You can freeze parsley as individual leaves, or in ice cube trays using water or oil. Most sources, including Livestrong, recommend freezing clean, chopped parsley in ice cube trays half-filled with water or oil, depending on how it will be used later. You can use frozen cubes in cooked dishes.
If preferred, parsley can be frozen as individual leaves. Once removed from the stem, leaves should be spread in a single layer on a cookie tray and frozen. Then the leaves can be placed in a Ziploc bag for future use. Other fresh herbs, such as oregano and basil, can be frozen in the same way.