When to Plant Fennel in Bothell, Washington (98021)

Location

Bothell, Washington

ZIP Code

98021

USDA Zone

Last Frost

Sunday, March 15, 2026

📅 Your 2026 Planting Dates

Start Seeds Indoors

Sunday, February 15, 2026

Transplant Outdoors

Sunday, March 1, 2026

Based on last frost Sunday, March 15, 2026 · Zone 8b

Pro tip: Start Fennel seeds indoors 4 weeks before your last frost date, then transplant outdoors around Sunday, March 1, 2026.

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🌿 Plant Details

Scientific Name Foeniculum vulgare

Days to Maturity 80 days

☀️ Growing Requirements

☀️

Sun

Full Sun

💧

Water

Regular

Seeds typically germinate in 7-14 days

Ready to Plant Fennel in Bothell?

Get your seeds now so they're ready by Sunday, February 15, 2026.

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🤝 Good Companions

Dill

🤝

Full Companion Planting Guide for Fennel

See which plants help Fennel 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

🟢 Easy

✅ Open-pollinated — seeds grow true to parent

When to Harvest Seed

Harvest umbels when seeds turn gray-green to brown — just before they drop.

Processing

Cut seed heads into a bag, dry 1–2 weeks, thresh to separate seeds.

Seed Viability

Up to 4 years when stored cool, dark, and dry.

Pro Tip

Fennel cross-pollinates with dill — keep at least 300 feet apart or sacrifice one crop when saving seed.

Frequently Asked Questions

When should I plant Fennel in Bothell, Washington? +

In Bothell (Zone 8b), start Fennel seeds indoors around Sunday, February 15, 2026 and transplant outdoors around Sunday, March 1, 2026.

What is the last frost date for Bothell, Washington? +

The average last spring frost date for Bothell, Washington (ZIP 98021) is around Sunday, March 15, 2026. This is based on NOAA climate normals for USDA Zone 8b.

How long does Fennel take to grow? +

Fennel typically matures in about 80 days from transplanting. In Bothell, that means you can expect harvest around Sunday, March 1, 2026 plus 80 days.

Should I start Fennel indoors or direct sow in Washington? +

Fennel should be started indoors 4 weeks before your last frost date. In Bothell, that means starting around Sunday, February 15, 2026.

📚 More Fennel Planting Guides

🗺️

Fennel in Washington

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 8b Fennel Guide

All cities in your zone · Avg dates

→

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Growing Fennel in Zone 8b

Fennel (Foeniculum vulgare) is a popular garden vegetable. In Bothell, Washington, which is in USDA Hardiness Zone 8b, you should start seeds indoors around Sunday, February 15, 2026.

Your average last frost date is Sunday, March 15, 2026. Plan to transplant your Fennel seedlings outdoors around Sunday, March 1, 2026, about -2 weeks after your last frost date.