Remove from the oven, and hang ears in a cool, dry place for 1-2 weeks. Try popping a few kernels before storing them, to assure they are dry. Dried kernels can be stored on the cob, or you can remove them from the cob for storage. To remove them for the cob, rub two dried ears against each other.
How to Dry Corn for Popcorn. Pick the ears of corn only after the kernels become hard and the husks turn dry and papery. Pull the husks off the ears and discard. Heat your oven to 300 degrees Fahrenheit for 20 minutes and arrange the ears in a single layer on a roasting pan. Leave overnight to dry the ears.
Allow the popcorn cobs to remain on the stalk as long as possible until the kernels and husks appear dry, but pick the corn and dry it artificially if rain threatens.
Martha Stewart prepares popcorn directly from the cob.