When and How to Plant Iris Seeds

Planting Time

Iris seeds need a cold period (vernalization) to break dormancy. Plant in the garden in fall (e.g., September) for natural stratification. Alternatively, stratify in refrigerator (damp paper towel in sealed bag) from January/February for spring germination.

Germination & Growth

• Seeds need 2+ months below 40°F (4°C).
• Seedlings resemble grass; keep bed weed-free.
• Blooms typically appear in 2nd or 3rd season.

Key Terms

Vernalization = stratification = cold treatment. The cold activates hormones that allow germination when warmth returns.