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When to Plant Onion in Roger Mills County, OK

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.

Roger Mills County, Oklahoma is in USDA Zone 7a. The average last spring frost is April 13 and the first fall frost is October 23, giving you a growing season of approximately 193 days.

At an elevation of 697 feet, Roger Mills County receives approximately 27.7 inches of rainfall annually with predominantly loam soil. Summer highs average 92ยฐF, providing good warmth for Onion during the growing season.

Roger Mills County, OK (Zone 7a) Moderate season
193 days
Last Spring Frost April 13
193 growing days
First Fall Frost October 23

Roger Mills County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (55 days to spare)
Start indoors: Feb 28 Transplant: Apr 4 🍅 Harvest: Jul 4 – Aug 22
Recommended (50%) ✓ Fits season (53 days to spare)
Start indoors: Mar 9 Transplant: Apr 13 🍅 Harvest: Jul 13 – Aug 31
Safe Start (90%) ✓ Fits season (56 days to spare)
Start indoors: Mar 24 Transplant: Apr 28 🍅 Harvest: Jul 28 – Sep 15

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
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 819 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Onion needs ~1,995 GDD — county provides 3,667 GDD Excellent fit

Onion Planting Timeline โ€” Roger Mills County, OK

Onion Planting Calendar

Activity When Date Range
Start Indoors March 9 Mar 9 โ€“ Mar 23
Transplant Outdoors April 13 Apr 13 โ€“ Apr 27
Direct Sow March 30 Mar 30 โ€“ Apr 20
Fall Sowing August 14 Aug 14 โ€“ Aug 28
Harvest July 13 Jul 13 โ€“ Aug 31

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 โ€”
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 7a

Growing Season

193 days

Growing Tips for Roger Mills 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 Roger Mills County, OK?

Roger Mills County is in Zone 7a with an average last frost of April 13. Plan your Onion planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Roger Mills County, OK?

Roger Mills County, Oklahoma is in USDA Hardiness Zone 7a. The average last spring frost is April 13 and first fall frost is October 23.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Roger Mills County gardeners in Zone 7a 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 Roger Mills County, OK. Local conditions may vary. Last updated: April 2026.