Blog

When to Plant Onion in Kittson County, MN

Kittson County, Minnesota Zone 3b May

May in Kittson County, Minnesota — your action list

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost May 14
Avg. first frost September 30
Soil temp (4") 50°F
Watering Low
Pest pressure Low
Daylight 15 hrs
  1. Move onion into the garden

    Frost risk is low now in Kittson County, Minnesota. If you've been covering beds overnight, you can stop.

  2. Outdoor sowing time: onion

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

Looking ahead to June
  • Starting indoors: onion

Instant PDF download. No spam, unsubscribe any time.

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.

Kittson County, Minnesota is in USDA Zone 3b. The average last spring frost is May 14 and the first fall frost is September 30, giving you a growing season of approximately 139 days.

At an elevation of 778 feet, Kittson County receives approximately 40.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 78°F, so choose short-season varieties of Onion to ensure they mature before fall.

Kittson County, MN (Zone 3b) Short season
139 days
Last Spring Frost May 14
139 growing days
First Fall Frost September 30

Kittson County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (12 days to spare)
Start indoors: Mar 28 Transplant: May 9 🍅 Harvest: Aug 8 – Sep 12
Recommended (50%) ✓ Fits season (13 days to spare)
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Aug 13 – Sep 17
Safe Start (90%) ✓ Fits season (11 days to spare)
Start indoors: Apr 18 Transplant: May 30 🍅 Harvest: Aug 29 – Oct 3

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 Kittson County

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

Soil pH

Your soil pH (6.2–7.3) overlaps with Onion's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.8%) — Onion will thrive.

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
1.2″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 1.8" 0" ❄️ Dormant
Feb 2" 0" ❄️ Dormant
Mar 3.1" 0" ❄️ Dormant
Apr 3.6" 0" ❄️ Dormant
May 4.3" 4.5" 0" ✅ Rainfall sufficient
Jun 4.3" 5.3" 0" ✅ Rainfall sufficient
Jul 4.3" 4" 0.3" 💧 Light watering
Aug 4.3" 4.2" 0.1" 💧 Light watering
Sep 4.3" 3.3" 1" 💧 Light watering
Oct 3.4" 0" ❄️ Dormant
Nov 2.9" 0" ❄️ Dormant
Dec 2.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Kittson 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 1,181 GDD Excellent fit

Onion Planting Timeline — Kittson County, MN

Onion Planting Calendar

Activity When Date Range
Start Indoors April 2 Apr 2 – Apr 16
Transplant Outdoors May 14 May 14 – May 28
Direct Sow May 7 May 7 – May 28
Harvest August 13 Aug 13 – Sep 17
Fall Sowing July 8 Jul 8 – Jul 22

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

139 days in Kittson County

Growing Tips for Onion in Kittson County

Direct sow Onion outdoors after May 14 in Kittson County when soil has warmed and frost danger has passed.

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 Kittson County, MN?

Kittson County is in Zone 3b with an average last frost of May 14. Plan your Onion planting based on this frost date — see the calendar above for exact timing.

What planting zone is Kittson County, MN?

Kittson County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is May 14 and first fall frost is September 30.

🌱

Your Kittson County Garden Planner — Free

A 24-page printable planner built for Kittson 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Kittson County, MN. 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.