The Royal Trumpet mushroom is typically harvested when the stems reach a length of several inches, but they can grow to a length of 6 to 8 inches. Depending on the type of storage provided, the flesh may darken or turn slightly tan or brown as the mushroom ages, but the quality is usually not affected.
When preparing Royal Trumpet mushrooms, a number of cooking methods can be used: braising, broiling, grilling, sautéing, or stewing. The mushrooms are often added to soups, stews, sauces, pasta, vegetable dishes, meats, and seafood. When prepared whole, the size of this meaty mushroom warrants a longer cooking time than smaller varieties. To store the mushrooms properly, place them in a paper bag and refrigerate. When stored in this manner, Royal Trumpets should be used within ten days.