When to Plant Watermelon Radish in Saint Petersburg, Florida (33708)

Location

Saint Petersburg, Florida

ZIP Code

33708

USDA Zone

10b

Last Frost

Thursday, January 15, 2026

📅 Your 2026 Planting Dates

Direct Sow Outdoors

Thursday, December 18, 2025

Based on last frost Thursday, January 15, 2026 · Zone 10b

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

🌿 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 Saint Petersburg?

Get your seeds now so they're ready by Thursday, December 18, 2025.

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🤝 Good Companions

CarrotSpinachLettucePea

⚠️ Avoid Planting Near

Hyssop

See the full companion planting guide for Watermelon Radish →

🛠️ 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 Saint Petersburg, Florida? +

In Saint Petersburg (Zone 10b), direct sow Watermelon Radish outdoors around Thursday, December 18, 2025.

What is the last frost date for Saint Petersburg, Florida? +

The average last spring frost date for Saint Petersburg, Florida (ZIP 33708) is around Thursday, January 15, 2026. This is based on NOAA climate normals for USDA Zone 10b.

How long does Watermelon Radish take to grow? +

Watermelon Radish typically matures in about 60 days from direct sowing. In Saint Petersburg, that means you can expect harvest around Thursday, December 18, 2025 plus 60 days.

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

Watermelon Radish does best when direct sown outdoors. In Saint Petersburg, sow directly around Thursday, December 18, 2025.

📚 More Watermelon Radish Planting Guides

🗺️

Watermelon Radish in Florida

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 10b Watermelon Radish Guide

All cities in your zone · Avg dates

→

Other Plants for Saint Petersburg

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Growing Watermelon Radish in Zone 10b

Watermelon Radish (Raphanus sativus) is a popular garden vegetable. In Saint Petersburg, Florida, which is in USDA Hardiness Zone 10b, you should direct sow seeds around Thursday, December 18, 2025.

Your average last frost date is Thursday, January 15, 2026. Watermelon Radish grows well when direct sown, as it doesn't transplant well or germinates quickly outdoors.