Effective garden seed storage methods include keeping them in their original envelopes and putting loose seeds into plastic storage containers. Storing seeds in a refrigerator or cool, dark cabinet prolongs their shelf life.
Loose seeds benefit from storage on top of a moisture-absorbing substance such as raw rice or powdered milk. One way to do this is to cover the bottom of a plastic container with rice or powdered milk, cover the material with a paper towel, and then scatter the seeds on top.
Seed shelf life varies greatly. Some plants such as cucumber, calendula, radish and nasturtium remain viable for up to five years. Others, such as onion and geranium, only tolerate one year of storage.