When to Plant Watermelon Radish in Biwabik, Minnesota (55708)

Location

Biwabik, Minnesota

ZIP Code

55708

USDA Zone

Last Frost

Wednesday, May 20, 2026

📅 Your 2026 Planting Dates

Direct Sow Outdoors

Wednesday, April 22, 2026

Based on last frost Wednesday, May 20, 2026 · Zone 3b

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 Biwabik?

Get your seeds now so they're ready by Wednesday, April 22, 2026.

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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 Biwabik, Minnesota? +

In Biwabik (Zone 3b), direct sow Watermelon Radish outdoors around Wednesday, April 22, 2026.

What is the last frost date for Biwabik, Minnesota? +

The average last spring frost date for Biwabik, Minnesota (ZIP 55708) is around Wednesday, May 20, 2026. This is based on NOAA climate normals for USDA Zone 3b.

How long does Watermelon Radish take to grow? +

Watermelon Radish typically matures in about 60 days from direct sowing. In Biwabik, that means you can expect harvest around Wednesday, April 22, 2026 plus 60 days.

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

Watermelon Radish does best when direct sown outdoors. In Biwabik, sow directly around Wednesday, April 22, 2026.

📚 More Watermelon Radish Planting Guides

🗺️

Watermelon Radish in Minnesota

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 3b Watermelon Radish Guide

All cities in your zone · Avg dates

→

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Growing Watermelon Radish in Zone 3b

Watermelon Radish (Raphanus sativus) is a popular garden vegetable. In Biwabik, Minnesota, which is in USDA Hardiness Zone 3b, you should direct sow seeds around Wednesday, April 22, 2026.

Your average last frost date is Wednesday, May 20, 2026. Watermelon Radish grows well when direct sown, as it doesn't transplant well or germinates quickly outdoors.