When to Plant Onion in Millard County, UT
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.
Millard County, Utah is in USDA Zone 5b. The average last spring frost is May 16 and the first fall frost is September 30, giving you a growing season of approximately 137 days.
At an elevation of 6,525 feet, Millard County receives approximately 24 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Onion to ensure they mature before fall.
Millard County Soil Profile
Soil Type
Loam
Soil pH
6.5-8
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 — Millard County, UT
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 11 | Apr 11 – Apr 25 |
| Transplant Outdoors | May 16 | May 16 – May 30 |
| Direct Sow | May 2 | May 2 – May 23 |
| Fall Sowing | July 22 | Jul 22 – Aug 5 |
| Harvest | August 15 | Aug 15 – Oct 3 |
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 | — |
| July | Fall Sowing |
| August | Fall Sowing 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 5b
Growing Season
137 days
Growing Tips for Millard 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 Millard County, UT?
Millard County is in Zone 5b with an average last frost of May 16. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Millard County, UT?
Millard County, Utah is in USDA Hardiness Zone 5b. The average last spring frost is May 16 and first fall frost is September 30.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Millard County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.
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