Depends on what your definition of sharpen is. You are usually cutting into sand , gravel , and whatnot. Some people like to keep a good sharp blade but realistically just a crisp beveled edge makes more sense ultimately , for any digging tool. You will probably see some replies here by some who prefer to keep theirs super sharp so they can cut through stuff , but atleast in my opinion keeping a tool sharp that you use to cut sand seems more trouble than its worth. But I guess its just a personal preference , everybody does things a little different.