When I get a new appliance or anything with a warranty, I write the expiration date of the warranty on the box in permanent marker and my husband stores the empty box, with the packing materials inside in the garage.  He checks the boxes every so often and recycles the boxes that the warranty has expired.

This way, if something goes wrong during the warranty period, we have the original box and packing materials to return the item. Since most warranties are only 90 days, the boxes do not stay long in the garage.

Save box until warranty expires.