Sep 11, Don't toss out your used coffee grounds just yet! #1 – Dry the grounds out on a cookie sheet and then put them in a bowl in your refrigerator. Sep 10, Learn how to store used coffee grounds so they don't mold and how to reuse them. is cold in the winter, going out to the composter may not be an option. Simply allowing the ground to dry on the countertop doesn't work. Apr 17, Used coffee grounds do not store too well due to their high water content; Here we have a video of drying out grounds without putting them.