The peony is beautiful in the spring and then just kind of hangs out all summer. Cool Splash has gorgeous leaves spring through fall. Both will be about the same size when they mature. Can you stagger them in the garden so both show? If so, I would put the peony more in the back and the Cool Splash more towards the front. Do you have room for a hydrangea in this garden? I have a white flowering hydrangea next to Cool Splash in my garden and it’s a beautiful combination. You should give it a try and let me know what you think.
Thanks for writing!