When to Plant Corn in Black Hawk 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.
Black Hawk County, Iowa is in USDA Zone 4b. The average last spring frost is April 29 and the first fall frost is October 7, giving you a growing season of approximately 161 days.
At an elevation of 1,380 feet, Black Hawk County receives approximately 38.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Corn to ensure they mature before fall.
Black Hawk County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-7.1
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 — Black Hawk County, IA
Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | May 13 | May 13 – Jun 3 |
| Harvest | July 15 | Jul 15 – Sep 9 |
Plant 1" deep · 12" apart · Rows 36" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Direct Sow |
| June | Direct Sow |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| 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 4b
Growing Season
161 days
Growing Tips for Black Hawk 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 Black Hawk County, IA?
Black Hawk County is in Zone 4b with an average last frost of April 29. Plan your Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Black Hawk County, IA?
Black Hawk County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is April 29 and first fall frost is October 7.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Black Hawk County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.
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