When to Plant Dahlia in Hamilton, Pennsylvania (15744)

Location

Hamilton, Pennsylvania

ZIP Code

15744

USDA Zone

Last Frost

Monday, April 20, 2026

📅 Your 2026 Planting Dates

Start Seeds Indoors

Monday, March 9, 2026

Transplant Outdoors

Monday, April 27, 2026

Based on last frost Monday, April 20, 2026 · Zone 6a

Pro tip: Start Dahlia seeds indoors 6 weeks before your last frost date, then transplant outdoors around Monday, April 27, 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 Hamilton?

Get your seeds now so they're ready by Monday, March 9, 2026.

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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 Hamilton, Pennsylvania? +

In Hamilton (Zone 6a), start Dahlia seeds indoors around Monday, March 9, 2026 and transplant outdoors around Monday, April 27, 2026.

What is the last frost date for Hamilton, Pennsylvania? +

The average last spring frost date for Hamilton, Pennsylvania (ZIP 15744) is around Monday, April 20, 2026. This is based on NOAA climate normals for USDA Zone 6a.

How long does Dahlia take to grow? +

Dahlia typically matures in about 90 days from transplanting. In Hamilton, that means you can expect harvest around Monday, April 27, 2026 plus 90 days.

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

Dahlia should be started indoors 6 weeks before your last frost date. In Hamilton, that means starting around Monday, March 9, 2026.

📚 More Dahlia Planting Guides

🗺️

Dahlia in Pennsylvania

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 6a Dahlia Guide

All cities in your zone · Avg dates

→

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Growing Dahlia in Zone 6a

Dahlia (Dahlia pinnata) is a popular garden vegetable. In Hamilton, Pennsylvania, which is in USDA Hardiness Zone 6a, you should start seeds indoors around Monday, March 9, 2026.

Your average last frost date is Monday, April 20, 2026. Plan to transplant your Dahlia seedlings outdoors around Monday, April 27, 2026, about 1 weeks after your last frost date.