When to Plant Onion in Vilas 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.
Vilas County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 21 and the first fall frost is September 29, giving you a growing season of approximately 131 days.
At an elevation of 543 feet, Vilas County receives approximately 36.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Onion to ensure they mature before fall.
Vilas County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-7.3
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 — Vilas County, WI
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 9 | Apr 9 – Apr 23 |
| Transplant Outdoors | May 21 | May 21 – Jun 4 |
| Direct Sow | May 14 | May 14 – Jun 4 |
| Fall Sowing | July 7 | Jul 7 – Jul 21 |
| Harvest | August 20 | Aug 20 – Oct 8 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | Fall Sowing |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| 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
131 days
Growing Tips for Vilas 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 Vilas County, WI?
Vilas County is in Zone 4a with an average last frost of May 21. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Vilas County, WI?
Vilas County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 21 and first fall frost is September 29.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Vilas County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.
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