Rick, your post was enough to push me over the fence onto the side of not planting it. Thank you for the warning.
Granted, chicory is already everywhere around SE Michigan, but I don't want it to get into my neighbors' yards because, fortunately, it isn't something that seems to grow in the residential neighborhoods around this area yet.
I'll stick with my vivid blue "Summer Nights" delphinium, if I can get them to quit dying on me.