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When to Plant Onion in Madison County, AR

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.

Madison County, Arkansas is in USDA Zone 6b. The average last spring frost is April 6 and the first fall frost is October 29, giving you a growing season of approximately 206 days.

At an elevation of 801 feet, Madison County receives approximately 54.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90ยฐF, providing good warmth for Onion during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Onion root diseases.

Madison County, AR (Zone 6b) Long season
206 days
Last Spring Frost April 6
206 growing days
First Fall Frost October 29

Madison County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (72 days to spare)
Start indoors: Feb 19 Transplant: Mar 26 🍅 Harvest: Jun 25 – Aug 13
Recommended (50%) ✓ Fits season (66 days to spare)
Start indoors: Mar 2 Transplant: Apr 6 🍅 Harvest: Jul 6 – Aug 24
Safe Start (90%) ✓ Fits season (66 days to spare)
Start indoors: Mar 17 Transplant: Apr 21 🍅 Harvest: Jul 21 – Sep 8

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
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Onion needs ~1,838 GDD — county provides 3,605 GDD Excellent fit

Onion Planting Timeline โ€” Madison County, AR

Onion Planting Calendar

Activity When Date Range
Start Indoors March 2 Mar 2 โ€“ Mar 16
Transplant Outdoors April 6 Apr 6 โ€“ Apr 20
Direct Sow March 23 Mar 23 โ€“ Apr 13
Fall Sowing August 20 Aug 20 โ€“ Sep 3
Harvest July 6 Jul 6 โ€“ Aug 24

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

Month-by-Month Timeline

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

206 days

Growing Tips for Madison 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 Madison County, AR?

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

What planting zone is Madison County, AR?

Madison County, Arkansas is in USDA Hardiness Zone 6b. The average last spring frost is April 6 and first fall frost is October 29.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Madison 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 Madison County, AR. Local conditions may vary. Last updated: April 2026.