When to Plant Watermelon Radish in Haiku, Hawaii (96708)

Location

Haiku, Hawaii

ZIP Code

96708

USDA Zone

12a

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 12a

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

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🌿 Plant Details

Scientific Name Raphanus sativus

Days to Maturity 60 days

Mature Height 6-10"

Spread 4"

☀️ Growing Requirements

☀️

Sun

Full Sun (6-8 hours)

💧

Water

Regular (1-2 inches/week)

↔️

Spacing

4" apart

🌱

Planting Depth

0.5" deep

Seeds typically germinate in 3-7 days

Ready to Plant Watermelon Radish in Haiku?

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

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🤝 Good Companions

CarrotSpinachLettucePea

⚠️ Avoid Planting Near

Hyssop

🤝

Full Companion Planting Guide for Watermelon Radish

See which plants help Watermelon Radish 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

Allow plants to bolt and seed pods to fully dry and turn tan on the stalk.

Processing

Thresh dried pods, winnow to remove chaff, dry seeds 1 week before storing.

Seed Viability

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

Pro Tip

Will cross with other radish varieties — isolate by 1000 feet to maintain the distinctive interior color.

🪴

Raised Bed Planting Guides

A 4×8 bed fits 9 per sq ft of Watermelon Radish. See plant counts, spacing grids, and companion pairings for every bed size →

Frequently Asked Questions

When should I plant Watermelon Radish in Haiku, Hawaii? +

In Haiku (Zone 12a), direct sow Watermelon Radish outdoors around Thursday, December 4, 2025.

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

The average last spring frost date for Haiku, Hawaii (ZIP 96708) is around Thursday, January 1, 2026. This is based on NOAA climate normals for USDA Zone 12a.

How long does Watermelon Radish take to grow? +

Watermelon Radish typically matures in about 60 days from direct sowing. In Haiku, that means you can expect harvest around Thursday, December 4, 2025 plus 60 days.

Should I start Watermelon Radish indoors or direct sow in Hawaii? +

Watermelon Radish does best when direct sown outdoors. In Haiku, sow directly around Thursday, December 4, 2025.

📚 More Watermelon Radish Planting Guides

🗺️

Watermelon Radish in Hawaii

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 12a Watermelon Radish Guide

All cities in your zone · Avg dates

→

Other Plants for Haiku

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Growing Watermelon Radish in Zone 12a

Watermelon Radish (Raphanus sativus) is a popular garden vegetable. In Haiku, Hawaii, which is in USDA Hardiness Zone 12a, you should direct sow seeds around Thursday, December 4, 2025.

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