When to Plant Sunflowers in Oregon
Few things bring more joy than a row of sunflowers turning their faces to the sun. Easy, dramatic, and pollinator-friendly.
The Short Answer
Oregon Frost Dates
Your planting dates depend on which part of Oregon you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Willamette Valley | 8a, 8b | Mar 25 - Apr 15 | Oct 15 - Nov 10 |
| Portland Metro | 8b, 9a | Mar 15 - Apr 5 | Oct 25 - Nov 15 |
| Central/Eastern Oregon | 5a, 5b, 6a, 6b | May 10 - Jun 1 | Sep 10 - Oct 1 |
| Southern Oregon Coast | 8b, 9a, 9b | Mar 5 - Mar 25 | Nov 5 - Nov 25 |
Sunflowers Planting Schedule for Oregon
Willamette Valley (Zones 8a, 8b)
Average last frost: Mar 25 - Apr 15 · Average first frost: Oct 15 - Nov 10
Portland Metro (Zones 8b, 9a)
Average last frost: Mar 15 - Apr 5 · Average first frost: Oct 25 - Nov 15
Central/Eastern Oregon (Zones 5a, 5b, 6a, 6b)
Average last frost: May 10 - Jun 1 · Average first frost: Sep 10 - Oct 1
Southern Oregon Coast (Zones 8b, 9a, 9b)
Average last frost: Mar 5 - Mar 25 · Average first frost: Nov 5 - Nov 25
Growing Sunflowers in Oregon
Sunflowers in Oregon's Climate
Sunflowers love your heat and long days. Plant earlier than northern growers — from mid-March in many warm-zone areas. The intense sun produces vibrant colors and sturdy stalks. Multiple succession plantings can provide sunflower blooms from May through November.
Soil Considerations for Oregon
Rich volcanic soils in Willamette Valley. Dry, alkaline soils east of Cascades. Acidic forest soils on coast. Generally excellent for gardening in valleys. Make sure soil has warmed to at least 55°F before planting sunflowers outside.
Oregon Climate & Growing Season
Dramatic east-west climate divide. Wet, mild winters west of Cascades. Dry, cold winters east. Year-round gardening possible in mild western valleys. 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 Oregon: Willamette Valley (8a, 8b) has a last frost around Mar 25 - Apr 15, while Southern Oregon Coast (8b, 9a, 9b) sees frost end around Mar 5 - Mar 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