When to Plant Sunflower in Butler County, IA
Sunflowers are tall, cheerful annuals grown for their edible seeds and as pollinator magnets. They come in sizes from 2-foot dwarfs to 12-foot giants.
Butler County, Iowa is in USDA Zone 4b. The average last spring frost is April 30 and the first fall frost is October 7, giving you a growing season of approximately 160 days.
At an elevation of 677 feet, Butler County receives approximately 39 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Sunflower to ensure they mature before fall.
Butler County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-7.2
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
Sunflower Planting Timeline — Butler County, IA
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 26 | Feb 26 – Mar 12 |
| Transplant Outdoors | May 21 | May 21 – Jun 4 |
| Direct Sow | May 14 | May 14 – Jun 4 |
| Harvest | July 30 | Jul 30 – Sep 17 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Low — drought tolerant
Days to Maturity
70–100 days
Soil pH
6 – 7.5
USDA Zone
Zone 4b
Growing Season
160 days
Growing Tips for Butler County
Direct sow after last frost. Stake tall varieties in windy areas. Harvest seed heads when the back turns brown and seeds are plump. Dry heads upside down.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in Butler County, IA?
Butler County is in Zone 4b with an average last frost of April 30. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Butler County, IA?
Butler County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is April 30 and first fall frost is October 7.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Butler County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.
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