When to Plant Onion in Cochise County, AZ
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.
Cochise County, Arizona is in USDA Zone 8a. The average last spring frost is March 30 and the first fall frost is November 9, giving you a growing season of approximately 224 days.
At an elevation of 3,447 feet, Cochise County receives approximately 9.4 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 105°F, so Onion may need afternoon shade and extra watering during peak heat. 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.
Cochise County Soil Profile
Soil Type
Sandy Loam
Soil pH
6.9-8.3
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
Water stress score is 10/10 — consider drought-tolerant varieties and mulching
Onion Planting Timeline — Cochise County, AZ
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 23 | Feb 23 – Mar 9 |
| Transplant Outdoors | March 30 | Mar 30 – Apr 13 |
| Direct Sow | March 16 | Mar 16 – Apr 6 |
| Fall Sowing | August 31 | Aug 31 – Sep 14 |
| Harvest | June 29 | Jun 29 – Aug 17 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors Transplant Outdoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | Harvest |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | Fall Sowing |
| 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 8a
Growing Season
224 days
Growing Tips for Cochise 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 Cochise County, AZ?
Cochise County is in Zone 8a with an average last frost of March 30. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Cochise County, AZ?
Cochise County, Arizona is in USDA Hardiness Zone 8a. The average last spring frost is March 30 and first fall frost is November 9.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Cochise County gardeners in Zone 8a organize planting dates, track what's growing, and never miss a planting window.
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