Antique Corn Kernels
The lifespan for seeds is determined by the kind of seed at hand, also the conditions under which it is stored. Suggested is cool and dry, which is generally 50 degrees, at 50 percent humidity. The goal is to maintain an acceptable percentage of seeds alive and able to germinate when planted. Under such conditions, the lifetime for sweet corn is expected to be 1, perhaps 2, years.
Even so, some seeds will survive longer than average estimates. Gardeners can do a simple germination test to determine what percent of seeds will grow. The basics of the test are to roll 10 seeds in a moist paper towel, enclose that in a plastic bag, then wait 2 to 5 days. After that, check to see how many seeds sprouted. All the details are in “How to test your stored seed for germination” http://extension.oregonstate.edu/gardening/how-test-your-stored-seed-germination-0