When to Plant Onion in Robertson 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.
Robertson County, Kentucky is in USDA Zone 6b. The average last spring frost is April 16 and the first fall frost is October 26, giving you a growing season of approximately 193 days.
At an elevation of 2,352 feet, Robertson County receives approximately 43 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Onion during the growing season.
Robertson County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-6.5
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
Onion Planting Timeline — Robertson County, KY
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 12 | Mar 12 – Mar 26 |
| Transplant Outdoors | April 16 | Apr 16 – Apr 30 |
| Direct Sow | April 2 | Apr 2 – Apr 23 |
| Fall Sowing | August 17 | Aug 17 – Aug 31 |
| Harvest | July 16 | Jul 16 – Sep 3 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | — |
| 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 6b
Growing Season
193 days
Growing Tips for Robertson 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 Robertson County, KY?
Robertson County is in Zone 6b with an average last frost of April 16. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Robertson County, KY?
Robertson County, Kentucky is in USDA Hardiness Zone 6b. The average last spring frost is April 16 and first fall frost is October 26.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Robertson County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.
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