Delicate produce like salad greens can remain fresh for several weeks with Shirley's storage method: Soak the greens in cold water for 10 to 30 minutes to ensure that the cells are fully hydrated. Spin the greens in a salad spinner to remove as much surface water as possible then wrap in one or two sheets of dry paper toweling and place in a zip-top plastic bag. Squeeze out as much air as possible before sealing the bag, which is the key to keeping greens fresh for several weeks.