This USDA page may be of interest:
http://plants.usda.gov/plantgu...
They suggest planting it in a pot sunk in the ground to control spread by rhizomes. My late grandfather used to do that with mints.
Definitely a weed around here though, but it is pretty and gets an undeserved bad reputation with some allergy sufferers when they are actually being affected by ragweed not goldenrod. I even saw a well-known TV program show a picture of goldenrod in a piece about allergies, and labeled it ragweed!
