When to Plant Sunflower in Allen County, OH
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.
Allen County, Ohio is in USDA Zone 5b. The average last spring frost is April 23 and the first fall frost is October 22, giving you a growing season of approximately 182 days.
At an elevation of 593 feet, Allen County receives approximately 40.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Sunflower during the growing season.
Allen County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-7.3
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
Sunflower Planting Timeline — Allen County, OH
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 26 | Feb 26 – Mar 12 |
| Transplant Outdoors | May 7 | May 7 – May 21 |
| Direct Sow | April 30 | Apr 30 – May 21 |
| Harvest | July 16 | Jul 16 – Sep 3 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| 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 5b
Growing Season
182 days
Growing Tips for Allen 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 Allen County, OH?
Allen County is in Zone 5b with an average last frost of April 23. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Allen County, OH?
Allen County, Ohio is in USDA Hardiness Zone 5b. The average last spring frost is April 23 and first fall frost is October 22.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Allen County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.
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