When to Plant Arugula in Honolulu, Hawaii (96821)

Location

Honolulu, Hawaii

ZIP Code

96821

USDA Zone

12b

Last Frost

Thursday, January 1, 2026

📅 Your 2026 Planting Dates

Direct Sow Outdoors

Thursday, December 4, 2025

Based on last frost Thursday, January 1, 2026 · Zone 12b

Pro tip: Sow Arugula directly outdoors 4 weeks before your last frost date.

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🌿 Plant Details

Scientific Name Eruca vesicaria subsp. sativa

Days to Maturity 40 days

Mature Height 6-12"

Spread 6"

Type Leaf

Fruit Size N/A

☀️ Growing Requirements

☀️

Sun

Partial Shade to Full Sun

💧

Water

Regular (keep moist)

↔️

Spacing

6" apart

🌱

Planting Depth

0.25" deep

Seeds typically germinate in 3-7 days

Ready to Plant Arugula in Honolulu?

Get your seeds now so they're ready by Thursday, December 4, 2025.

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🤝 Good Companions

CarrotLettuceRadishBean

🤝

Full Companion Planting Guide for Arugula

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

🛠️ Supplies You'll Need

🪵 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

Let plants bolt and seed pods dry on the stalk. Harvest before pods shatter.

Processing

Cut stalks into a bag, dry, thresh to separate seeds from pods.

Seed Viability

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

Pro Tip

Arugula cross-pollinates readily — isolate by 300 feet from other arugula varieties for pure seed.

🪴

Raised Bed Planting Guides

A 4×8 bed fits 4 per sq ft of Arugula. See plant counts, spacing grids, and companion pairings for every bed size →

Frequently Asked Questions

When should I plant Arugula in Honolulu, Hawaii? +

In Honolulu (Zone 12b), direct sow Arugula outdoors around Thursday, December 4, 2025.

What is the last frost date for Honolulu, Hawaii? +

The average last spring frost date for Honolulu, Hawaii (ZIP 96821) is around Thursday, January 1, 2026. This is based on NOAA climate normals for USDA Zone 12b.

How long does Arugula take to grow? +

Arugula typically matures in about 40 days from direct sowing. In Honolulu, that means you can expect harvest around Thursday, December 4, 2025 plus 40 days.

Should I start Arugula indoors or direct sow in Hawaii? +

Arugula does best when direct sown outdoors. In Honolulu, sow directly around Thursday, December 4, 2025.

📚 More Arugula Planting Guides

🗺️

Arugula in Hawaii

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 12b Arugula Guide

All cities in your zone · Avg dates

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Growing Arugula in Zone 12b

Arugula (Eruca vesicaria subsp. sativa) is a popular garden vegetable. In Honolulu, Hawaii, which is in USDA Hardiness Zone 12b, you should direct sow seeds around Thursday, December 4, 2025.

Your average last frost date is Thursday, January 1, 2026. Arugula grows well when direct sown, as it doesn't transplant well or germinates quickly outdoors.