Plumeria can be rooted by planting the cutting in a good soil mix and a little basic care, but you get the best results by first callusing the cutting.
Callusing protects the cut end and leads to faster and stronger rooting with less possibility of losing the cutting due to rotting. To get a good callous I use a humidity box that can fit 4 to 5 cuttings.
A clear plastic storage box works well because you can generally see what is going on inside the humidity box during the callusing process. This allows you to check moisture content as well as when the callous appears without opening the box. This box is 12” long by 10” wide by 6’ high. The wetted moss will be the source of humidity and the ¾” X 9 ½” PVC tubes will be what the cuttings rest on to keep them from touching the damp moss.
Place your cutting(s) on top of tubes and place the box in a warm and shady area. Cutting(s) take about 3 to 7 days to become fully calloused. When callous is observed, remove the cutting(s) and pot immediately.