To ensure that seeds wake up refreshed from their long winter naps, take the time to tuck them in properly. Moisture, heat, and fluctuating temperatures are a seed's worst enemy, so don't simply abandon your leftover packets to the elements by leaving them in a garden shed. By the next spring they will have lost much of their vigor -- the ability to germinate quickly and healthily -- and many may have died. Instead, place packets in an airtight container, such as a canning jar with a new lid. Then make a few moisture-absorbing sachets to store with them by wrapping 2 tablespoons of untreated cat litter (avoid colored or scented litters) or powdered milk in a double layer of tulle. Close the lid tightly, and put the jar in a cool, dark place.