Former graduate student Alem Peter’s (and current Syngenta employee) research on using controlled water deficits for height control of poinsettias was in the news recently. See the post from phys.org:

https://sitephys.org/news/2015-04-poinsettia-height.html

Poinsettia were grown to different sizes by manipulating irrigation. No chemical growth control was used to grow these plants.