How to Grow Spearmint Seeds

Spearmint (Mentha spicata) is a fast-growing, aromatic herb known for its refreshing flavor and versatility in teas, cooking, and home remedies. While many gardeners propagate mint from cuttings, growing spearmint from seed is simple and rewarding when done correctly.

What Is Spearmint?

Spearmint (Mentha spicata) is a hardy perennial herb in the mint family. It produces bright green, serrated leaves with a sweet, mild mint flavor.

• Plant Type: Perennial herb
• Flavor Profile: Sweet, mild mint
• Mature Height: 12–36 inches
• Sun Requirements: Full sun to partial shade

When to Plant Spearmint Seeds

• Indoors: Start seeds 6–8 weeks before your last frost
• Outdoors: Sow after all danger of frost has passed
• Ideal Soil Temperature: 65–75°F

For colder climates like Vermont, starting seeds indoors in early spring gives the best results.

How to Plant Spearmint Seeds

Spearmint seeds are very small and require light to germinate, so proper planting technique is important.

Step-by-Step Instructions:

1. Prepare the Soil
   Use a light, well-draining seed-starting mix.
2. Sow the Seeds
   Sprinkle seeds evenly on the surface of the soil. Do not cover them.
3. Press Gently
   Lightly press seeds into the soil to ensure good contact.
4. Water Carefully
   Mist the surface to keep it moist without washing seeds away.
5. Provide Light
   Place in a bright window or under grow lights.
6. Maintain Temperature
   Keep soil consistently between 65–75°F.

Germination Time

• Sprouting Time: 10–16 days
• Keep soil evenly moist during this period
• Optional: Use a humidity dome or plastic cover to retain moisture

Transplanting Seedlings

Once seedlings develop 2–3 true leaves, they are ready for transplanting.

• Space plants 12–18 inches apart
• Harden off seedlings before moving outdoors
• Consider planting in containers to control spreading

Growing Conditions for Spearmint

Spearmint thrives with minimal care when given the right environment:

• Sunlight: Full sun to partial shade
• Soil: Rich, moist, well-draining soil
• Watering: Keep soil consistently moist, not soggy
• Fertilizer: Light feeding once per month

Controlling Spread (Important)

Spearmint spreads aggressively through underground runners.

• Grow in containers to prevent takeover
• Use barriers or edging if planting in the ground
• Regular pruning helps control growth

Harvesting Spearmint

• Begin harvesting once plants reach 6–8 inches tall
• Cut stems just above a leaf node to encourage bushier growth
• Harvest regularly for best flavor and continued production
• For strongest flavor, harvest before flowering

Common Problems

• Poor Germination: Seeds may be covered too deeply or lack light
• Leggy Seedlings: Not enough light exposure
• Overwatering: Can cause root rot
• Aggressive Growth: Needs containment or regular trimming

Final Tips for Success

• Do not bury seeds—light is essential for germination
• Keep soil moist but not waterlogged
• Start indoors for better control and earlier growth
• Use containers to manage spreading
• Harvest often to keep plants productive

Growing spearmint from seed is an easy way to enjoy a continuous supply of fresh, flavorful herbs. With minimal effort, Mentha spicata will thrive and provide abundant harvests throughout the growing season.