When to Plant Onion in Hennepin 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.
Hennepin County, Minnesota is in USDA Zone 4a. The average last spring frost is April 23 and the first fall frost is October 9, giving you a growing season of approximately 169 days.
At an elevation of 694 feet, Hennepin County receives approximately 36.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Onion to ensure they mature before fall.
Hennepin County Soil Profile
Soil Type
Silt Loam
Soil pH
6.1-7.2
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.
Plant Water Budget
Onion Planting Timeline — Hennepin County, MN
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 12 | Mar 12 – Mar 26 |
| Transplant Outdoors | April 23 | Apr 23 – May 7 |
| Direct Sow | April 16 | Apr 16 – May 7 |
| Fall Sowing | July 17 | Jul 17 – Jul 31 |
| Harvest | July 23 | Jul 23 – Sep 10 |
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
Moderate — regular watering
Days to Maturity
90–120 days
Soil pH
6 – 7
USDA Zone
Zone 4a
Growing Season
169 days
Growing Tips for Hennepin County
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
Level Up Your Garden
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Hennepin County, MN?
Hennepin County is in Zone 4a with an average last frost of April 23. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Hennepin County, MN?
Hennepin County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is April 23 and first fall frost is October 9.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Hennepin County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.
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