Science is now a tool for artistic expression like it has never been before!
True blue requires complex chemistry. Anthocyanins—pigment molecules in the petals, stem, and fruit—consist of rings that cause a flower to turn red, purple, or blue, depending on what sugars or other groups of atoms are attached. Conditions inside the plant cell also matter. So just transplanting an anthocyanin from a blue flower like a delphinium didn’t really work.
LINK: http://www.sciencemag.org/news/2017/07/scientists-genetically-engineer-world-s-first-blue-chrysanthemum