Hello Gardens 1948,
Not sure on the roting part but you could always cut the plant down to whre you would like it and root the top. Keep the bottom and let it branch out and you'll have a very bushy plant. Better to wait for the cutting and rooting till spirng though. Gool Luck :)
Sean

Hi,
If you are talking like on a tomato, where you take leaves off and take the trunk or stem down deep into the soil.
..no plumerias are flowering trees..put roots in and 3 or 4" trunk in soil.. If you want small plants, you would be better off to buy dwarf plumerias..stay smaller.

Karen B