When to Plant Onion in California, Pennsylvania (15419)

Location

California, Pennsylvania

ZIP Code

15419

USDA Zone

Last Frost

Wednesday, April 15, 2026

📅 Planting Calendar

Start Seeds Indoors Wednesday, February 18, 2026

Transplant Outdoors Wednesday, April 29, 2026

Pro Tip: Start Onion seeds indoors 8 weeks before your last frost date, then transplant outdoors around Wednesday, April 29, 2026.

🌿 Plant Details

Scientific Name Allium cepa

Days to Maturity 100 days

Mature Height 12-18"

Spread 4"

Type Bulb

Fruit Size Medium (2-4 inch bulb)

☀️ Growing Requirements

☀️

Sun

Full Sun (6+ hours)

💧

Water

Moderate

↔️

Spacing

4" apart

🌱

Planting Depth

0.5" deep

Seeds typically germinate in 7-10 days

Ready to Plant Onion in California?

Get your seeds now so they're ready by Wednesday, February 18, 2026.

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🤝 Good Companions

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⚠️ Avoid Planting Near

BeanPeaAsparagus

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Growing Onion in Zone 6b

Onion (Allium cepa) is a popular garden vegetable. In California, Pennsylvania, which is in USDA Hardiness Zone 6b, you should start seeds indoors around Wednesday, February 18, 2026.

Your average last frost date is Wednesday, April 15, 2026. Plan to transplant your Onion seedlings outdoors around Wednesday, April 29, 2026, about 2 weeks after your last frost date.