Changes in flowering time and its regulation by environmental signals have played crucial roles in the evolutionary origin and spread of many cultivated plants. Recent investigations into the genetics of flowering time evolution in the common sunflower, Helianthus annuus, have provided insight into the historical and mechanistic dynamics of this process. Genetic mapping studies have confirmed phenotypic observations that selection on flowering time fluctuated in direction over sunflower's multistage history of early domestication and modern improvement. The FLOWERING LOCUS T/TERMINAL FLOWER 1 (FT/TFL1) gene family appears to have been a major contributor in these adaptive shifts. Evolutionary and functional investigations of this family in sunflower provide some of the first empirical evidence that new competitive interactions between recent gene duplications can contribute to evolutionary innovation. Notably, similar results in additional systems that validate this hypothesis are now being discovered. With a sunflower genome sequence now on its way, further research into the evolution of flowering time and its regulation by environmental signals during sunflower domestication is poised to lead to additional, equally important contributions.