Silica Gel for Dry Seed Storage

For long-term seed storage in humid climates, dry the seeds very well first, and then seal them tightly in glass or plastic tubs or jars. Ideally, stored seeds should contain 3-5 percent moisture in a Relative Humidity around 20%.

Buy silica gel desiccant from a craft store flower-drying aisle. Put 1-2 tablespoons of silica gel into a paper coin envelope and staple it several times or tape it closed.

Keep the desiccant in a sealed jar and don't open the jar more often than necessary. Replace the desiccant 1-2 times per year if you open the jar once or twice per month.

It can be regenerated in an oven at 250 degrees F. Don't use higher temperatures because silica gel loses some drying capacity if "scorched".

If you don't have silica gel, bake some rice just short of browning it, to get it extra-dry.

Keep a slip of newsprint in a jar to see how dry it is: if the newsprint doesn't crackle when you bend it, or if it feels limp instead of crisp, it is too humid for ideal long term seed storage.

• Zinnia
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