When to Plant Onion in Oneida County, ID
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.
Oneida County, Idaho is in USDA Zone 5a. The average last spring frost is May 23 and the first fall frost is September 20, giving you a growing season of approximately 120 days.
At an elevation of 8,042 feet, Oneida County receives approximately 18.4 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Onion during the growing season. With low rainfall, drip irrigation is essential for growing Onion successfully. Mulch heavily to conserve soil moisture.
Oneida County Soil Profile
Soil Type
Loam
Soil pH
6.3-8.2
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
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Onion Planting Timeline — Oneida County, ID
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 18 | Apr 18 – May 2 |
| Transplant Outdoors | May 23 | May 23 – Jun 6 |
| Direct Sow | May 9 | May 9 – May 30 |
| Fall Sowing | July 12 | Jul 12 – Jul 26 |
| Harvest | August 22 | Aug 22 – Oct 10 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Start Indoors Transplant Outdoors Direct Sow |
| June | Transplant Outdoors |
| 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 5a
Growing Season
120 days
Growing Tips for Oneida 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 Oneida County, ID?
Oneida County is in Zone 5a with an average last frost of May 23. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Oneida County, ID?
Oneida County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is May 23 and first fall frost is September 20.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Oneida County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.
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