Why must seeds be completely dry before storage?
Written by
Olivia Mitchell
Reviewed by
Prof. Martin Thorne, Ph.D.It is essential to ensure that seeds are dehydrated before storage in order to maintain seed viability. Residual moisture enables biological processes to occur within the seed, allowing it to utilize its resources rapidly. I lost every zucchini seed from the last batch due to mold that developed because they were not completely dry beforehand. Proper drying will prevent destructive enzyme activity from occurring.
Moisture Targets
- Dormant seeds require under 8% moisture content for safe storage
- Test with moisture meters or the snap test for accuracy
- Seeds should feel brittle and break cleanly when bent
- High moisture triggers respiration depleting energy reserves
Drying Techniques
- Spread seeds in single layers on breathable screens
- Use dehumidifiers in humid climates for faster drying
- Avoid ovens which can overheat and damage embryos
- Rotate seeds regularly for uniform air exposure
Colored mold will begin to colonize within a few weeks of inadequate drying visibly. The fungal growth begins to consume the embryos within the seeds while producing mycotoxins that kill. I noticed some fuzzy white mold on the sunflower seeds that had not dried properly in just three weeks. All of this damage is irreversible and completely compromises the germination potential.
Ensuring storage dryness with a desiccant system is simple. Silica gel packets will absorb the majority of bad airflow and eliminate any excess moisture in closed containers. For lower-cost options, consider using rice, clay, or clay beads. I like to replace the silica indicators with new ones about every six months to ensure reliability and protection against moisture in storage containers.
Evaluate dryness without equipment or special tools using everyday techniques. Bend some larger seeds (such as beans) to see if they snap, not bend, and shake pepper seeds in a jar; listen for a loose sound, not a clumpy one. My snap test never fails to fully determine if your seeds are at the right moisture level.
Read the full article: 10 Best Seed Storage Containers
