Pursuit of the perfect peony
By Times Columnist (Victoria)May 23, 2006

An exciting new breed of peony is being made available this spring, thanks to a groundbreaking propagation technique developed by Quebec company Planteck Biotechnologies.

Called "Itoh peonies" after the Japanese nurseryman Toichi Itoh -- who in 1948 was the first to succeed at doing what many thought impossible, crossing yellow tree peonies with the common garden peony, P. lactiflora --the new cultivar offers gardeners the best of both worlds: compact peony plants with attractive, bushy, deciduous foliage and colourful, large, never-before-seen flowers.

While tree peonies have woody stems and stay above the ground like any other shrub in winter, garden peonies are herbaceous and die back to the ground in fall.

Itoh made more than 20,000 crosses before getting the result he was seeking. He finally succeeded in making an intersectional cross between Paeonia x lemoinei, a hybrid tree peony, with P. lactiflora Kakoden, a white-flowered herbaceous peony.

From his original cross, he planted 36 seedlings, which didn't bloom until 1964 -- eight years after his death. Of the 36, six were considered outstanding and were the first peonies of herbaceous character to have deep yellow, double flowers.

Although the hybridizing breakthrough was achieved more than half a century ago, the Itoh peonies never caught on in a big way because of propagation problems. Several attempts were made to propagate them in a large enough number to make them commercially viable, but young plants repeatedly succumbed to fungal pathogens.

In 2004, Planteck hit on a new technique using tissue culture in a laboratory to achieve a high rate of success. Planteck is now the only company in the world that can produce Itoh peonies in mass numbers.

John Schroeder, of Valleybrook Gardens in Abbotsford, one of the biggest perennial growers in Canada, heard about Planteck's success last year and took shipment of some of the new Itoh peony seedlings.

The first batch of five is being made available this month at garden centres in B.C. Their names are Bartzella, Cora Louise, Going Bananas, Julia Rose and Copper Kettle. Colours range from golden yellow to pale pink to coppery orange with touches of red.

They all form dome-shaped plants about 60 to 90 centimetres (two to three feet) with flowers measuring about 20 cm (eight inches) across.

Itoh died in 1956 before he got to see any of the seedlings flower. For more than a decade after his death, his remarkable achievement went unrecognized by the horticultural establishment.

Then in the late 1960s, Louis Smirnow, an American horticulturist, got permission from Itoh's widow to patent four of the new hybrids: Yellow Crown, Yellow Dream, Yellow Emperor and Yellow Heaven. Smirnow's efforts brought Itoh's work to a larger audience.

In the 1970s, the American Peony Society looked at the new hybrids and named them after Itoh. Many breeders still prefer to call them "intersectional hybrids."

Vigorous plants, the Itoh peonies flower in May and June, sometimes producing a second flush if the plant is pruned after the flowering, and have a high resistance to peony blight, a problem in damp climates.

Other hybridizers have picked up where Itoh left off and made some successful crosses.

Don Hollingsworth, of Missouri, produced Garden Treasure, and Roger Anderson, of Fort Atkinson, Wisc., produced Bartzella in 1986. Divisions of this highly desirable cultivar were sold for $1,000 US each.

Anderson is now the best-known breeder of intersectional peonies. He has raised about 400 cultivars, including Cora Louise and Copper Kettle. One of his latest hybrids, Sequestered Sunshine, is selling well as a florist's flower.

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