Depends on what you want out of your peony. If you want a chance of it blooming next year I wouldn't divide it. If you want multiple plants of the same type and don't care if you have to wait a year or 3 for flowers, absolutely! There was a post from early this spring about Itohs being pretty good dividers, even a single stem w/root. I got the below link from it (kousa, look for a post, 2nd page from June title How to propagate stem of intersectional peony? ), seemed to be some really good info. Look under the Experiments tab. I added it to favorites because it had quite a bit of good info.
Good luck with your new peonies!

Here is a link that might be useful: Southern Peony Blog

Wow thanks LizinElizabeth. I want some bloom next year. I guess I'll just plant it as is. I'll order some bareroots this fall. I would like to have varieties of peonies in my garden. So far we have have 9 varieties of hydrangeas and 6 verities of peonies.

Take a look at the root ball when you take it out of the pot. If there's a small piece that detaches easily from the side maybe you can have both! I've seen posts where people advise you to let the divided edge dry out for an hour or 2 before planting to avoid disease so be careful of that if you do decide to divide at all. If not, a 3 gallon potted Bartzilla should be robust enough to BLOOM like CRAZY next spring! Congrats on your find!

I hope it bloom next year as well. I'm very excited. It actually in a 5 gal pot. The shirley temple and the maxima festiva are the ones in 3 gal pots. I'm not splitting those because i got 4 each already.

Also, does Barzella like full sun on partial shade? I read that they prefer partial shade.

I don't have a Bartzella that's big enough to bloom. Do have 2 Singing in the Rain's, 1 in part shade and 1 in full sun, the full sun one is much bigger and had several blooms last spring, shade one only had 2. I've never heard of any Itoh preferring light shade but I'm certainly not an expert. Don't know how many truly dedicated Itoh growers are still looking at the forum, you might want to contact Calistoga or Kousa via member mail. They seem to be very knowledgeable.

hi Joopster. I am not by any means as knowledgable as Liz made me sounds but I am glad to help if I know from my own growing experience or read from expert growers their experiences. From what i read about Bartzella, you get more flowers if you plant it in full sun than in shade. I only have one growing experience with Bartzella so i cannot really say how it performs in full sun or shade but I have mine in full sun. It gave me two flowers this past spring.

Thanks Kousa and Liz. I will plant my in full sun. I wish I have 2 so that I can experiment but they are kind of pricey. Thanks again to both of you.

Hi Joopster. If your potted Bartzella is a large one, by all means split it in half and plant in two locations. Bartzella is a very robust plant. In fact, you may get more flowers if you split in half because there is less competing roots and by doing so may stimulate more hairline root growth since the center part of the root ball is now exposed to soil.

Good advice, Karen! Wish I had one big enough to split, mine's still tiny....Maybe in a couple of years...How's that Petite Elegance doing?

Hi Liz! My Petite Elegance is doing OK. My cherry tomato plant is overtaking this space and the peony is currently hidden under the canopy of this gigantic tomato plant. I guess I underestimated its growth and planted too close to my peonies. I have given it some fertilizer after it bloomed so hopefully that will help it to form more roots and eyes for next year. I hope next fall I would have a good sized root to trade with you. How come your Bartzella is still small? How small was it when you bought it?