How old does a Peony plant have to be before you can divide it?
How Old Does a Peony Plant Have to Be Before You Can Divide It?
Certified GKH Gardening Expert
It is not so much about age, but rather the size of the plant. If it is getting too large for the area it is in, then it is ready to be divided. If it has been in the ground for a few years, and you want to share with a friend, it should be big enough to divide as well.
But, I will warn you, peonies hate to be moved or divided. When you do this, it normally takes 1-3 years before they will bloom again.