybeans Planting Calendar

Activity When Date Range
Direct Sow April 25 Apr 25 โ€“ May 16
Harvest July 18 Jul 18 โ€“ Sep 12

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Direct Sow
May Direct Sow
June โ€”
July Harvest
August 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

80โ€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5a

Growing Season

183 days

Growing Tips for McLean County

Direct sow after soil warms to 60F. Plant in blocks rather than rows for better pollination. Harvest for edamame when pods are plump and bright green.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Level Up Your Garden

Frequently Asked Questions

When should I plant Soybeans in McLean County, IL?

McLean County is in Zone 5a with an average last frost of April 18. Plan your Soybeans planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is McLean County, IL?

McLean County, Illinois is in USDA Hardiness Zone 5a. The average last spring frost is April 18 and first fall frost is October 18.

๐ŸŒฑ

Plan Your Garden with Confidence

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