Last summer I tried some coleus in my partly shady window boxes. They performed so well I took cuttings in the late summer and grew them under lights.
The process of rooting cuttings is simple. Coleus are easy to root. I cut about 3 inches from the tip of the growing branches, Then strip the bottom leaves from the stem. I dipped the cut end in rooting hormone and placed it in a moist potting soil. The rooting hormone may not be necessary for coleus, as it is so easy to root.
Then it is important to keep the cuttings moist but not soggy, so I mist them and cover with plastic wrap. When I see the tips start to grow, I know they have rooted. It is time to transplant them to a pot when the roots have filled the cell pak. When pot is filled out, transplant to garden.