While I haven't tried peonies myself, I did visit the Arnoskys near Wimberly last week -- they own of Texas Specialty Cut Flowers and sell about 60 varieties commercially. They told me that peonies were one of the flowers they'd tried but not managed to have success with.
I figure if THEY can't grow them here, nobody can.

Boo-hoo

I put a plant in and I'm hoping it will do okay. So far today it looks like this in a bed that gets some direct, dappled and shade during the course of the day. The roots I planted aren't expected for another two years but are growing fine in the ground and pots around my El Paso yard.

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Wimberley, Texas

I planted one Peony 10 years ago in my flower garden. Each year she would come up and reach the height

of one foot but no buds. This spring due to the rain and cool evening temp she grew to 2 feet and produced 2 buds.

It took the buds 1 month and they opened the past four days. They are a soft, soft pink in color, approximately 4" wide and the aroma is a soft sweet pink! Just like you would image pink to be. All the neighbors have been down to witness the opening. I believe I have the only Peony Blossoms in Wimberley, Tx. It was certainly worth the 10 year wait.

rr12lackner

Wimberley Peony May, 2015

Why not grow tree peonies ? which are easier for Texas.