Checking back in. My non-blooming tree peony remains barren. I think it is going on 6 years now. A bit taller and wider than my photos above, and still no signs of blooms. I have not fertilized it at all. It is sited in a corner with southwest exposure so plenty of sun. Healthy as can be. I've about given up on it as a flower and simply treating it as a nice foliage plant.