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When to Plant Potatoes in Mahnomen County, MN

Potatoes are a versatile staple crop that produces tubers underground. They come in hundreds of varieties with varying colors, textures, and maturity dates.

Mahnomen County, Minnesota is in USDA Zone 3b. The average last spring frost is May 13 and the first fall frost is September 27, giving you a growing season of approximately 137 days.

At an elevation of 1,223 feet, Mahnomen County receives approximately 33.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Potatoes to ensure they mature before fall.

Mahnomen County, MN (Zone 3b) Short season
137 days
Last Spring Frost May 13
137 growing days
First Fall Frost September 27

Mahnomen County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 5 Transplant: May 28 🍅 Harvest: Aug 6 – Oct 1
Recommended (50%) ✗ May not fit
Start indoors: Mar 11 Transplant: Jun 3 🍅 Harvest: Aug 12 – Oct 7
Safe Start (90%) ✗ May not fit
Start indoors: Mar 21 Transplant: Jun 13 🍅 Harvest: Aug 22 – Oct 17

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
1.0″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 348 gal / 100 sq ft
Potatoes needs ~950 GDD — county provides 1,370 GDD Excellent fit

Potatoes Planting Timeline โ€” Mahnomen County, MN

Potatoes Planting Calendar

Activity When Date Range
Start Indoors March 11 Mar 11 โ€“ Mar 25
Transplant Outdoors June 3 Jun 3 โ€“ Jun 17
Direct Sow May 27 May 27 โ€“ Jun 17
Harvest August 12 Aug 12 โ€“ Oct 7

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 Direct Sow
June Transplant Outdoors Direct Sow
July โ€”
August Harvest
September Harvest
October Harvest
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

70โ€“120 days

Soil pH

5 โ€“ 6.5

USDA Zone

Zone 3b

Growing Season

137 days

Growing Tips for Mahnomen County

Plant seed potatoes (not grocery store potatoes) 4 inches deep in spring. Hill soil around stems as plants grow to prevent greening. Stop watering when plants die back.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Cucumber
  • Squash Summer

Level Up Your Garden

Frequently Asked Questions

When should I plant Potatoes in Mahnomen County, MN?

Mahnomen County is in Zone 3b with an average last frost of May 13. Plan your Potatoes planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Mahnomen County, MN?

Mahnomen County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is May 13 and first fall frost is September 27.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Mahnomen County gardeners in Zone 3b 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 Mahnomen County, MN. Local conditions may vary. Last updated: April 2026.