When to Plant Onion in Warren County, KY
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.
Warren County, Kentucky is in USDA Zone 6b. The average last spring frost is April 8 and the first fall frost is October 28, giving you a growing season of approximately 203 days.
At an elevation of 3,957 feet, Warren County receives approximately 44.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Onion during the growing season.
Warren County Soil Profile
Soil Type
Silt Loam
Soil pH
5.3-7
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 — Warren County, KY
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 4 | Mar 4 – Mar 18 |
| Transplant Outdoors | April 8 | Apr 8 – Apr 22 |
| Direct Sow | March 25 | Mar 25 – Apr 15 |
| Fall Sowing | August 19 | Aug 19 – Sep 2 |
| Harvest | July 8 | Jul 8 – Aug 26 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Fall Sowing |
| 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 6b
Growing Season
203 days
Growing Tips for Warren 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 Warren County, KY?
Warren County is in Zone 6b with an average last frost of April 8. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Warren County, KY?
Warren County, Kentucky is in USDA Hardiness Zone 6b. The average last spring frost is April 8 and first fall frost is October 28.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Warren County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.
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