I have never had much luck with peony root cuttings. When you dig and divide a large peony root several root sections often break off. I have tried to start them as the bulbous root is storing a lot of energy, but have not been able to start them growing. Al

To:calistoga
Er¡­I've known it's quite difficult,anyhow,Thank you!However,there is another question:
Have you ever tried to use any plant hormone such as NAA or IBA to deal with the root segments before root cuttings?

No I have not used hormone on peony roots. Next time the occasion arises I will try Mycorrhizal fungi which may help the roots to grow, but I think the real problem is a lack of adventitious buds. Al

Aha¡­VAM!Maybe it's a good idea!Wish U luck first!
Several weeks ago I also learnt a little about tree peony's AM which help two-year seedlings root well.
By the way ,has mycorrhizal fungi of peony already been abstracted? Or,U just plan to use some ordinary fungal fertilizer?
And are U a student or researcher of peony studies?

On rare occasions where I believe it may help a root system take up nutrients and enhance the growth of feeder roots, I will use a Mycorrhizal inoculation on the bare roots as they are planted, not specifically on any type plant. There are hundreds of different Mycorrhizal fungi and their use is a gamble which will do no harm but also may do no good. Al