Breeders have overcome genetic barriers to create these tough, gorgeous hybrids
by JAMES W. WADDICK
photography by DONNA KRISCHAN
IT SEEMS THAT EVERY GROUP OF PLANT HYBRIDIZERS has its own impossible dream: for rosarians it’s a blue rose; for bearded iris fanatics, a truly red iris. For peony fanciers—at least for many decades—it was a deep yellow, large-flowered, easy-to-grow herbaceous peony. This seemingly unreachable goal, however, has been achieved; in fact, the earliest examples of these “improbable peonies”—which now come in a wide spectrum of sumptuous colors—are nearly 50 years old. Strangely, most gardeners are unaware of these desirable hybrids, even though they are available from specialty nurseries and are held in special esteem by devoted peony growers. Like all stories that involve beating the odds, theirs is a compelling one.
THE CHALLENGE The first barrier to breeding a good yellow herbaceous peony was the dearth of genetic material among the possible candidates for parents. Paeonia mlokosewitschii, from the Caucasus Mountains of eastern Europe—the first yellow-flowered herbaceous species to be discovered—looked promising at first. Named in 1900, it was quickly brought into cultivation. Although fairly easy to grow and an attractive light yellow in its best forms, the flowers are single and short-lived. Furthermore, it proved disappointing as a parent, repeatedly failing to produce any good, bright yellow offspring.
Another candidate turned up during the Japanese occupation of northeastern China in the 1930s. Discovered blooming on the grounds of the last emperor’s palace in Changchun, in the heart of Manchuria, it was a double-flowered yellow that went under the Chinese name ‘Huang Jin Lin” (translated as “golden wheel”). It was brought to Japan (where it became known as ‘Yokihi’) and introduced into cultivation. A series of circuitous and mysterious moves finally brought it to the United States in 1954, where it was registered as ‘Oriental Gold’. For all the romance of its origin, it proved difficult to grow, harder to flower, and expensive to boot. Moreover, its few hybrids were similarly disappointing.
AN ELUSIVE GOAL In contrast to the dearth of yellow herbaceous peonies, there were plenty of good yellows among tree peonies, thanks mainly to two species from western China: Paeonia lutea, discovered in 1884, and P. delavayi, discovered in 1921. Brought to Western Europe, these species grew well, bloomed, and created a sensation. Between the 1890s and 1930s, the French hybridizer Victor Lemoine used P. lutea (along with P. suffruticosa and Japanese hybrids) to produce the first of the large, double-flowered “lutea hybrids,” some of which, such as ‘Alice Harding’, ‘Chromatella’, and ‘Souvenir de Maxime Cornu’, are still in cultivation. These were probably the inspiration for a host of yellow-flowered tree peonies produced in the 1940s by the talented American hybridizer, A. P. Saunders.
1. ‘Watermelon Wine’
2. ‘First Arrival’
4. ‘Scarlet Heaven’
Pick of the Best Intersectionals
|‘Bartzella’||Anderson||semidouble, bright yellow, upright; a gem|
|‘Cora Louise’||Anderson||semidouble white with a darker red center|
|‘Garden Treasure’||Hollingsworth||semidouble yellow, spreading habit; award winner|
|‘Julia Rose’||Anderson||single to semidouble flowers of red, orange, and yellow on one plant|
|‘Morning Lilac’||Anderson||single deep red flowers on a rounded bush|
|‘Viking Full Moon’||Pehrson/Seidl||soft yellow rounded flowers on a 3-foot plant|
|‘Yellow Crown’||Itoh||dwarf plant (to 20 inches) with yellow flowers with red central flares|
|‘Yellow Dream||Itoh||see under ‘Yellow Crown’|
|‘Yellow Emperior’||Itoh||see under ‘Yellow Crown’|
|‘Yellow Heaven’||Itoh||see under ‘Yellow Crown’|
5. ‘Julia Rose’
6. A new unnamed Roger Anderson hybrid
7. ‘Pastel Splendor’
8. ‘Cora Louise’
Now, if the superior floral qualities of the yellow-flowered tree peonies could be transferred to herbaceous peonies, the problem would be solved. But according to conventional wisdom, the genetic barriers between tree peonies and herbaceous peonies ruled out any attempts to cross the two groups. (See “The Different Kinds of Peonies,” page 48.) Conventional wisdom, however, turned out to be wrong.
