Hi and welcome to ATP
Here's the entry from our Plant Database that came up when I searched for Rudbeckia Goldsturm.
Black Eyed Susan (Rudbeckia fulgida var. sullivantii 'Goldsturm')
It says they get 2 to 3 ft. and that Goldsturm are indeed fulgida - or the other way around. Sorry, that info's not a whole lot of help. All I can say is gardening is an inexact science at best and plants have minds of their own as to how tall they will get to be. Let's just say if you buy big transplants in gallon size pots now, they might be 2ft. tall in late August when they will really start to bloom, and 3ft. tall in September when they are in their full stride. (it's a little late in the game to be starting tall perennials, needless to say)
