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When to Plant Onion in Geauga County, OH

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.

Geauga County, Ohio is in USDA Zone 5b. The average last spring frost is May 5 and the first fall frost is October 13, giving you a growing season of approximately 161 days.

At an elevation of 1,003 feet, Geauga County receives approximately 35.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Onion during the growing season.

Geauga County, OH (Zone 5b) Moderate season
161 days
Last Spring Frost May 5
161 growing days
First Fall Frost October 13

Geauga County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (22 days to spare)
Start indoors: Mar 25 Transplant: Apr 29 🍅 Harvest: Jul 29 – Sep 16
Recommended (50%) ✓ Fits season (21 days to spare)
Start indoors: Mar 31 Transplant: May 5 🍅 Harvest: Aug 4 – Sep 22
Safe Start (90%) ✓ Fits season (18 days to spare)
Start indoors: Apr 17 Transplant: May 22 🍅 Harvest: Aug 21 – Oct 9

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
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 91 gal / 100 sq ft
Onion needs ~1,522 GDD — county provides 2,334 GDD Excellent fit

Onion Planting Timeline โ€” Geauga County, OH

Onion Planting Calendar

Activity When Date Range
Start Indoors March 31 Mar 31 โ€“ Apr 14
Transplant Outdoors May 5 May 5 โ€“ May 19
Direct Sow April 21 Apr 21 โ€“ May 12
Fall Sowing August 4 Aug 4 โ€“ Aug 18
Harvest August 4 Aug 4 โ€“ Sep 22

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June โ€”
July โ€”
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 5b

Growing Season

161 days

Growing Tips for Geauga 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

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Frequently Asked Questions

When should I plant Onion in Geauga County, OH?

Geauga County is in Zone 5b with an average last frost of May 5. Plan your Onion planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Geauga County, OH?

Geauga County, Ohio is in USDA Hardiness Zone 5b. The average last spring frost is May 5 and first fall frost is October 13.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Geauga County gardeners in Zone 5b 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 Geauga County, OH. Local conditions may vary. Last updated: April 2026.