Japanese Tree Paeonies really are on of the most majestic garden plants you can grow. When in full summer flower their huge papery flowers will smother the tree.
Depsite their fine foliage and paper-thin flowers, they are very robust and very hardy, and suprisingy easy to grow - although patience helps too, as they can be slow to really get going for a year or two after initial planting.
Modern varieties are grafted, and all produce their classic huge flowers, up to 20cm (8') across in late spring and summer. Plant sraight into deep, well-drained soils (avoid growing in pots for best results), they are fairtly fuss free, and will produce flowers from 2-3 years time.