Genus Paeonia Species x Cultivar 'Bartzella' Common Name Bartzella Peony Patent ID Height 2 to 2.5 Feet Spread 2.5 to 3 Feet Habit Clumping habit. Rapid growth rate. Zone 2 to 7 Culture Full sun to partial shade. Flower Huge, double yellow flowers, with a red center. Blooms May. Flower Color Yellow Foliage Medium green foliage. Herbaceous. Category: Sun Perennial Description Beautiful hybrid of a herbaceous peony & a tree peony. Very unique.