When to Plant Corn in Iowa County, IA
Corn is a warm-season grass grown for its sweet ears, which are best eaten soon after harvest. It is wind-pollinated and must be planted in blocks for good kernel fill.
Iowa County, Iowa is in USDA Zone 5a. The average last spring frost is April 25 and the first fall frost is October 11, giving you a growing season of approximately 169 days.
At an elevation of 1,014 feet, Iowa County receives approximately 40.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Corn during the growing season.
Iowa County Soil Profile
Soil Type
Silt Loam
Soil pH
6.1-7.3
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
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Corn Planting Timeline — Iowa County, IA
Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | May 2 | May 2 – May 23 |
| Harvest | July 4 | Jul 4 – Aug 29 |
Plant 1" deep · 12" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
60–100 days
Soil pH
6 – 7
USDA Zone
Zone 5a
Growing Season
169 days
Growing Tips for Iowa County
Plant in blocks of at least 4 rows rather than single rows for proper pollination. Direct sow after soil reaches 60F. Side-dress with nitrogen when plants are knee-high.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Corn in Other Locations
Frequently Asked Questions
When should I plant Corn in Iowa County, IA?
Iowa County is in Zone 5a with an average last frost of April 25. Plan your Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Iowa County, IA?
Iowa County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 25 and first fall frost is October 11.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Iowa County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.
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