The history of flower breeding, discovery of genetic laws and their co-integration in early floricultural breeding programs led to an amazing array of seed- and vegetative-propagated ornamental floricultural crops for the worldwide market. While most early genetic research used flower crops as study organisms, the genetics of edible grain crops soon held sway. This chapter reviews advances in molecular breeding of ornamental plants. It begins by discussing how flowers can be used as study organisms for early genetic research. The chapter then reviews flower breeding in the 19th and 20th centuries and goes on to discuss the early use of biotechnology in marker-assisted breeding. It also provides sections on flower color and flowering genes, as well as providing an analysis of genetically engineered flowers such as GMO carnations, roses and chrysanthemums. A review of genome sequencing and gene editing is also provided, before the chapter concludes by highlighting future areas for research and other sources for further information.