Arugula lasts longer if harvested with roots, wrap the stems in a moistened paper towel and place in a plastic bag in the most humid area of the refrigerator (usually the vegetable drawer). Keep loose leaves in a plastic bag. Arugula tends to be gritty, so rinse the leaves thoroughly. The greens can be stirred into pasta and scattered on pizza. Arugula is at its best in salads: Drizzle it with extra-virgin olive oil and lemon juice and top with shaved Parmesan, salt, and pepper.