I start making new cuttings right about now for next years crop of coleus. Some varieties will root in as little as 3 days while others take a few weeks to provide viable roots. I have used rooting hormone on many different plants but have never needed anything other than a glass of water for coleus in a sunny window. I find that a sunny window is all it takes, but close proximity to a fluorescence light bulb works wonders in the winter. I have taken cuttings from family members during the summer and then presented them with "new" plants the following summer. They and I always find that to be a fun and money saving little gift. Each spring I always buy a few new varieties early and then cut them apart as soon as I get home to make 3, 4 or 5 new plants. My deck and I love them!