I’ve grown quite a number of peonies in pots, and grown them to the point where I’ll get herbaceous types with 3-4 blooming stems, growing in a #3 pot.

But these are peonies that I’ve grown from seeds, and potted them along to larger pots every year. As young seedlings, they seem to adjust their root systems to whatever container they are growing in just fine though. (I’ll keep certain special seedlings in pots, so I can bring them indoors during evenings of late spring frosts.)

However, I’m not sure how happy these plants would be if I left them in the pots for some years after their first blooms ? As was mentioned, it can be hard to tend them as well as we should either.

Nor do I think herbaceous types would do as well if they had been grown from large divisions to begin with ?

Having said that, I’ve certainly seen some very large intersectionals growing in pots at garden centers, and have always wondered if intersectionals may be more tolerant of this sort of treatment than herbaceous types might be ?