Moisture and heat are the main enemies of viable seed -- strong sunlight is inadvisable, too. Seed can be safely stored in airtight, well-sealed containers, either glass or plastic, with silica gel packets (available at many craft stores) to absorb excess moisture that may cause seeds to either mold or germinate prematurely. A few grains of dry rice or some powdered milk wrapped in a tissue can also help to absorb moisture. As a general rule, temperatures around 40ºF work well for maintaining long term seed viability, making a refrigerator the ideal storage facility. However, if you do store seeds in a refrigerator, do not keep them in the same compartment with fruits and vegetables. Some fruits (apples, for example) give off a chemical as they ripen that will inhibit the germination of many species of seed. Alternately, many seeds store quite well in any cool, dry, and dark location. Although some seeds require exposure to cold temperatures for a period of time in order to break dormancy, many others will not survive prolonged freezing, making a freezer a risky storage facility.
Be certain to mark any containers with basic information about the seeds: species, and when and where it was collected.
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