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When to Plant Sweet Potatoes in Hardin County, OH

Sweet potatoes are a warm-season root crop that produces nutritious, sweet tubers in orange, white, and purple varieties. They need a long, hot growing season.

Hardin County, Ohio is in USDA Zone 5b. The average last spring frost is April 26 and the first fall frost is October 20, giving you a growing season of approximately 177 days.

At an elevation of 935 feet, Hardin County receives approximately 30.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85ยฐF, providing good warmth for Sweet Potatoes during the growing season.

Hardin County, OH (Zone 5b) Moderate season
177 days
Last Spring Frost April 26
177 growing days
First Fall Frost October 20

Hardin County Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (27 days to spare)
Start indoors: Feb 21 Transplant: May 2 🍅 Harvest: Aug 1 – Sep 19
Recommended (50%) ✓ Fits season (23 days to spare)
Start indoors: Mar 1 Transplant: May 10 🍅 Harvest: Aug 9 – Sep 27
Safe Start (90%) ✓ Fits season (19 days to spare)
Start indoors: Mar 17 Transplant: May 26 🍅 Harvest: Aug 25 – Oct 13

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
0.7″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 439 gal / 100 sq ft
Sweet Potatoes needs ~1,444 GDD — county provides 2,433 GDD Excellent fit

Sweet Potatoes Planting Timeline โ€” Hardin County, OH

Sweet Potatoes Planting Calendar

Activity When Date Range
Start Indoors March 1 Mar 1 โ€“ Mar 15
Transplant Outdoors May 10 May 10 โ€“ May 24
Direct Sow May 3 May 3 โ€“ May 24
Harvest August 9 Aug 9 โ€“ Sep 27

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

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

5.5 โ€“ 6.5

USDA Zone

Zone 5b

Growing Season

177 days

Growing Tips for Hardin County

Plant slips (rooted sprouts) after soil is thoroughly warm. Build raised mounds for better root development. Cure harvested roots at 80-85F for 10 days to develop sweetness.

Companion Planting

Good Companions

Avoid Planting Near

  • Squash Summer

Level Up Your Garden

Frequently Asked Questions

When should I plant Sweet Potatoes in Hardin County, OH?

Hardin County is in Zone 5b with an average last frost of April 26. Plan your Sweet Potatoes planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Hardin County, OH?

Hardin County, Ohio is in USDA Hardiness Zone 5b. The average last spring frost is April 26 and first fall frost is October 20.

๐ŸŒฑ

Plan Your Garden with Confidence

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