Itoh Peony 'Julia Rose'

Peonies are popular garden plants with both herbaceous and tree peonies available. But there’s also another peony you can grow – hybrid peonies. Continue reading to learn more about Itoh peony types and growing hybrid peonies.

What are Itoh Peonies?
In the early 1900’s, plant breeders scoffed at the idea of cross breeding herbaceous peonies with tree peonies; the species were considered too different and incompatible. In 1948, after thousands of failed attempts, Japanese horticulturist, Dr. Toichi Itoh, successfully created seven peony hybrids from a tree peony bred with an herbaceous peony. These were the first Itoh peonies. Sadly, Dr. Itoh passed away before ever seeing his creations bloom. Years later, American horticulturist, Louis Smirnow bought some of these original Itoh peonies from Dr. Itoh’s widow and continued Itoh’s work.

Growing Hybrid Peonies
Also called intersectional peonies, Itoh peonies share qualities with both parent plants, tree and herbaceous peonies. Like tree peonies, they have large, long lasting blooms and strong stems that do not require staking. They also have dark green, lush, deeply lobed foliage that lasts until autumn. While the foliage grows dense and healthy in full sun, the flowers will last longer if they get some light shade. Itohs are prolific bloomers and get a second set of blooms. They also can grow vigorously to 3 feet (1 m.) tall and 4 feet (1 m.) wide. Itoh peonies are also resistant to peony blight.

Plant Itoh peonies in full sun to part shade and in rich, well-drained soil. Itoh peonies are sensitive to high levels of nitrogen. When fertilizing in spring and summer, be sure to use a fertilizer that contains a low level of nitrogen, like 4-10-12. Do not fertilize peonies in late summer to fall.

Itohs can be deadheaded as needed throughout the spring and summer. In autumn, cut back Itoh peonies to about 4-6 inches (10-15 cm.) up from the soil level. Like herbaceous peonies, Itoh peonies will come back in spring from the ground. In fall, you can also divide Itoh peonies just as you would divide herbaceous peonies.