When to Plant Soybeans in Marion 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.
Marion County, Illinois is in USDA Zone 6a. The average last spring frost is April 10 and the first fall frost is October 19, giving you a growing season of approximately 192 days.
At an elevation of 964 feet, Marion County receives approximately 40.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Soybeans during the growing season.
Marion County Soil Profile
Soil Type
Silt Loam
Soil pH
6.1-7
Drainage
Well Drained
Plant Planting Risk Windows
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
Soybeans Planting Timeline — Marion County, IL
Soybeans Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | April 17 | Apr 17 – May 8 |
| Harvest | July 10 | Jul 10 – Sep 4 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Direct Sow |
| May | Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
80–120 days
Soil pH
6 – 7
USDA Zone
Zone 6a
Growing Season
192 days
Growing Tips for Marion 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
Level Up Your Garden
Soybeans in Other Locations
Frequently Asked Questions
When should I plant Soybeans in Marion County, IL?
Marion County is in Zone 6a with an average last frost of April 10. Plan your Soybeans planting based on this frost date — see the calendar above for exact timing.
What planting zone is Marion County, IL?
Marion County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 10 and first fall frost is October 19.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Marion County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.
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