When to Plant Lemon Balm in Boulder, Colorado (80310)

Location

Boulder, Colorado

ZIP Code

80310

USDA Zone

Last Frost

Monday, April 20, 2026

📅 Planting Calendar

Start Seeds Indoors Monday, March 9, 2026

Transplant Outdoors Monday, May 4, 2026

Pro Tip: Start Lemon Balm seeds indoors 6 weeks before your last frost date, then transplant outdoors around Monday, May 4, 2026.

🌿 Plant Details

Scientific Name Melissa officinalis

Days to Maturity 70 days

Mature Height 18-36"

Spread 24"

Type Spreading

Fruit Size N/A

☀️ Growing Requirements

☀️

Sun

Partial Shade to Full Sun

💧

Water

Regular (keep moist)

↔️

Spacing

18" apart

🌱

Planting Depth

0.125" deep

Seeds typically germinate in 10-14 days

Ready to Plant Lemon Balm in Boulder?

Get your seeds now so they're ready by Monday, March 9, 2026.

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Growing Lemon Balm in Zone 6a

Lemon Balm (Melissa officinalis) is a popular garden vegetable. In Boulder, Colorado, which is in USDA Hardiness Zone 6a, you should start seeds indoors around Monday, March 9, 2026.

Your average last frost date is Monday, April 20, 2026. Plan to transplant your Lemon Balm seedlings outdoors around Monday, May 4, 2026, about 2 weeks after your last frost date.