When to Plant Zinnias in Alaska
The cut-and-come-again champion. The more you cut zinnias, the more they bloom. A cottage garden essential.
The Short Answer
Alaska Frost Dates
Your planting dates depend on which part of Alaska you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Interior Alaska | 1a, 2a, 2b | May 15 - Jun 1 | Aug 20 - Sep 10 |
| Southcentral Alaska | 3b, 4a, 4b | May 1 - May 20 | Sep 10 - Sep 25 |
| Southeast Alaska | 5a, 5b, 6a | Apr 15 - May 5 | Sep 25 - Oct 15 |
Zinnias Planting Schedule for Alaska
Interior Alaska (Zones 1a, 2a, 2b)
Average last frost: May 15 - Jun 1 · Average first frost: Aug 20 - Sep 10
Southcentral Alaska (Zones 3b, 4a, 4b)
Average last frost: May 1 - May 20 · Average first frost: Sep 10 - Sep 25
Southeast Alaska (Zones 5a, 5b, 6a)
Average last frost: Apr 15 - May 5 · Average first frost: Sep 25 - Oct 15
Growing Zinnias in Alaska
Zinnias in Alaska's Climate
Zinnias are one of the best annual cut flowers for cold climates — they grow fast enough to bloom for months even in short seasons. Direct sow after your last frost when soil reaches 60°F. The more you cut, the more they bloom, producing armloads of color from July through first hard frost.
Soil Considerations for Alaska
Varies widely. Interior has permafrost challenges. Raised beds essential for warming soil. Highly acidic soils common. Make sure soil has warmed to at least 60°F before planting zinnias outside.
Alaska Climate & Growing Season
Extreme daylight variation. Summer days of 18-24 hours of sunlight accelerate growth. Very short growing season in interior. Zinnias 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 Alaska: Interior Alaska (1a, 2a, 2b) has a last frost around May 15 - Jun 1, while Southeast Alaska (5a, 5b, 6a) sees frost end around Apr 15 - May 5. This difference matters for zinnias — transplant timing shifts by several weeks across the state.
Growing Tips
Water at the base to prevent powdery mildew. Cut flowers just above a leaf node to encourage more branching and blooms.
Companion Planting
Plant zinnias alongside these companions for better growth:
The Bottom Line
Last reviewed: March 29, 2026