When saving corn seeds, you'll need to start with an heirloom variety of sweet corn. One of the more common heirloom varieties is Golden Bantam, which dates back more than 100 years. There are other heirloom sweet corn varieties available from many different seed companies and catalogs.
Once you know you have an heirloom variety, the next step is to harvest
the seeds (kernels). It's best to allow the ears of corn to dry and
mature while still on the stalks. As soon as the ears are dry and the
kernels have hardened up, remove the ear from the stalk. You don't want
to wait too long because a heavy rain can cause mold to develop.
Additionally, the longer you leave the corn on the stalk, the more
chances of ants or other pests getting into the kernels. You have to
walk a fine line - leave the ears on the stalk long enough to dry, but not so
long that something happens to them.
Once you've harvested the dry ears, go ahead and remove the husks and let the kernels finish drying in protected location like a garage or shed. The kernels will turn hard when they are completely dry and you should be able to rub them off the ears with the palms of your hands.
You can then put
the seeds inside an envelope and store them in a jar in your
refrigerator. Make sure you label the envelope so you know what seeds
it contains. If you are saving lots of different seeds, several
envelopes can fit inside one, quart-sized jar. It's also a good idea to
put a tablespoon of dry rice at the bottom of the jar just to absorb
If you're saving corn seeds, it's a good idea to harvest seeds from at least 100 different corn plants to avoid inbreeding and keep your seed population strong. Ideally, harvesting seed from 200+ plants is even better. If you harvest from too few plants, the genetic base narrows and subsequent crops will be less and less productive. If you aren't able to collect seed kernels from enough plants, consider mixing them with another batch of seed corn that you've previously saved or that you get from a another grower.
Click on the following links to learn more about growing sweet corn.