Harvesting and Storing Nasturtium Seeds

Nasturtiums (Tropaeolum majus) are easy to grow from seed, and saving your own is rewarding—if you follow a few key rules.

When to Harvest

Never pick green seeds. Wait until the seed pods (which look like the seeds themselves) turn brown, beige, or blackish-brown and shrivel. They'll easily detach when mature. Collect before they fall and get wet or start sprouting.

Drying and Storage

1. Spread seeds on a paper towel indoors, away from sunlight, for a few days to ensure complete dryness.
2. Place in a labeled, sealed envelope or jar.
3. Store in a cool, dark, dry place—a closet or cabinet works well. Silica gel packets help absorb residual moisture.

Important Considerations

Hybrid vs. heirloom: Saved seeds from hybrids may not come true—offspring might revert to a parent form (e.g., spurless varieties developing spurs). Heirloom varieties breed true.

Germination Tips

Nasturtium seeds have hard coats. To speed germination:

• Soak seeds in water overnight, or wrap in a damp paper towel for 1–2 days before planting.
• Plant in pre-moistened soil.
• For early starts, sow indoors 3 weeks before last frost, or use the "bottle greenhouse" method: cut the bottom off a clear plastic bottle, press into soil 2 weeks before planting to warm it, sow seeds, cover with bottle (remove cap for ventilation), and remove once weather warms and leaves touch sides.

Nasturtiums tolerate light frost, so they can be direct-sown early in spring.