This grower is sure of this plant identification.
The plant for sale is a division of the photographed plant taken last autumn and starting to grow now. It is a large double red flower. The plant is very hardy having been out all winter with no protection.
Common peony, Peony
Paeonia officinalis (Common peony). This species has deep pink or scarlet petals with bright yellow stamens. The flowers are saucer-shaped and large they appear on solitary stems which are deep green. They will require fertile soil that has been deeply cultivated and amended with compost or well-rotted manure. Grow in full sun with some shade.
They will grow well in climates with a cold winter. They need a sheltered position in full or slightly filtered sunlight and moist soil. You will need to propagate from seed, or by division.
Border, wildflower/meadow, cutting bed, ground cover