I've got better success with sending the plants with damp paper towels, not wet nor with water; double bagged with just enough air to cushion the plants, in a bubblewrap-lined envelope with cardboard stiffeners. I've tried sending emerse cuttings and rhizomes dry but they came a little worse than those shipped damp. They re-hehdrated right away after bing put in water. I bag half of each species (each species is bagged into two ziplocks) before putting them all in a big bag. It may seem a lot of work but even if a few of the plants go bad, the others don't get fouled by the rotting plants and the plants are well insulated from temperature extremes and mechanical handling and compaction. They arrive ok even after 10-11 days of travel.