When to Plant Onion in Mahoning County, OH
Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.
Mahoning County, Ohio is in USDA Zone 5b. The average last spring frost is April 30 and the first fall frost is October 18, giving you a growing season of approximately 171 days.
At an elevation of 759 feet, Mahoning County receives approximately 37.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Onion during the growing season.
Mahoning County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-6.8
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
Onion Planting Timeline — Mahoning County, OH
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 26 | Mar 26 – Apr 9 |
| Transplant Outdoors | April 30 | Apr 30 – May 14 |
| Direct Sow | April 16 | Apr 16 – May 7 |
| Fall Sowing | August 9 | Aug 9 – Aug 23 |
| Harvest | July 30 | Jul 30 – Sep 17 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Harvest |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Moderate — regular watering
Days to Maturity
90–120 days
Soil pH
6 – 7
USDA Zone
Zone 5b
Growing Season
171 days
Growing Tips for Mahoning County
Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.
Companion Planting
Good Companions
Avoid Planting Near
Level Up Your Garden
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Mahoning County, OH?
Mahoning County is in Zone 5b with an average last frost of April 30. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Mahoning County, OH?
Mahoning County, Ohio is in USDA Hardiness Zone 5b. The average last spring frost is April 30 and first fall frost is October 18.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Mahoning County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.
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