When to Plant Asparagus 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, February 28, 2026

Transplant Outdoors

Saturday, May 9, 2026

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

Pro tip: Start Asparagus seeds indoors 8 weeks before your last frost date, then transplant outdoors around Saturday, May 9, 2026.

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🌿 Plant Details

Scientific Name Asparagus officinalis

Days to Maturity 730 days

☀️ Growing Requirements

☀️

Sun

Full Sun

💧

Water

Regular

Seeds typically germinate in 8-21 days

Ready to Plant Asparagus in Castine?

Get your seeds now so they're ready by Saturday, February 28, 2026.

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🤝 Good Companions

TomatoAsterDillCorianderParsleyBasilComfreyMarigold

⚠️ Avoid Planting Near

OnionGarlicPotato

🤝

Full Companion Planting Guide for Asparagus

See which plants help Asparagus 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

🟡 Moderate

✅ Open-pollinated — seeds grow true to parent

When to Harvest Seed

Allow red berries to ripen fully on female plants in late summer/fall.

Processing

Mash berries to release seeds, rinse, dry flat for 2 weeks.

Seed Viability

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

Pro Tip

Asparagus is dioecious — only female plants produce berries. Male plants produce more spears, so save seed selectively.

Frequently Asked Questions

When should I plant Asparagus in Castine, Maine? +

In Castine (Zone 5b), start Asparagus seeds indoors around Saturday, February 28, 2026 and transplant outdoors around Saturday, May 9, 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 Asparagus take to grow? +

Asparagus typically matures in about 730 days from transplanting. In Castine, that means you can expect harvest around Saturday, May 9, 2026 plus 730 days.

Should I start Asparagus indoors or direct sow in Maine? +

Asparagus should be started indoors 8 weeks before your last frost date. In Castine, that means starting around Saturday, February 28, 2026.

📚 More Asparagus Planting Guides

🗺️

Asparagus in Maine

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 5b Asparagus Guide

All cities in your zone · Avg dates

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Other Plants for Castine

Blackberry Blueberry Raspberry Strawberry Basil Chamomile Chives Cilantro Dill Lavender Lemon Balm Marjoram Mint Oregano Parsley Rosemary Sage Tarragon Thyme Acorn Squash Artichoke Arugula Beefsteak Tomato Beet Bell Pepper Bok Choy Broccoli Brussels Sprout Butternut Squash Cabbage Cantaloupe Carrot Cauliflower Cayenne Pepper Celery Cherry Tomato Chili Pepper Collard Green Common Bean Cucumber Eggplant Endive Fennel Garlic Grape Tomato Green Bean Habanero Pepper Head Lettuce Heirloom Tomato Honeydew Melon Jalapeño Pepper Kale Kohlrabi Leaf Lettuce Leek Lima Bean Mustard Okra Onion Parsnip Pea Poblano Pepper Pole Pea Potato Pumpkin Radicchio Radish Rhubarb Roma Tomato Rutabaga Serrano Pepper Shallot Snap Pea Snow Pea Spaghetti Squash Spinach Squash Sweet Corn Sweet Potato Swiss Chard Tomato Turnip Watermelon Zucchini Sunflower Marigold Zinnia Nasturtium Cosmos Echinacea (Coneflower) Petunia Black-eyed Susan Apple Tree Pear Tree Peach Tree Plum Tree Sweet Cherry Tree Lemon Tree Borage Lemongrass Ginger Stevia Tomatillo Edamame Fava Bean Mâche Mizuna Sorrel Shishito Pepper Banana Pepper Watermelon Radish Napa Cabbage Popcorn Broccoli Raab Catnip Valerian Lemon Verbena Bee Balm Anise Lovage Chervil Summer Savory Dahlia Snapdragon Pansy Sweet Pea Morning Glory Hollyhock Larkspur Bachelor Button Columbine Impatiens Salvia (Annual) Sweet Alyssum Celosia Lupine Verbena Elderberry Grape Vine Red Currant Gooseberry Serviceberry Fig Tree Avocado Tree Persimmon Tree Olive Tree

Growing Asparagus in Zone 5b

Asparagus (Asparagus officinalis) is a popular garden vegetable. In Castine, Maine, which is in USDA Hardiness Zone 5b, you should start seeds indoors around Saturday, February 28, 2026.

Your average last frost date is Saturday, April 25, 2026. Plan to transplant your Asparagus seedlings outdoors around Saturday, May 9, 2026, about 2 weeks after your last frost date.