Seed Viability Chart

Did you know that seeds vary highly with how long they'll keep before becoming unreliable to plant?  Some seeds, like cucumbers and melons, can keep for up to 5 years, while others, such as onions and chives, will only keep for one year.  How you store them also plays a role in their ability to sprout over time.  Cool and dark is the rule of thumb.  Here's a link to a handy chart listing storage viability for different seeds.