When to Plant Cosmos in Seattle, Washington (98195)

Location

Seattle, Washington

ZIP Code

98195

USDA Zone

Last Frost

Friday, February 20, 2026

📅 Planting Calendar

Direct Sow Outdoors Friday, February 20, 2026

Pro Tip: Sow Cosmos directly outdoors around your last frost date when soil starts to warm.

🌿 Plant Details

Scientific Name Cosmos bipinnatus

Days to Maturity 60 days

Mature Height 24-60"

Spread 18"

Type Annual

☀️ Growing Requirements

☀️

Sun

Full Sun (6-8 hours)

💧

Water

Low-Moderate

↔️

Spacing

18" apart

🌱

Planting Depth

0.25" deep

Seeds typically germinate in 7-14 days

Ready to Plant Cosmos in Seattle?

Get your seeds now so they're ready by Friday, February 20, 2026.

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Growing Cosmos in Zone 9a

Cosmos (Cosmos bipinnatus) is a popular garden vegetable. In Seattle, Washington, which is in USDA Hardiness Zone 9a, you should direct sow seeds around Friday, February 20, 2026.

Your average last frost date is Friday, February 20, 2026. Cosmos grows well when direct sown, as it doesn't transplant well or germinates quickly outdoors.