When to Plant Sunflowers in Arizona
Few things bring more joy than a row of sunflowers turning their faces to the sun. Easy, dramatic, and pollinator-friendly.
The Short Answer
Arizona Frost Dates
Your planting dates depend on which part of Arizona you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Northern Arizona (Flagstaff) | 4b, 5a, 5b, 6a | May 15 - Jun 5 | Sep 15 - Oct 10 |
| Central Arizona (Phoenix) | 9a, 9b, 10a | Jan 15 - Feb 10 | Dec 1 - Dec 20 |
| Southern Arizona (Tucson) | 8b, 9a, 9b | Feb 1 - Feb 25 | Nov 20 - Dec 15 |
Sunflowers Planting Schedule for Arizona
Northern Arizona (Flagstaff) (Zones 4b, 5a, 5b, 6a)
Average last frost: May 15 - Jun 5 · Average first frost: Sep 15 - Oct 10
Central Arizona (Phoenix) (Zones 9a, 9b, 10a)
Average last frost: Jan 15 - Feb 10 · Average first frost: Dec 1 - Dec 20
Southern Arizona (Tucson) (Zones 8b, 9a, 9b)
Average last frost: Feb 1 - Feb 25 · Average first frost: Nov 20 - Dec 15
Growing Sunflowers in Arizona
Sunflowers in Arizona's Climate
Sunflowers handle extreme heat well — they're one of the few ornamental flowers that actually improve with more sun and warmth. In the desert, plant in early spring before extreme heat arrives. In subtropical Florida, sunflowers grow best during the drier, cooler months from October through March.
Soil Considerations for Arizona
Alkaline, mineral-rich desert soils. Low organic matter. Heavy amendment with compost essential. Caliche layers may need to be broken. Make sure soil has warmed to at least 55°F before planting sunflowers outside.
Arizona Climate & Growing Season
Extreme heat in summer lowlands. Two planting seasons in Phoenix — spring and fall (summer is too hot). High elevation has traditional cold-climate seasons. Sunflowers cannot tolerate any frost, so wait until all frost danger has passed before transplanting outside. Watch local forecasts carefully in spring.
Growing season length varies across Arizona: Northern Arizona (Flagstaff) (4b, 5a, 5b, 6a) has a last frost around May 15 - Jun 5, while Southern Arizona (Tucson) (8b, 9a, 9b) sees frost end around Feb 1 - Feb 25. This difference matters for sunflowers — transplant timing shifts by several weeks across the state.
Growing Tips
Direct sow is preferred — sunflowers don't love transplanting. Succession plant every 2 weeks for blooms all summer.
Companion Planting
Plant sunflowers alongside these companions for better growth:
Keep sunflowers away from:
The Bottom Line
Last reviewed: March 29, 2026