When to Plant Petunia in Honolulu, Hawaii (96821)

Location

Honolulu, Hawaii

ZIP Code

96821

USDA Zone

12b

Last Frost

Thursday, January 1, 2026

📅 Planting Calendar

Start Seeds Indoors Thursday, October 23, 2025

Transplant Outdoors Thursday, January 15, 2026

Pro Tip: Start Petunia seeds indoors 10 weeks before your last frost date, then transplant outdoors around Thursday, January 15, 2026.

🌿 Plant Details

Scientific Name Petunia × hybrida

Days to Maturity 75 days

Mature Height 6-18"

Spread 18"

Type Annual

☀️ Growing Requirements

☀️

Sun

Full Sun (6-8 hours)

💧

Water

Moderate (1 inch/week)

↔️

Spacing

12" apart

🌱

Planting Depth

0.13" deep

Seeds typically germinate in 7-14 days

Ready to Plant Petunia in Honolulu?

Get your seeds now so they're ready by Thursday, October 23, 2025.

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🤝 Good Companions

TomatoBasilMarigold

⚠️ Avoid Planting Near

Fennel

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Growing Petunia in Zone 12b

Petunia (Petunia × hybrida) is a popular garden vegetable. In Honolulu, Hawaii, which is in USDA Hardiness Zone 12b, you should start seeds indoors around Thursday, October 23, 2025.

Your average last frost date is Thursday, January 1, 2026. Plan to transplant your Petunia seedlings outdoors around Thursday, January 15, 2026, about 2 weeks after your last frost date.