When to Plant Dahlia in Haiku, Hawaii (96708)

Location

Haiku, Hawaii

ZIP Code

96708

USDA Zone

12a

Last Frost

Thursday, January 1, 2026

📅 Your 2026 Planting Dates

Start Seeds Indoors

Thursday, November 20, 2025

Transplant Outdoors

Thursday, January 8, 2026

Based on last frost Thursday, January 1, 2026 · Zone 12a

Pro tip: Start Dahlia seeds indoors 6 weeks before your last frost date, then transplant outdoors around Thursday, January 8, 2026.

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🌿 Plant Details

Scientific Name Dahlia pinnata

Days to Maturity 90 days

Mature Height 18-60"

Spread 18"

☀️ Growing Requirements

☀️

Sun

Full Sun (6-8 hours)

💧

Water

Regular (1-2 inches/week)

↔️

Spacing

18" apart

🌱

Planting Depth

4" deep

Seeds typically germinate in 7-14 days

Ready to Plant Dahlia in Haiku?

Get your seeds now so they're ready by Thursday, November 20, 2025.

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🤝 Good Companions

MarigoldBasilCosmos

🤝

Full Companion Planting Guide for Dahlia

See which plants help Dahlia thrive, which to keep away, and raised bed layout tips →

🛠️ Supplies You'll Need

🌱 Seed Starting Trays 🪴 Seed Starting Mix 💡 Grow Lights 🌡️ Heat Mat 🌍 Flower Garden Soil ✂️ Pruning Shears 🚿 Watering Can

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🌾 Seed Saving Guide

🟡 Moderate

⚠️ Many varieties are F1 hybrid — look for OP/heirloom types

When to Harvest Seed

Allow seed pods (behind the flower) to dry on the plant in fall.

Processing

Remove dried seed pods, extract flat seeds, dry 1 week in an open envelope.

Seed Viability

Up to 2 years when stored cool, dark, and dry.

Pro Tip

Dahlia seeds do not grow true to the parent — each seedling is a unique hybrid. Propagate named varieties by tuber division.

🪴

Raised Bed Planting Guides

A 4×8 bed fits 14 plants of Dahlia. See plant counts, spacing grids, and companion pairings for every bed size →

Frequently Asked Questions

When should I plant Dahlia in Haiku, Hawaii? +

In Haiku (Zone 12a), start Dahlia seeds indoors around Thursday, November 20, 2025 and transplant outdoors around Thursday, January 8, 2026.

What is the last frost date for Haiku, Hawaii? +

The average last spring frost date for Haiku, Hawaii (ZIP 96708) is around Thursday, January 1, 2026. This is based on NOAA climate normals for USDA Zone 12a.

How long does Dahlia take to grow? +

Dahlia typically matures in about 90 days from transplanting. In Haiku, that means you can expect harvest around Thursday, January 8, 2026 plus 90 days.

Should I start Dahlia indoors or direct sow in Hawaii? +

Dahlia should be started indoors 6 weeks before your last frost date. In Haiku, that means starting around Thursday, November 20, 2025.

📚 More Dahlia Planting Guides

🗺️

Dahlia in Hawaii

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 12a Dahlia Guide

All cities in your zone · Avg dates

→

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Growing Dahlia in Zone 12a

Dahlia (Dahlia pinnata) is a popular garden vegetable. In Haiku, Hawaii, which is in USDA Hardiness Zone 12a, you should start seeds indoors around Thursday, November 20, 2025.

Your average last frost date is Thursday, January 1, 2026. Plan to transplant your Dahlia seedlings outdoors around Thursday, January 8, 2026, about 1 weeks after your last frost date.