If your peony is dormant this is a good time to do it. Depending on size and age this could be heavy dirty job and I would suggest you have help available. There is no secret, just dig around the plant allowing plenty of room for a large root mass. If you have help you should be able to move it intact. Al

It's still has leaves on it now. From your post - I should wait until it loses it leaves.

If the leaves have turned go ahead. A well established tree peony would do OK now in any case. I have been told that frozen ground is tough to dig! Al

macbth,
Than later than better.
I have to transplant a 6 y/o tree peony as well, but I'm waiting untill it become leafless=dormant. By the time when it happens grounds will be not frozen yet.

ego45
I plan on taking your advise- I will wait for the leaves to fall off, then transplant the Peonies. I am just wondering how long after the leaves fall off to make sure that the plant is dormant?

Falling leaves would be your indication of a state of dormancy/almost dormancy.
In either case it will be OK to transplant at that time.

This maybe one of the most valuable ($) plants in your garden proceed with care. A three year old tree peony would cost $50.00+ to replace. Van Bourgondien is a good source for these plants should you have a problem.