SUCCESS In Japan, around 1948, an avid amateur gardener named Toichi Itoh applied the pollen of the yellow tree peony ‘Alice Harding” to the Japanese herbaceous peony ‘Kakoden” and obtained viable seeds. Most of the resulting seedlings looked like herbaceous peonies, but nine had foliage more typical of tree peonies. Eventually, all but six of these died; sadly, Itoh himself also died in 1956, without ever seeing his “impossible” hybrids flower. Fortunately, Itoh’s assistant kept the remaining six seedlings growing until they eventually flowered for the first time in 1963. All of them were short in stature, to about 20 inches, and had large, deep-yellow, semidouble flowers; four of the best were registered in 1974 as ‘Yellow Crown’, ‘Yellow Dream’, ‘Yellow Emperor’, and ‘Yellow Heaven’. (Some experts believe that these four have now become hopelessly mixed up in the trade.) The vigorous plants had the attractive foliage of their tree peony parent while retaining the herbaceous nature and increased hardiness of their herbaceous parent. Their appearance set off a storm of further hybridizing attempts.
A minor furor arose over what to call the new peonies; on the one hand, there was a substantial body of opinion in favor of calling them “Itoh hybrids,” in honor of their originator, but there were also many sensible arguments in support of the name “intersectional hybrids,” because eventually a number of other species and hybrids unknown to Itoh were used in breeding these peonies. On balance, intersectional hybrids seems to be the most appropriate label.
IMPROVING ON ITOH Repeating Itoh’s success proved challenging. It was soon determined that not just any cross would work, and even then only a very few attempts resulted in fertile seeds. By the mid-1980s, however, several American breeders had managed to release new intersectionals. The first was nurseryman Don Hollingsworth, proprietor of Hollingsworth Peonies in Maryville, Missouri, whose hybrids ‘Border Charm’, ‘Prairie Charm’, and ‘Garden Treasure” varied in the strength of their yellow coloration. ‘Garden Treasure’, however, a cross between the tree peony ‘Alice Harding” and an unnamed herbaceous seedling, really threw down the gauntlet to other breeders. This plant was larger than the original Itohs, and had a better growth habit. The flowers can reach a full eight inches in diameter, and are a bright, clear yellow with small red “flares” at the center. ‘Garden Treasure” went on to receive the Gold Medal of the American Peony Society, and demand still far exceeds the supply.
More recently, the hybridizer Roger Anderson, owner of Callie’s Beaux Jardins in Fort Atkinson, Wisconsin, has introduced more than 20 new intersectionals that have dramatically expanded the group’s color range to include pink, white, lilac, orange, copper, and bicolors. Outstanding among his yellows is ‘Bartzella’, an improvement in many ways on all other yellow-flowered peonies. It is an upright grower, reaching nearly 36 inches in height. The large (up to eight inches) flowers are a clean, bright yellow with small, central reddish flares, and practically cover the plant. ‘Bartzella” is also fast growing and quickly reaches specimen size. Some fanciers consider it the world’s most desirable peony.
9. ‘Bartzella’, showing foliage and plant habit
Although achieving a good yellow was the original impetus behind the creation of the intersectionals, it is hard to resist some of Anderson’s more novel colors. ‘Kopper Kettle’, for example, is a mix of red, yellow, and orange, giving an overall orange/copper impression. ‘Pastel Splendor” (introduced with W. Seidl) is mostly white but suffused with light pink and yellow, blending into a rich red center. ‘Cora Louise” takes this a step further with near-white petals with contrasting lavender-purple central flares. ‘First Arrival’, the earliest of Anderson’s intersectionals to bloom, is a full-flowered lavender pink on a perfectly formed bush. The unusual ‘Julia Rose” opens cherry red, then fades to orange and near yellow. All three colors can be seen on one plant. Anderson’s reds range from the pale ‘Watermelon Wine” to the deep ‘Scarlet Heaven” and the aptly named ‘Unique’, which inherited its finely cut foliage from the red-flowered woody species P. delavayi.
