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When to Plant Sweet Potatoes in Alfalfa County, OK

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.

Alfalfa County, Oklahoma is in USDA Zone 6b. The average last spring frost is April 7 and the first fall frost is October 31, giving you a growing season of approximately 207 days.

At an elevation of 835 feet, Alfalfa County receives approximately 26.3 inches of rainfall annually with predominantly loam soil. Summer highs average 85ยฐF, providing good warmth for Sweet Potatoes during the growing season.

Alfalfa County, OK (Zone 6b) Long season
207 days
Last Spring Frost April 7
207 growing days
First Fall Frost October 31

Alfalfa County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (53 days to spare)
Start indoors: Feb 2 Transplant: Apr 13 🍅 Harvest: Jul 13 – Aug 31
Recommended (50%) ✓ Fits season (53 days to spare)
Start indoors: Feb 10 Transplant: Apr 21 🍅 Harvest: Jul 21 – Sep 8
Safe Start (90%) ✓ Fits season (57 days to spare)
Start indoors: Feb 24 Transplant: May 5 🍅 Harvest: Aug 4 – Sep 22

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
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 1,031 gal / 100 sq ft
Drought risk

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

Sweet Potatoes needs ~1,444 GDD — county provides 2,846 GDD Excellent fit

Sweet Potatoes Planting Timeline โ€” Alfalfa County, OK

Sweet Potatoes Planting Calendar

Activity When Date Range
Start Indoors February 10 Feb 10 โ€“ Feb 24
Transplant Outdoors April 21 Apr 21 โ€“ May 5
Direct Sow April 14 Apr 14 โ€“ May 5
Harvest July 21 Jul 21 โ€“ Sep 8

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

Month-by-Month Timeline

MonthActivities
January โ€”
February Start Indoors
March โ€”
April Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June โ€”
July Harvest
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 6b

Growing Season

207 days

Growing Tips for Alfalfa 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 Alfalfa County, OK?

Alfalfa County is in Zone 6b with an average last frost of April 7. Plan your Sweet Potatoes planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Alfalfa County, OK?

Alfalfa County, Oklahoma is in USDA Hardiness Zone 6b. The average last spring frost is April 7 and first fall frost is October 31.

๐ŸŒฑ

Plan Your Garden with Confidence

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

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

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