When to Plant Onion in Buffalo County, WI
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.
Buffalo County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 12 and the first fall frost is September 30, giving you a growing season of approximately 141 days.
At an elevation of 661 feet, Buffalo County receives approximately 36.4 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.
Buffalo County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Onion Planting Timeline — Buffalo County, WI
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 31 | Mar 31 – Apr 14 |
| Transplant Outdoors | May 12 | May 12 – May 26 |
| Direct Sow | May 5 | May 5 – May 26 |
| Harvest | August 11 | Aug 11 – Sep 29 |
| Fall Sowing | July 8 | Jul 8 – Jul 22 |
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
Moderate — regular watering
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 4b
📆 Growing Season
141 days in Buffalo County
Growing Tips for Buffalo 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
Check more plant combinations with our Companion Planting Checker →
Onion in Other Locations
Frequently Asked Questions
When should I plant Onion in Buffalo County, WI?
Buffalo County is in Zone 4b with an average last frost of May 12. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Buffalo County, WI?
Buffalo County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 12 and first fall frost is September 30.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Buffalo County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.
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