Growing Peonies in Pots
A question I'm often asked is, "Can I grow a peony in a pot?" And the answer is, it depends on why. Are you going to hold your peony temporarily until you can transfer it to an in-ground home? That's an unqualified yes.
For the first year of a peony's life, its root system is small. During the second year, it may double in size. But after the third year, the root system will be a prodigious mass indeed. That means you have a little time. So perhaps you'll be moving to a new home in a few months, and you want to hold your plant until you can plant it there, you should be just fine.
A peony will always be happiest in the ground. But if you're still planning to hold your peony in a pot permanently, you'll need to strategize. Again, after the third year a peony root quickly becomes massive. It's on its way to becoming up to three feet across. What can you do?
Some strategies for growing a peony in a pot:
-Choose a smaller variety. Many landscape varieties are listed as being 24" tall or so at maturity. These will have correspondingly smaller roots.
-Provide a huge pot from the outset.
-Plan to repot as the peony grows.
-Plan to divide the plant when it outgrows the biggest pot you're willing to give it. Remember that peonies are unlikely to bloom for a couple of years after dividing.
All the rules of planting peonies in the ground apply, with the most important considerations being drainage and planting depth. Pots tend to dry out more quickly than in-ground plantings, so be sure to monitor moisture levels.