When to Plant Radish in Cedar Glen, California (92321)

Location

Cedar Glen, California

ZIP Code

92321

USDA Zone

Last Frost

Friday, March 20, 2026

📅 Your 2026 Planting Dates

Direct Sow Outdoors

Friday, February 6, 2026

Based on last frost Friday, March 20, 2026 · Zone 8a

Pro tip: Sow Radish directly outdoors 6 weeks before your last frost date.

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🌿 Plant Details

Scientific Name Rhaphanus sativus

Days to Maturity 25 days

Mature Height 6-12"

Spread 3"

Type Root

Fruit Size Small (1-2 inches)

☀️ Growing Requirements

☀️

Sun

Full Sun to Partial Shade

💧

Water

Regular (keep moist)

↔️

Spacing

2" apart

🌱

Planting Depth

0.5" deep

Seeds typically germinate in 3-7 days

Ready to Plant Radish in Cedar Glen?

Get your seeds now so they're ready by Friday, February 6, 2026.

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🤝 Good Companions

CarrotLettucePeaCucumberSpinach

⚠️ Avoid Planting Near

Hyssop

🤝

Full Companion Planting Guide for Radish

See which plants help 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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Common Radish Varieties

Popular cultivars to look for at your local nursery or seed supplier.

Cherry Belle

spring 22d

Round, bright red radish that matures in just 22 days; the classic spring radish.

French Breakfast

spring 25d

Elongated red-tipped radish with milder flavor and crisp, white interior.

Watermelon (Shinrimei)

daikon 60d

Chinese daikon with green exterior and stunning magenta-pink interior; mild and sweet.

Daikon

daikon 60d

Long, white Japanese radish used fresh, pickled, or cooked; much larger and milder than spring types.

Common Radish Problems

What to watch for — and how to fix it before it spreads.

🐛

Pests

Flea Beetle

Tiny beetles make hundreds of small holes in leaves; seedlings can be badly damaged.

Fix:

Use row covers immediately after sowing; apply diatomaceous earth; sow densely and sacrifice outer rows.

Cabbage Root Maggot

Fly larvae tunnel into roots, leaving rusty tunnels and stunting plants.

Fix:

Use row covers from sowing; delay planting spring radishes until after peak fly emergence.

🍂

Diseases

Downy Mildew

Yellow patches on leaves with gray spores beneath; common in cool, wet springs.

Fix:

Improve airflow; avoid overhead watering; rotate with non-brassica crops.

Black Root

Interior of roots turns gray-black from Aphanomyces fungus; common in wet, acidic soils.

Fix:

Raise soil pH to 6.5–7.0; rotate crops; use certified disease-free seed.

💡

Common Mistakes

Sowing too late in the season

Radishes bolt immediately in heat, going straight to flowers without forming a root.

Fix:

Sow in early spring and again in late summer/fall; avoid sowing when temps will exceed 75°F.

Leaving in the ground too long

Radishes go pithy and hollow quickly after reaching mature size.

Fix:

Check spring radishes starting at day 20–25; harvest when roots reach pencil-width to marble-size.

🌾 Seed Saving Guide

🟢 Easy

✅ Open-pollinated — seeds grow true to parent

When to Harvest Seed

Let plants bolt and seed pods dry completely on the plant until papery and tan.

Processing

Thresh dried pods to release round seeds, winnow to remove chaff.

Seed Viability

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

Pro Tip

Radishes cross readily between varieties and with wild radish — isolate by 1000 feet for pure seed.

🪴

Raised Bed Planting Guides

A 4×8 bed fits 36 per sq ft of Radish. See plant counts, spacing grids, and companion pairings for every bed size →

Frequently Asked Questions

When should I plant Radish in Cedar Glen, California? +

In Cedar Glen (Zone 8a), direct sow Radish outdoors around Friday, February 6, 2026.

What is the last frost date for Cedar Glen, California? +

The average last spring frost date for Cedar Glen, California (ZIP 92321) is around Friday, March 20, 2026. This is based on NOAA climate normals for USDA Zone 8a.

How long does Radish take to grow? +

Radish typically matures in about 25 days from direct sowing. In Cedar Glen, that means you can expect harvest around Friday, February 6, 2026 plus 25 days.

Should I start Radish indoors or direct sow in California? +

Radish does best when direct sown outdoors. In Cedar Glen, sow directly around Friday, February 6, 2026.

📚 More Radish Planting Guides

🗺️

Radish in California

Zone-by-zone breakdown · Full state guide

→ 🌡️

Zone 8a Radish Guide

All cities in your zone · Avg dates

→

Other Plants for Cedar Glen

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Growing Radish in Zone 8a

Radish (Rhaphanus sativus) is a popular garden vegetable. In Cedar Glen, California, which is in USDA Hardiness Zone 8a, you should direct sow seeds around Friday, February 6, 2026.

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