Blog

When to Plant Onion in Lake of the Woods County, MN

Lake of the Woods County, Minnesota Zone 3b May

May in the garden — Lake of the Woods County, Minnesota

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Lake of the Woods County, Minnesota.

Avg. last frost May 19
Avg. first frost September 22
Soil temp (4") 52°F
Watering Low
Pest pressure Low
Daylight 15 hrs
  1. Get onion in the ground

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

  2. Put onion seeds straight in the ground

    Your soil is 52°F — warm enough for these to germinate without babying.

Looking ahead to June
  • Starting indoors: onion
  • Fall sowing: 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.

Lake of the Woods County, Minnesota is in USDA Zone 3b. The average last spring frost is May 19 and the first fall frost is September 22, giving you a growing season of approximately 126 days.

At an elevation of 1,032 feet, Lake of the Woods County receives approximately 32.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Onion to ensure they mature before fall.

Lake of the Woods County, MN (Zone 3b) Short season
126 days
Last Spring Frost May 19
126 growing days
First Fall Frost September 22
Share this guide:

Lake of the Woods County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Aug 13 – Sep 17
Recommended (50%) ✓ Fits season (0 days to spare)
Start indoors: Apr 7 Transplant: May 19 🍅 Harvest: Aug 18 – Sep 22
Safe Start (90%) ✓ Fits season (0 days to spare)
Start indoors: Apr 22 Transplant: Jun 3 🍅 Harvest: Sep 2 – Oct 7

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 Lake of the Woods County

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

Soil pH

Your soil pH (5.7–7.2) overlaps with Onion's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Onion.

Organic Matter

Organic matter is excellent (5.0%) — 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
1.1″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 228 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 1.2" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 2.8" 0" ❄️ Dormant
May 4.3" 4.4" 0" ✅ Rainfall sufficient
Jun 4.3" 4" 0.3" 💧 Light watering
Jul 4.3" 3.6" 0.7" 💧 Light watering
Aug 4.3" 3.3" 1" 💧 Light watering
Sep 4.3" 3" 1.3" 💧 Light watering
Oct 2.2" 0" ❄️ Dormant
Nov 2.6" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Lake of the Woods 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 ~1,050 GDD — county provides 1,260 GDD Good fit

Onion Planting Timeline — Lake of the Woods County, MN

Onion Planting Calendar

Activity When Date Range
Start Indoors April 7 Apr 7 – Apr 21
Transplant Outdoors May 19 May 19 – Jun 2
Direct Sow May 12 May 12 – Jun 2
Harvest August 18 Aug 18 – Sep 22
Fall Sowing June 30 Jun 30 – Jul 14

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 Transplant Outdoors Direct Sow Fall Sowing
July Fall Sowing
August Harvest
September Harvest
October
November
December
Share this guide:

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 3b

📆 Growing Season

126 days in Lake of the Woods County

Growing Tips for Onion in Lake of the Woods County

Direct sow Onion outdoors after May 19 in Lake of the Woods County when soil has warmed and frost danger has passed.

Your 126.0-day growing season in Lake of the Woods 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 Lake of the Woods County, MN?

Lake of the Woods County is in Zone 3b with an average last frost of May 19. Plan your Onion planting based on this frost date — see the calendar above for exact timing.

What planting zone is Lake of the Woods County, MN?

Lake of the Woods County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is May 19 and first fall frost is September 22.

🌱

Your Lake of the Woods County Garden Planner — Free

A 24-page printable planner built for Lake of the Woods 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 Lake of the Woods 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.