what part of the leek do you use for soup

When making leek soup, you should use only the white and light green parts of the leek. The darker green parts of the leek are tougher and can be stronger tasting, but they can be used to make homemade soup stock or cooked longer to tenderize them. Some recipes for leek soup call for just the white part of the leek, probably to keep the soup a paler color, but the greens have just as much flavor and can be used as well. However, some sources suggest that the dark green parts of the leek should not be used in soup. Ultimately, the part of the leek you use for soup depends on your personal preference and the recipe you are following.