you can root costs by the 'buried cane' method: strip off any leaves on the stem, cut the stem into pieces each with a leaf node, bury the stems halfway in a shallow tray of soil, water lightly, and leave them for a bit. New plants will start from the leaf nodes where the old leaves were. Or, throw them on an open air compost heap if its warm enough where you are and cover them lightly with the plant litter, come back in a few weeks, and there should be new plants starting. You can then dig these out and pot/replant them. That is what I do with mine.
