| Water rooting always works but keep an eye on the water souring which will lead to rot. It is very easy to root canes in some "good" potting soil and keeping the soil moist (Not soaking wet). Cane begonias should root in a week or two. For canes with several nodes you can lay the cane horizontally on a bed of perlite or good potting soil. Keep moist as above and new canes should emerge at most nodes. | 
