When to plant Onion in Otter Tail County, MN
Spring Onion in Otter Tail County goes in May 4–May 25, once nighttime temps stop dipping near freezing. A second sowing from July 6 to July 20 extends the harvest into fall.
When to Plant Onion in Otter Tail County, MN
June in Otter Tail County, Minnesota — your action list
June is a pivotal month for Otter Tail County, Minnesota gardens. Focus on these tasks first and you'll set up the rest of the season for success.
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Indoor seed-starting week for onion
Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.
A few tasks this June that'll pay off in July
- Fall sowing: onion
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.
Otter Tail County, Minnesota is in USDA Zone 4a. The average last spring frost is May 11 and the first fall frost is September 28, giving you a growing season of approximately 140 days.
At an elevation of 571 feet, Otter Tail County receives approximately 40.3 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.
Otter Tail County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-6.8
Drainage
Well Drained
Onion Planting Risk Windows
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 Otter Tail County
How your county's soil matches Onion's growing requirements.
Soil pH
Your soil pH (6.3–6.8) is within Onion's preferred range (6.0–7.0).
Soil Texture
The silt loam soil in Otter Tail 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 (5.2%) — Onion will thrive.
How to Plant Onion
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Onion Water Budget
Water stress score is 6/10 — 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 | — | 1.9" | 0" | ❄️ Dormant |
| Feb | — | 1.8" | 0" | ❄️ Dormant |
| Mar | — | 2.4" | 0" | ❄️ Dormant |
| Apr | — | 3.4" | 0" | ❄️ Dormant |
| May | 4.3" | 4.2" | 0.1" | 💧 Light watering |
| Jun | 4.3" | 5.7" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 5" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 4.3" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Oct | — | 3.4" | 0" | ❄️ Dormant |
| Nov | — | 2.8" | 0" | ❄️ Dormant |
| Dec | — | 2.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Otter Tail 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 Planting Timeline — Otter Tail County, MN
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 30 | Mar 30 – Apr 13 |
| Transplant Outdoors | May 11 | May 11 – May 25 |
| Direct Sow | May 4 | May 4 – May 25 |
| Harvest | August 10 | Aug 10 – Sep 28 |
| Fall Sowing | July 6 | Jul 6 – Jul 20 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| 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 · Only during dry spells
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7 · Your soil: ideal
🗺️ USDA Zone
Zone 4a
📆 Growing Season
140 days in Otter Tail County
Growing Tips for Onion in Otter Tail County
Direct sow Onion outdoors after May 11 in Otter Tail 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
Check more plant combinations with our Companion Planting Checker →
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Otter Tail County, MN?
Otter Tail County is in Zone 4a with an average last frost of May 11. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Otter Tail County, MN?
Otter Tail County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 11 and first fall frost is September 28.
When should I plant Onion in Otter Tail County, MN?
In Otter Tail County, MN, plant Onion after the last frost (around May 11) and before the first frost (around September 28). Best results when soil holds above 50°F.
What growing zone is Otter Tail County, MN for Onion?
Otter Tail County sits in USDA Zone 4a. Onion grows reliably in zones 3a through 10b, so it's a good fit here.
Can Onion grow in Otter Tail County's climate?
Yes — Onion grows well in Otter Tail County's temperate climate. Otter Tail County averages a 140-day frost-free season, with last frost around May 11 and first frost around September 28.
Your Otter Tail County Garden Planner — Free
A 22-page printable planner built for Otter Tail County (Zone 4a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.