I currently have one in ground and another one potted. I will like to add another one right next to the one in ground but the largest I've seen are just a bit larger and wider than mine. I wonder if Amy of you could share pics of more mature Pickerings.
Here is my the in ground of course adorned by inpatients because she is the princess (I know I lost my mind). Followed by a dwarfed Glenn (that's another story) and a Carrie in the end.
And here is the potted one. Their growth habit seems different.
Sorry about the size of the pics I don't know how to fix it.