Although it’s the flowers of Anderson’s hybrids that grab your attention, he is justifiably proud of their attractive, long-lasting foliage, which looks almost as fresh in September as it does in May.
BEAUTY-AT A PRICE Surely, you must be thinking, there’s got to be a catch with these dazzling plants; otherwise they’d be flooding my local garden center. There is: they’re expensive. ‘Bartzella” sells for $250, while the award-winning ‘Garden Treasure” is a relative bargain at $125. Most other intersectionals sell from $100 to $200 each. Why the astronomic prices? First of all, the crosses are difficult to make, demanding extreme patience. Seedlings take years to a decade to mature and produce their first bloom. Finally, propagating them is dauntingly slow. Intersectionals produce huge root systems, and their woody peony parentage means that they have tough stem bases and crowns; division, therefore, is laborious and produces relatively few new plants. (Tissue culture, unfortunately, doesn’t work with peonies.)
But once you’ve gotten over your sticker shock, you can’t help but appreciate their sterling qualities. They are relatively trouble free, fast growing, and extremely hardy—to USDA Zone 3 or even 2. Most have an extended bloom season, and in mid-north latitudes can last well into June. And any intersectional will be delightfully different from all the other peonies in your garden.
So what is in the future of these fantastic plants? It’s likely that their color range will continue to expand, to pure white and exotic blends and bicolors. Also expect to see distinctive foliage, the possibility of repeat bloom in the fall, and fully fertile plants that will make breeding them less of a challenge. But more important, as they become better known and more intensively propagated, their price will surely fall, making these peonies of the future increasingly available to gardeners across the country.
For sources of plants featured in this article, turn to page 88.
THE DIFFERENT KINDS OF PEONIES
PEONIES FALL INTO THREE GROUPS, or subgenera: the tree or woody peonies; the majority of herbaceous peonies; and the one or two American herbaceous peony species, which are of interest primarily to specialists. Tree peonies have been grown for centuries in Chinese and Japanese gardens. Although called “tree” peonies, none actually attain treelike proportions; woody peonies is a better term. Most cultivars stay under six feet, but a few (such as ‘Ludlowii’) can grow to nearly double that size. All have woody stems that continue to grow over many years, and should be treated in the garden like other deciduous shrubs of similar size. Most are hardy to USDA Zone 4.
Herbaceous peonies have been grown in the West since ancient times both for medicinal and ornamental purposes. Hardier in general than woody peonies (to Zone 3), herbaceous peonies can grow to up to four feet or so in height, but die down in the fall to below ground level, where their dormant buds wait out winter’s chill. They form the backbone of many gardens, ranking with other perennial favorites such as irises and daylilies. Yellow-flowered varieties are rare, and none are both a good yellow and easy to grow.–J.W.W.
Planting and Caring for Intersectional Peonies
Order plants from a reliable specialty grower for fall delivery. Prepare a planting hole 30 inches across and at least 20 inches deep in a prominent garden location that gets full sun and has well-drained soil. Add ample compost or leaf mold to the excavated soil, along with a handful of ground limestone and balanced fertilizer, and mix well. When your plant arrives, try to determine the former planting depth by locating the dormant buds. These buds should be no more than one or two inches below the soil surface. Fill in the hole, firm the soil, and water well. Spread a thin layer of bark mulch over the crown for protection; this is especially important the first winter. Water and fertilize the plant well during its first year; you can expect bloom in one or two years, maturity in three or four, and glory thereafter. After the onset of cold weather, the stems should be cut to near the ground and discarded (not composted) to prevent the spread of disease. These suggestions also apply to most herbaceous peonies.–J.W.W.