When to Plant Onion in Sandoval County, NM
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.
Sandoval County, New Mexico is in USDA Zone 6b. The average last spring frost is May 10 and the first fall frost is October 5, giving you a growing season of approximately 148 days.
At an elevation of 4,259 feet, Sandoval County receives approximately 13.2 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 91°F, providing good warmth for Onion during the growing season. Sandy soil warms quickly in spring — great for early planting — but Onion will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Onion successfully. Mulch heavily to conserve soil moisture.
Sandoval County Soil Profile
Soil Type
Sandy Loam
Soil pH
7.1-8.6
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 10/10 — consider drought-tolerant varieties and mulching
Onion Planting Timeline — Sandoval County, NM
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 5 | Apr 5 – Apr 19 |
| Transplant Outdoors | May 10 | May 10 – May 24 |
| Direct Sow | April 26 | Apr 26 – May 17 |
| Fall Sowing | July 27 | Jul 27 – Aug 10 |
| Harvest | August 9 | Aug 9 – Sep 27 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Fall Sowing |
| August | Fall Sowing 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
6 – 7
USDA Zone
Zone 6b
Growing Season
148 days
Growing Tips for Sandoval 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 Sandoval County, NM?
Sandoval County is in Zone 6b with an average last frost of May 10. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Sandoval County, NM?
Sandoval County, New Mexico is in USDA Hardiness Zone 6b. The average last spring frost is May 10 and first fall frost is October 5.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Sandoval County gardeners in Zone 6b organize planting dates, track what's growing, and never miss a planting window.
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