“ Grafting is the best means of reproducing a brand new clone of an existing tree peony variety.
That is an historical approach whereby the bud of the desired selection is fused onto
an beneath-inventory of either tree or herbaceous peony root.
Considered one of the principle reasons tree peonies remain expensive plants is
that grafting, a labor intensive and slow process, remains the simplest means of asexual propagation, or cloning.
Tree peonies reportedly may be rooted from summer time cuttings (Source!), however success requires humidity and temperature to be carefully managed.
This is very troublesome and never completed in any production setting we're aware
of. There have been some reports of success in cell tissue micropropagation of tree peonies, though massive-scale success has so far proved
elusive. Age-outdated grafting methods are the preferred method of propagation of tree
peonies in Japan, China and the U.S. Grafting will stay a necessary ability for gardeners to propagate woody plants, as it has been for centuries. ”