When to Plant Petunia in Fort Knox, Kentucky (40121)

Location

Fort Knox, Kentucky

ZIP Code

40121

USDA Zone

Last Frost

Friday, April 10, 2026

📅 Your 2026 Planting Dates

Start Seeds Indoors

Friday, January 30, 2026

Transplant Outdoors

Friday, April 24, 2026

Based on last frost Friday, April 10, 2026 · Zone 7a

Pro tip: Start Petunia seeds indoors 10 weeks before your last frost date, then transplant outdoors around Friday, April 24, 2026.

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🌿 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 Fort Knox?

Get your seeds now so they're ready by Friday, January 30, 2026.

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🤝 Good Companions

TomatoBasilMarigold

⚠️ Avoid Planting Near

Fennel

🤝

Full Companion Planting Guide for Petunia

See which plants help Petunia 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 to form after flowers fade. Harvest when the small pod turns tan and begins to split.

Processing

Collect tiny seeds in a bowl when pod splits, dry 1 week before storing.

Seed Viability

Up to 3 years when stored cool, dark, and dry.

Pro Tip

Most petunias are F1 hybrids — seedlings will not match the parent. Look for OP/heirloom varieties for reliable seed.

🪴

Raised Bed Planting Guides

A 4×8 bed fits 32 plants of Petunia. See plant counts, spacing grids, and companion pairings for every bed size →

Frequently Asked Questions

When should I plant Petunia in Fort Knox, Kentucky? +

In Fort Knox (Zone 7a), start Petunia seeds indoors around Friday, January 30, 2026 and transplant outdoors around Friday, April 24, 2026.

What is the last frost date for Fort Knox, Kentucky? +

The average last spring frost date for Fort Knox, Kentucky (ZIP 40121) is around Friday, April 10, 2026. This is based on NOAA climate normals for USDA Zone 7a.

How long does Petunia take to grow? +

Petunia typically matures in about 75 days from transplanting. In Fort Knox, that means you can expect harvest around Friday, April 24, 2026 plus 75 days.

Should I start Petunia indoors or direct sow in Kentucky? +

Petunia should be started indoors 10 weeks before your last frost date. In Fort Knox, that means starting around Friday, January 30, 2026.

📚 More Petunia Planting Guides

🗺️

Petunia in Kentucky

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 7a Petunia Guide

All cities in your zone · Avg dates

→

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Growing Petunia in Zone 7a

Petunia (Petunia × hybrida) is a popular garden vegetable. In Fort Knox, Kentucky, which is in USDA Hardiness Zone 7a, you should start seeds indoors around Friday, January 30, 2026.

Your average last frost date is Friday, April 10, 2026. Plan to transplant your Petunia seedlings outdoors around Friday, April 24, 2026, about 2 weeks after your last frost date.