When to Plant Onion in Graham 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.
Graham County, Arizona is in USDA Zone 7b. The average last spring frost is April 6 and the first fall frost is November 5, giving you a growing season of approximately 213 days.
At an elevation of 2,604 feet, Graham County receives approximately 8 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 98°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.
Graham County Soil Profile
Soil Type
Sandy Loam
Soil pH
7-8.8
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 10/10 — consider drought-tolerant varieties and mulching
Onion Planting Timeline — Graham County, AZ
Onion Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 2 | Mar 2 – Mar 16 |
| Transplant Outdoors | April 6 | Apr 6 – Apr 20 |
| Direct Sow | March 23 | Mar 23 – Apr 13 |
| Fall Sowing | August 27 | Aug 27 – Sep 10 |
| Harvest | July 6 | Jul 6 – Aug 24 |
Plant 1" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | — |
| 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 7b
Growing Season
213 days
Growing Tips for Graham 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 Graham County, AZ?
Graham County is in Zone 7b with an average last frost of April 6. Plan your Onion planting based on this frost date — see the calendar above for exact timing.
What planting zone is Graham County, AZ?
Graham County, Arizona is in USDA Hardiness Zone 7b. The average last spring frost is April 6 and first fall frost is November 5.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Graham County gardeners in Zone 7b organize planting dates, track what's growing, and never miss a planting window.
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