It wouldn't work in my zone to plant them that deep. I think 2" is the recommended depth, I tend to barely cover mine & they do great for me. I'm a warmer zone, but I think that 2" over the root would work. I'd plant them asap since they have that growth, & cover them if you get a hard frost. They can handle a light frost fine at this stage. Or you can pot them up at the depth you want & plant out later. They are really pretty forgiving. You will love them, I have both of these & they are beautiful.

I have read 2 inches over the top of the roots, so the hole could well be 4 inches deep...Don't forget the "well-rotted-manure or compost..
Well drained soil helps, if not, raise the peony bed by several inches.

Thanks for your replies. Year back I planted one too deep, and never got any flowers. Now I'm waiting for the weather to warm up again! I have bagged compost, bought last fall. Will that work?