Most of mine I haven't had for a long period of time so it is hard to say which will really qualify as vigorous. Now there are several dwarfs I can say are extremely vigorous in their growth, but the TB's take longer to produce lots of increases. The only exception I have to that is Las Vegas, which goes out of it's way to increase, and bloom and re-bloom. A favorite? Not really, but it sure has stamina, and I respect that.
