All About Itoh Peonies

Magnificent Itoh Peonies - A Gardener’s Dream Come True

Itoh peonies, with their spectacular flowers and beautiful colors are a gift to gardeners everywhere.

Itoh peonies originated by crossing herbaceous peonies and tree peonies, and they combine the best features of each. While they have the mounded growth habit of herbaceous peonies and die back to the ground in winter, they also produce immense flowers like tree peonies.

Awesome flowers in a rainbow of colors

Itoh peonies have enormous flowers up to eight inches across, with undulating petals encircling a froth of yellow stamens. All the original Itoh cultivars were yellow, but today they come in a wide range of beautiful colors including coral, red, pink and white, as well as their signature buttery yellow.

A grand finale for the peony season

Just as the herbaceous peonies are winding down, the Itoh hybrid peonies burst into bloom, thus extending the peony season by two more wonderful weeks.

Itoh peonies develop their first flowers from the terminal buds. And then, just as these finish flowering, the side buds begin to bloom.

In this way a single established Itoh peony plant can produce three dozen or more blooms over an extended three week period.

Beautiful plants all the way to fall

Itoh peonies have finely divided leaves which grow close to the ground in an elegant mounded shape. So, long after they have finished flowering, the plants themselves continue to shine at the front of the border.

Where Can You Grow Itoh Peonies?

Like their herbaceous parents, Itoh peonies appear to be extremely cold hardy. However it is important to note, that since they are new for many gardeners, hardiness experiences are still being collected for specific Itoh cultivars.

One such report tells us that the cultivar ‘Garden Treasure’ is flourishing in Edmonton CA, which has a hardiness zone of 3b (winter temperatures may dip as low as -35F) plus other claims of Itoh hybrids surviving even colder temperatures (http://www.theprairiegarden.ca/PDFs/Peonies-in-the-Prairies.pdf).

By contrast, the flower buds on tree peonies will not survive if the winter temperatures dip below -25F.

However, like their tree peony parents, Itoh hybrids are also recommended for warm weather places like southern California. Paradoxically, in these climates, because the winters do not get cold enough, it is the herbaceous peonies that are difficult to grow. (http://sonomamg.ucanr.edu/Plant_of_the_Month/Peonies/)

The Fascinating Story of Itoh Hybrid Peonies

Itoh peonies began as a hybridizer’s fantasy—which was to cross tree peonies with herbaceous peonies and thus to produce a new kind of plant that offers the best features of both parents.

For many years and in several countries, hybridizers had unsuccessfully pursued this goal. One difficulty was because the bloom times for the two types of peony are several weeks apart, making cross-fertilization difficult.

Also, although tree and herbaceous peonies are both members of the huge genus Paeonia, genetically they are actually not that closely related, contributing to the problem of creating a cross that would produce viable progeny.

Because of these genetic differences between tree and herbaceous peonies, modern taxonomists have actually assigned them to different ‘sections’ within the main Paeonia genus. And for this reason, these modern hybrids are sometimes called ‘Intersectional’ peonies.

A dream came true

Dr. Toichi Itoh, a Japanese botanist, toiling in the aftermath of the horrors of World War II, was the first person to successfully combine the pollen from a tree peony with the ovary of an herbaceous peony.

He was totally consumed with this monumental hybridization challenge and made thousands of attempts. Finally in 1948 his dream came true—a few of his seeds germinated. But it would take over a decade of patient oversight before those seedlings grew to full size and produced flowers. Then in 1956, eight years after his successful crosses, sadly Dr. Itoh passed away.

So it fell to his family to nurture those special plants, finally bringing them to flower in 1964. Eventually an American botanist, Louis Smirnow, got permission from Dr. Itoh’s widow to bring some plants to the USA where he patented four hybrid peonies—which he named Itoh hybrids— featuring huge buttery yellow flowers.

'Cora Louise' Itoh Peony — 'Cora Louise' is a striking Itoh Peony, with semi-double white blooms that feature a dramatic burst of cranberry-pink at center and surround vibrant, golden frills. <a href="/perennials/peony">Shop Our Peony Collection</a>

American breeders get involved

Peony breeders everywhere were motivated to try to replicate Dr Itoh’s detailed techniques and produce new hybrids in both yellow and other colors.

Bartzella: brilliant yellow petals with red at the center

Canary Brilliants: flowers are pinkish when they first open but turn yellow as they mature

Cora Louise: the creamy white petals have red at the center

First Arrival: bright pink

Garden Treasure: yellow petals with red at the center

Scarlet Heaven: single scarlet petals contrast with yellow stamens

Julia Rose: soft apricot petals with reddish tips

The rootstock of the Itoh peonies we sell at American Meadows are all created from root divisions of mature plants, rather than by tissue culture in the laboratory, thus assuring they will be sturdy and true to name.

Gold medal winners

In 1996 the American peony Society gave their coveted Gold Medal Award to Itoh hybrid ‘Garden Treasure’ and in 2006 to ‘Bartzella’ in 2006, both of which we sell at American Meadows.

Bartzella Itoh Peony - American Meadows — 'Bartzella' Itoh Peony, with charming yellow blooms streaked crimson red at center. Each unusual bloom carries a sweet, citrusy fragrance and measures up to 8 inches across. <a href="/perennials/peony">Shop Our Peony Collection</a>

A personal story from Judith Irving

In the summer of 2000, when Itoh hybrids were barely known in the gardening world, I was visiting the renowned peony grower, Bill Countryman in Northfield, Vermont. Over the years he had developed a fabulous collection of peonies, including every American Peony Society's Gold Medal winner to date. And now he was adding Itoh hybrids to his collection.

As he showed me his plants he also recounted me the incredible story of how they came to be.

I was smitten and purchased a single root stock of Garden Treasure, at a hefty price of $125.00. But my husband was absolutely horrified that I would even consider spending that much money on a single root!!

I chose a sunny spot and enriched the soil with plenty of compost and within a couple of years my new plant was flourishing in our Vermont mountain garden. And now every June, just as the flowers of the herbaceous peonies fade, my husband and I together eagerly await the moment when our Garden Treasure starts to bloom. It is by far the most beautiful plant in our garden, and it has more than lived up to the promises Bill made to me those many years ago.

About the Author: Judith Irven is an accomplished Vermont landscape designer and garden writer, and she delights in helping people everywhere create beautiful gardens. You can visit her online at: OutdoorSpacesVermont.com.

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