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When to Plant Onion in LaMoure County, ND

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.

LaMoure County, North Dakota is in USDA Zone 4a. The average last spring frost is May 11 and the first fall frost is September 29, giving you a growing season of approximately 141 days.

At an elevation of 999 feet, LaMoure County receives approximately 21.9 inches of rainfall annually with predominantly loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Onion to ensure they mature before fall.

LaMoure County, ND (Zone 4a) Short season
141 days
Last Spring Frost May 11
141 growing days
First Fall Frost September 29

LaMoure County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (4 days to spare)
Start indoors: Mar 21 Transplant: May 2 🍅 Harvest: Aug 1 – Sep 19
Recommended (50%) ✓ Fits season (1 days to spare)
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Aug 10 – Sep 28
Safe Start (90%) ✓ Fits season (8 days to spare)
Start indoors: Apr 7 Transplant: May 19 🍅 Harvest: Aug 18 – Oct 6

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
0.4″/week
Watering frequency 1-2 times/week
Season total 524 gal / 100 sq ft
Drought risk

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

Onion needs ~1,365 GDD — county provides 1,833 GDD Excellent fit

Onion Planting Timeline โ€” LaMoure County, ND

Onion Planting Calendar

Activity When Date Range
Start Indoors March 30 Mar 30 โ€“ Apr 13
Transplant Outdoors May 11 May 11 โ€“ May 25
Direct Sow May 4 May 4 โ€“ May 25
Fall Sowing July 7 Jul 7 โ€“ Jul 21
Harvest August 10 Aug 10 โ€“ Sep 28

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
May Transplant Outdoors Direct Sow
June โ€”
July Fall Sowing
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

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

141 days

Growing Tips for LaMoure 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 LaMoure County, ND?

LaMoure County is in Zone 4a with an average last frost of May 11. Plan your Onion planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is LaMoure County, ND?

LaMoure County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 11 and first fall frost is September 29.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help LaMoure County gardeners in Zone 4a 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 LaMoure County, ND. Local conditions may vary. Last updated: April 2026.