When planning your spring or summer garden, usually during the late winter, it's time to check your old seeds for signs they will still grow. Few gardeners use an entire seed packet in one year, and many seeds take years to use. While many seeds last for several years when kept in the right conditions--a sacred lotus seed (Nelumbo nucifera) sprouted after storage for 1,200 years, according to the Brooklyn Botanic Garden--some seeds have a limited life span regardless of storage conditions. Yet it's always worth verifying a seed's ability to sprout before tossing it.
Check seed expiration dates or "packed for year" dates printed on most seed packets. With proper seed storage, cool and dry conditions, they last longer. Corn, onions and peppers have the shortest life span at one to two years. Beans, beets, cabbage, carrots, squash, eggplant and tomatoes usually last three to four years. Cucumbers, lettuce, melons and spinach typically last five to six years.
Conduct a germination test on seeds more than a year old. Place 10 seeds on a damp paper towel. Place into a plastic resealable bag and seal. Print the date and seed variety on the page with a marker.
Set the bag somewhere in your home that maintains a consistent room temperature for a week. After a week check the bag and count the number of seeds that sprouted.
Choose which seeds to plant and how to plant based on germination rates. If eight to 10 germinate, plant as usual. If six to seven germinate, sow thickly in the garden when planting. If five or less germinate, throw away the seeds.