Spore print storage: how long do they actually last and how to maximize longevity

For anything less than 2 years: sealed in foil or paper, dark, room temperature or refrigerator. Refrigerator extends viability somewhat. The enemy is moisture, not temperature (at reasonable ranges). For 5+ years: freezer in an airtight container with desiccant, wrapped in foil first.

The moisture point is crucial and often missed. Condensation when removing cold-stored prints is a spore killer. Always let cold containers come to room temperature before opening them. This one step prevents the majority of long-term storage failures.

I've successfully germinated prints that were refrigerated for 8 years. The rate drops and you may need more inoculation volume, but aged prints can still work. Frozen prints I've had success with at 4 years. Beyond that, convert to liquid culture for safety.