When to Plant Collard Green in Castine, Maine (04421)

Location

Castine, Maine

ZIP Code

04421

USDA Zone

Last Frost

Saturday, April 25, 2026

📅 Your 2026 Planting Dates

Start Seeds Indoors

Saturday, March 14, 2026

Transplant Outdoors

Saturday, April 25, 2026

Based on last frost Saturday, April 25, 2026 · Zone 5b

Pro tip: Start Collard Green seeds indoors 6 weeks before your last frost date, then transplant outdoors around Saturday, April 25, 2026.

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🌿 Plant Details

Scientific Name Brassica oleracea var. viridis

Days to Maturity 60 days

Mature Height 24-36"

Spread 18"

Type Leaf

Fruit Size N/A

☀️ Growing Requirements

☀️

Sun

Full Sun (6+ hours)

💧

Water

Regular (1-1.5 inches/week)

↔️

Spacing

18" apart

🌱

Planting Depth

0.5" deep

Seeds typically germinate in 4-7 days

Ready to Plant Collard Green in Castine?

Get your seeds now so they're ready by Saturday, March 14, 2026.

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🤝 Good Companions

BeetCeleryOnionDill

⚠️ Avoid Planting Near

TomatoStrawberryPepper

🤝

Full Companion Planting Guide for Collard Green

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

🛠️ Supplies You'll Need

🌱 Seed Starting Trays 🪴 Seed Starting Mix 💡 Grow Lights 🌡️ Heat Mat 🪵 Raised Garden Bed 🌍 Vegetable Garden Soil 🛠️ Hand Trowel Set 🚿 Watering Can

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🌾 Seed Saving Guide

🔴 Difficult

✅ Open-pollinated — seeds grow true to parent

When to Harvest Seed

Harvest seed pods when dry and tan, before they shatter.

Processing

Thresh dried seed stalks, winnow to separate seeds from chaff.

Seed Viability

Up to 5 years when stored cool, dark, and dry.

Pro Tip

B. oleracea — crosses with all other oleracea crops including kale, broccoli, and cabbage.

🪴

Raised Bed Planting Guides

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

Frequently Asked Questions

When should I plant Collard Green in Castine, Maine? +

In Castine (Zone 5b), start Collard Green seeds indoors around Saturday, March 14, 2026 and transplant outdoors around Saturday, April 25, 2026.

What is the last frost date for Castine, Maine? +

The average last spring frost date for Castine, Maine (ZIP 04421) is around Saturday, April 25, 2026. This is based on NOAA climate normals for USDA Zone 5b.

How long does Collard Green take to grow? +

Collard Green typically matures in about 60 days from transplanting. In Castine, that means you can expect harvest around Saturday, April 25, 2026 plus 60 days.

Should I start Collard Green indoors or direct sow in Maine? +

Collard Green should be started indoors 6 weeks before your last frost date. In Castine, that means starting around Saturday, March 14, 2026.

📚 More Collard Green Planting Guides

🗺️

Collard Green in Maine

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 5b Collard Green Guide

All cities in your zone · Avg dates

→

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Growing Collard Green in Zone 5b

Collard Green (Brassica oleracea var. viridis) is a popular garden vegetable. In Castine, Maine, which is in USDA Hardiness Zone 5b, you should start seeds indoors around Saturday, March 14, 2026.

Your average last frost date is Saturday, April 25, 2026. Plan to transplant your Collard Green seedlings outdoors around Saturday, April 25, 2026, about 0 weeks after your last frost date.