When to Plant Onion in Bay Saint Louis, Mississippi (39521)

Location

Bay Saint Louis, Mississippi

ZIP Code

39521

USDA Zone

Last Frost

Friday, February 20, 2026

📅 Planting Calendar

Start Seeds Indoors Friday, December 26, 2025

Transplant Outdoors Friday, March 6, 2026

Pro Tip: Start Onion seeds indoors 8 weeks before your last frost date, then transplant outdoors around Friday, March 6, 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 Bay Saint Louis?

Get your seeds now so they're ready by Friday, December 26, 2025.

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🤝 Good Companions

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⚠️ Avoid Planting Near

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Growing Onion in Zone 9a

Onion (Allium cepa) is a popular garden vegetable. In Bay Saint Louis, Mississippi, which is in USDA Hardiness Zone 9a, you should start seeds indoors around Friday, December 26, 2025.

Your average last frost date is Friday, February 20, 2026. Plan to transplant your Onion seedlings outdoors around Friday, March 6, 2026, about 2 weeks after your last frost date.