When to plant Onion in Fillmore County, MN
Onion planted in Fillmore County between April 26 and May 17 matures in 90–120 days — well before the October 6 first frost. A second sowing from July 14 to July 28 extends the harvest into fall.
When to Plant Onion in Fillmore 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.
Fillmore County, Minnesota is in USDA Zone 4b. The average last spring frost is May 3 and the first fall frost is October 6, giving you a growing season of approximately 156 days.
At an elevation of 870 feet, Fillmore County receives approximately 37.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Onion to ensure they mature before fall.
Fillmore County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Onion Planting Timeline — Fillmore County, MN
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 22 | Mar 22 – Apr 5 |
| Transplant Outdoors | May 3 | May 3 – May 17 |
| Direct Sow | April 26 | Apr 26 – May 17 |
| Harvest | August 2 | Aug 2 – Sep 20 |
| Fall Sowing | July 14 | Jul 14 – Jul 28 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Direct Sow |
| 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
156 days in Fillmore County
Growing Tips for Fillmore 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 Fillmore County, MN?
Fillmore County is in Zone 4b with an average last frost of May 3. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Fillmore County, MN?
Fillmore County, Minnesota is in USDA Hardiness Zone 4b. The average last spring frost is May 3 and first fall frost is October 6.
When should I plant Onion in Fillmore County, MN?
In Fillmore County, MN, plant Onion after the last frost (around May 3) and before the first frost (around October 6). Best results when soil holds above 50°F.
What growing zone is Fillmore County, MN for Onion?
Fillmore County sits in USDA Zone 4b. Onion grows reliably in zones 3a through 10b, so it's a good fit here.
Can Onion grow in Fillmore County's climate?
Yes — Onion grows well in Fillmore County's temperate climate. Fillmore County averages a 156-day frost-free season, with last frost around May 3 and first frost around October 6.
Your Fillmore County Garden Planner — Free
A 22-page printable planner built for Fillmore County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.