: You can carefully divide the tuber "cluster" vertically down through the stem, taking care to keep a portion of the main stem with each tuber, preferably after the plant starts shooting so you get 1 or more new shoots on each division. Or I have never heard of dividing the cluster through the stem to propagate a dahlia I understood that you had to examine the tubers of the cluster looking for an eye and then that tuber , detached ,would grow a new plant. I am doing them from seed right now. I have Fireworks blooming from seed and somewhere amongst my thousands of plant sI probably have the Collarette variety and cactus flowered as well.