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When to Plant Onion in Bath 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.

Bath County, Kentucky is in USDA Zone 6b. The average last spring frost is April 16 and the first fall frost is October 24, giving you a growing season of approximately 191 days.

At an elevation of 2,458 feet, Bath County receives approximately 43.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89ยฐF, providing good warmth for Onion during the growing season.

Bath County, KY (Zone 6b) Moderate season
191 days
Last Spring Frost April 16
191 growing days
First Fall Frost October 24

Bath County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (52 days to spare)
Start indoors: Mar 6 Transplant: Apr 10 🍅 Harvest: Jul 10 – Aug 28
Recommended (50%) ✓ Fits season (51 days to spare)
Start indoors: Mar 12 Transplant: Apr 16 🍅 Harvest: Jul 16 – Sep 3
Safe Start (90%) ✓ Fits season (47 days to spare)
Start indoors: Mar 28 Transplant: May 2 🍅 Harvest: Aug 1 – Sep 19

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

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 59 gal / 100 sq ft
Onion needs ~1,759 GDD — county provides 3,199 GDD Excellent fit

Onion Planting Timeline โ€” Bath County, KY

Onion Planting Calendar

Activity When Date Range
Start Indoors March 12 Mar 12 โ€“ Mar 26
Transplant Outdoors April 16 Apr 16 โ€“ Apr 30
Direct Sow April 2 Apr 2 โ€“ Apr 23
Fall Sowing August 15 Aug 15 โ€“ Aug 29
Harvest July 16 Jul 16 โ€“ Sep 3

Plant 1" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Transplant Outdoors Direct Sow
May โ€”
June โ€”
July Harvest
August Fall Sowing Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 6b

Growing Season

191 days

Growing Tips for Bath 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

  • Peas
  • Green Beans
  • Asparagus

Level Up Your Garden

Frequently Asked Questions

When should I plant Onion in Bath County, KY?

Bath County is in Zone 6b with an average last frost of April 16. Plan your Onion planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Bath County, KY?

Bath County, Kentucky is in USDA Hardiness Zone 6b. The average last spring frost is April 16 and first fall frost is October 24.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Bath County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Bath County, KY. Local conditions may vary. Last updated: April 2026.