One way to freeze parsley is to pack parsley leaves into a freezer bag and roll it into a log to remove air before placing it in the freezer. Another option is to place chopped parsley into ice cube trays with a small amount of water to freeze.
To freeze a log of parsley, rinse and thoroughly dry the parsley leaves. Remove the parsley stems if necessary. Fill a large freezer bag with as much parsley as you can and lay it flat. Starting from the bottom, slowly roll up the bag tightly, removing as much air as possible and creating a log shape with the parsley at the bottom of the bag. Seal the bag shut and secure the log shape with rubber bands before storing in the freezer. To use the parsley later, remove the log from the freezer and slice off just what you need.
To freeze parsley in ice cube trays, chop it up and place about one or two teaspoons into each compartment. Top off each compartment with water and place the tray in the freezer. Once the parsley cubes are frozen, pop them out of the ice cube trays and store them in a large freezer bag. Parsley frozen in ice can go directly into hot soups and sauces. To use them for other purposes, allow the to cubes melt in room temperature water, then strain the parsley with a fine mesh strainer.