When to Plant Onion in Scott County, MN
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.
Scott County, Minnesota is in USDA Zone 4a. The average last spring frost is April 24 and the first fall frost is October 9, giving you a growing season of approximately 168 days.
At an elevation of 1,105 feet, Scott County receives approximately 39.8 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.
Scott County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-7
Drainage
Well Drained
Plant 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 Scott County
How your county's soil matches Onion's growing requirements.
Soil pH
Your soil pH (5.9–7.0) overlaps with Onion's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Scott County is excellent for Onion — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.5%) — Onion will thrive.
How to Plant Onion
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Plant Water Budget
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 | — | 1.6" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 2.5" | 0" | ❄️ Dormant |
| Apr | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| May | 4.3" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 5" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 4" | 0.3" | 💧 Light watering |
| Sep | 4.3" | 3.7" | 0.6" | 💧 Light watering |
| Oct | 4.3" | 3.1" | 1.2" | 💧 Light watering |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 2.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Scott 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 — Scott County, MN
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 13 | Mar 13 – Mar 27 |
| Transplant Outdoors | April 24 | Apr 24 – May 8 |
| Direct Sow | April 17 | Apr 17 – May 8 |
| Harvest | July 24 | Jul 24 – Sep 11 |
| Fall Sowing | July 17 | Jul 17 – Jul 31 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Fall Sowing Harvest |
| 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: acceptable
🗺️ USDA Zone
Zone 4a
📆 Growing Season
168 days in Scott County
Growing Tips for Onion in Scott County
Direct sow Onion outdoors after April 24 in Scott 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
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Check more plant combinations with our Companion Planting Checker →
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Scott County, MN?
Scott County is in Zone 4a with an average last frost of April 24. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Scott County, MN?
Scott County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is April 24 and first fall frost is October 9.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Scott County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.
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