I'm compulsive about keeping seed records, and record my findings on my website. For many species, I have records for the same seed lot over multiple years, and you can watch how it goes down year by year. For example,
http://www.robsplants.com/plan... (seed-starting details near bottom of page). While many seeds don't have much more than a year of life in them (and some less), I'm amazed sometimes at how long they stay viable!
