Wet potpourri, which refers to potpourri created with moisture from fresh flowers and botanicals, can last anywhere from one week to a couple of months. Its longevity will depend on the ingredients, the freshness of the botanicals, and how well they hold fragrance. Wet potpourri is more susceptible to mold, so you should check periodically for any signs of spoilage. To prolong its life, store it in a well-ventilated container and refresh the scent by adding new fresh botanicals or essential oils when needed.