When mosses first dry out, they don't die right away; they simply turn brown and go dormant. They can stay like this for various lengths of time before they must be rehydrated, depending on the species. One variety, Anoectangium compactum, can survive an incredible 19 years without water. It is not common for moss to die, so always try thorough watering first. However, if your moss plant death does occur, remove all the old moss from the pole and start over or if you can spare the extra money to create a new pole, you can throw the entire moss pole away and start over.