There are 1000's of varieties and cultivars available at retail nurseries or plant catalogues where you can while away the afternoon choosing your perfect Dahlia. The Dinner Plate Group have as the name suggests huge flower heads, but there are dwarf cultivars up to 2 ft. tall
Summer-fall
Full sun
Water regularly once established to keep soil moist, about 1-3 times a week
Prune to 3-5 flowering stems
Dahlias will not survive freezing temperatures
Zones 8-10
Plant tubers late May-June
Try a loamy, sandy soil
Depends on variety