When to Plant Corn in Sully County, SD
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.
Sully County, South Dakota is in USDA Zone 4a. The average last spring frost is May 11 and the first fall frost is October 3, giving you a growing season of approximately 145 days.
At an elevation of 650 feet, Sully County receives approximately 26.8 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Corn to ensure they mature before fall.
Sully County Soil Profile
Soil Type
Loam
Soil pH
6.7-7.8
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 — Sully County, SD
Corn Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | May 25 | May 25 – Jun 15 |
| Harvest | July 27 | Jul 27 – Sep 21 |
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 4a
Growing Season
145 days
Growing Tips for Sully 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 Sully County, SD?
Sully County is in Zone 4a with an average last frost of May 11. Plan your Corn planting based on this frost date — see the calendar above for exact timing.
What planting zone is Sully County, SD?
Sully County, South Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 11 and first fall frost is October 3.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Sully County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.
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