I have one that I planted in 1996. It measures 3'9" at its tallest and 6'5" at its widest. I don't water much and I never fertilize. Its in sun till around 3pm then shade. Great plant, though I may remove some suckers this year to reduce the spread a bit.

Wow! So who makes up these height and width "maximums" anyway? Or is it just an average?

Just to be sure there is no misunderstanding, "one" as I used it, means a colony of suckers around the parent plant.

It doesn't grow tall but it does slowely get wider. It suckers but its not as if its going to take over as it spreads very slowely. Its a great plant and smells divine when it blooms.

Ok, so the key is to get rid of the suckers if I don't want it to spread width-wise. Thanks!