Hi there. Moss can be a bit difficult to get established, depending on the type selected and the amount of sunlight/moisture available. This moss is irish moss (sagina subulata), a type of moss that prefers full sun and well draining soil. There are other mosses that work better in shaded areas of the garden with wetter conditions. Without seeing the site conditions, I would guess that the moss didn't work out on your site because it wasn't getting sufficient drainage. This is usually when it turns yellow and dies off. Usually we purchase moss from the nursery, but it can also be purchased online at companies like moss acres (www.mossacres.com). Hope that helps.