Marshmallows lend themselves to freezing since their sugar content acts as a preservative, and they can be frozen for up to three months. You can store an unopened bag of them in the freezer, but dividing them into small clusters and wrapping them in plastic wrap or foil will keep them fresher. This prevents ice from forming between the candies, which makes the marshmallows soggy when they thaw.
Divide the marshmallows into small groups. For large marshmallows, separate them into piles of six. For miniature marshmallows, make piles that contain 6 tbsp. of marshmallows.
Count how many piles that you have, and tear that many sheets of plastic wrap or aluminum foil from the roll. (If, for instance, you have 10 piles of marshmallows, tear off 10 sheets of aluminum or plastic.)
Sit a pile of marshmallows on a corner of each sheet of freezer wrap. Roll the wrap into a tight ball around the candies, starting at the corner where the candies sit.
Place the wrapped balls of marshmallows in a plastic container with an airtight lid, and seal the container shut.
Tear off a piece of masking tape. Print "marshmallows" and "use by" and the date that is three months in the future on the tape. (So if the date you packed the marshmallows is March 1, print "June 1" on the tape.) Stick the tape on the front of the container.
Sit the marshmallows next to similar items in the freezer -- like ice cream, desserts or other candies -- to make them easy to locate when you need them.