Can you post a picture?

I can later. Basically the sprouts get above ground then start withering

"I planted it into a whiskey barrel with miracle grow moisture control and kept the clay that the tuber was growing with."

That could have a lot to do with the problem.

http://www.missouribotanicalgarden.org/Portals/0/Gardening/Gardening%20Help/Visual%20Guides/Peony%20Problems.pdf

Check this out. It could be crown rot.

Another thing that may help, i dug one up and there was at least 6 or 7 sprouts under ground that were ready to come though. The problem isnt until they break through the dirt

@gardengal48 (PNW Z8/9) what would be your suggestion to try to repot it in?

Anything other than any Miracle Gro soil product, preferably something that is bark based rather than peat based. And I'd gently remove/wash away any remaining clay from the rootball.

any suggestion on store bought soils that would work?

Very few bagged soils - other than Miracle Gro - have a national distribution. Most are pretty regional. Pro-Mix BRK is about the closest you can find but may need to be special ordered. If Dr. Earth soils are available in your area, they also have some bark based potting soils. But check first...many of these will have too much peat and not enough bark.

this time of year i can usually get promix from lowes or any farm store ... home depot.. etc ..

a lot of peeps do mix it with bark mini chunks to increase drainage even further ....

https://duckduckgo.com/?t=ffcm&q=bark+mini+chunks&iax=images&ia=images

i cant tell if lowes bark is mini ...

https://www.lowes.com/search?searchTerm=bark+mini+chunks

ken

https://www.lowes.com/pd/PRO-MIX-Pro-Mix-2-cu-ft-Potting-Soil-Mix/3733135

btw ... the clay is not really the issue ... its either how you planted in your clay.. or how you watered in your clay.. that probably caused the problem ...

learn how to deal with your clay .. and how to make it better and in the very long run.. you will be much further ahead ...

i doubt you are going to be happy with all your plants in whiskey barrels ...

ken

There are a zillion different formulations of Pro-Mix but the PM BRK is not one that you will find carried at Lowe's or HD. And just adding bark chunks to the regular PM is NOT going to produce the results you want.

I usually blend my potting soil with pine bark fines or a 100% pine soil conditioner that we have locally. Much smaller than bark chunks.