Pick out the ears you plan to use for seed while the stalks are still growing. If pests are a problem, put paper bags over the ears. Choose stalks that look vigorous with ears that seem well developed.
Wait about four to six weeks after picking your "eating corn" before you harvest the seed corn. Make sure the harvest takes place before the first frost.
Harvest the ears and remove the paper bags.
Strip the corn down to the cob's base but do not remove the husks.
Hang the ears in a place free of drafts, moisture and pests. Several ears can be bundled or twisted together by their husks.
Keep checking until the corn is completely dried out; the process usually takes at least two months. A properly dried kernel of sweet corn will be quite wrinkled.
To remove the seed, hold each ear over a bowl, twist with both hands, and shell the corn.
Pick through the seeds to weed out any that aren't the same color as the others, or that don't look properly wrinkled.
Store the seed in paper bags in a cool place until the next planting season. The refrigerator's crisper drawer is ideal. Alternatively, store the seed in glass or metal canisters.