Unless it is moss I put the plants in an old fish bag with no extra water and either rubber band the top or knot it. I usually put enough air that the bag can't be completely pushed down. I don't use any extra water or wet paper towels because it remains pretty humid in the bag. I use newspaper or a grocery bag to take up the extra space in the box. If it is moss I put it in a small ziplock bag with some water then I suck all the air out so it is a flat little package and water covers all the moss.