I've read many times that the large and giant varieties are the last to bloom. I don't necessarily agree with that, maybe on average. But Fleurel, Kelvin Floodlight and Alfred C are among my first dahlias to bloom every year. There are a few more bigger ones that usually aren't far behind. But there are several factors that can influence early/late blooming, like weather, fertilizer and the quality of the tuber or clump.
