🌱 MyLocalPlanting

When to Plant Onion in Isabella, Minnesota (55607)

Location

Isabella, Minnesota

ZIP Code

55607

USDA Zone

3b

Last Frost

Wednesday, May 20, 2026

📅 Planting Calendar

Start Seeds Indoors Wednesday, March 25, 2026
Transplant Outdoors Wednesday, June 3, 2026

Pro Tip: Start Onion seeds indoors 8 weeks before your last frost date for best results.

🌿 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

🤝 Good Companions

CarrotBeetLettuceTomatoBrassicas

⚠️ Avoid Planting Near

BeanPeaAsparagus

Other Plants for Isabella

Growing Onion in Zone 3b

Onion (Allium cepa) is a popular garden vegetable. In Isabella, Minnesota, which is in USDA Hardiness Zone 3b, you should start seeds indoors around Wednesday, March 25, 2026.

Your average last frost date is Wednesday, May 20, 2026. Plan to transplant your Onion seedlings outdoors around Wednesday, June 3, 2026, about 2 weeks after your last frost date.