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When to Plant Onion in Bottineau County, ND

Bottineau County, North Dakota Zone 3b May

May in the garden — Bottineau County, North Dakota

Your garden in Bottineau County, North Dakota is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost May 15
Avg. first frost September 23
Soil temp (4") 48°F
Watering Moderate
Pest pressure Low
Daylight 15 hrs
  1. Move onion from tray to bed

    Frost risk is low now in Bottineau County, North Dakota. If you've been covering beds overnight, you can stop.

  2. Put onion seeds straight in the ground

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

Coming up in June — start thinking about
  • Starting indoors: onion

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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.

Bottineau County, North Dakota is in USDA Zone 3b. The average last spring frost is May 15 and the first fall frost is September 23, giving you a growing season of approximately 131 days.

At an elevation of 822 feet, Bottineau County receives approximately 33.3 inches of rainfall annually with predominantly loam soil. Summer highs average 78°F, so choose short-season varieties of Onion to ensure they mature before fall.

Bottineau County, ND (Zone 3b) Short season
131 days
Last Spring Frost May 15
131 growing days
First Fall Frost September 23

Bottineau County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (5 days to spare)
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Aug 10 – Sep 14
Recommended (50%) ✓ Fits season (5 days to spare)
Start indoors: Apr 3 Transplant: May 15 🍅 Harvest: Aug 14 – Sep 18
Safe Start (90%) ✓ Fits season (6 days to spare)
Start indoors: Apr 16 Transplant: May 28 🍅 Harvest: Aug 27 – Oct 1

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.

Soil Compatibility in Bottineau County

How your county's soil matches Onion's growing requirements.

Soil pH

Your soil pH (6.4–7.3) overlaps with Onion's range (6.0–7.0), though not a perfect match.

Soil Texture

The loam soil in Bottineau County is excellent for Onion — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Onion.

How to Plant Onion

1"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Onion

Onion needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Onion Needs Rainfall You Supplement Action
Jan 2.3" 0" ❄️ Dormant
Feb 1.9" 0" ❄️ Dormant
Mar 3" 0" ❄️ Dormant
Apr 3.9" 0" ❄️ Dormant
May 4.3" 3.5" 0.8" 💧 Light watering
Jun 4.3" 2.7" 1.6" 💧 Light watering
Jul 4.3" 3.1" 1.2" 💧 Light watering
Aug 4.3" 3.4" 0.9" 💧 Light watering
Sep 4.3" 2.7" 1.6" 💧 Light watering
Oct 2.6" 0" ❄️ Dormant
Nov 2.4" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Bottineau County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Onion Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Onion needs ~892 GDD — county provides 1,113 GDD Good fit

Onion Planting Timeline — Bottineau County, ND

Onion Planting Calendar

Activity When Date Range
Start Indoors April 3 Apr 3 – Apr 17
Transplant Outdoors May 15 May 15 – May 29
Direct Sow May 8 May 8 – May 29
Harvest August 14 Aug 14 – Sep 18
Fall Sowing July 1 Jul 1 – Jul 15

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June
July Fall Sowing
August Harvest
September Harvest
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 3b

📆 Growing Season

131 days in Bottineau County

Growing Tips for Onion in Bottineau County

Direct sow Onion outdoors after May 15 in Bottineau County when soil has warmed and frost danger has passed.

Your 131.0-day growing season in Bottineau County is tight for Onion (90.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Onion in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Onion in Bottineau County, ND?

Bottineau County is in Zone 3b with an average last frost of May 15. Plan your Onion planting based on this frost date — see the calendar above for exact timing.

What planting zone is Bottineau County, ND?

Bottineau County, North Dakota is in USDA Hardiness Zone 3b. The average last spring frost is May 15 and first fall frost is September 23.

🌱

Your Bottineau County Garden Planner — Free

A 24-page printable planner built for Bottineau County (Zone 3b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Bottineau County, ND. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.