The thing to remember about the tree peony, as I too need to remind myself, is that they get bigger
What started off as a space a foot or so high by 8 or 10 inches wide, becomes 4 feet or higher with a spread of 3-4 feet or more. The area where I have the two shown above, I used to have yellow rose shrubs in between the tree peonies, thinking that after the tree peonies would be done blooming I would have some color. Well, over a couple of seasons, the tree peonies decided that they owned the place, fighting the roses for the rule of the roost and winning out. Since then, I have placed clematis aside and behind and since they like to have their roots shaded, the tree peony provides that. They are nice companions. Or at least I am finding that it is something that works well. Lilies are another one that has survived the tree peony growth, though I have no idea how I would ever get a bulb out of that area if I wanted too.
So, I guess what I am saying is...with a tree peony, really provide it the room it needs to grow, it will use it in years to come
Thanks Chris for your kind words. The lavender-ish peony is quite nice. I think if it weren't next to the pink one, the color might not be as noticeably different, but it sure is. Just love those tree peonies!