To do both you would need to separate and put in their own pots. That pot is not big enough for the peony to grow to blooming size.

Thanks maifleur. The lobelia usually dies and is hard to transplant. Plus, I believe peonies don't like their roots disturbed. I know that a lot of people are uses to large containers but as someone growing too many things on a 15X5 condo balcony, I try, often successfully, to grow things in smaller containers. I have seen peonies blooming in 2 gallon pots in nurseries. I am going to wait till its roots demand a bigger pot. I am probably going to keep moving the container in and out to keep it from freezing. I just don't have the heart to sacrifice the lobelia.

Since the only way to have a named variety of herbaceous peony is to dig it up from the ground and unless it is something like the original Sarah Bernhardt peony cut it apart into root sections the idea that peonies do not like their roots disturbed has always seemed laughable to me. The original Sarah Bernhardt if you drop the dug clump on the ground will break apart in natural divisions but most you need to take a knife or saw to.

If you could keep it above 32f but below 40f you could probably leave it alone.