William L. Ackerman

A TRULY COLD-HARDY camellia has long been a dream of northern gardeners.  Even in the milder areas of the mid-Atlantic region, where camellias have been grown for many years, cold hardiness has become a concern.  At the U.S. National Arboretum, in Washington, D.C. (USDA Zone 7a), where I conducted my research on camellias, we would occasionally get a hard winter freeze that did some plant damage, but rarely would any of the spring-blooming Camellia japonica or fall-blooming C.sasanqua cultivars be killed.  Farther south, damage to the plants themselves was almost unknown, although there might be cases of flower bud injury.

The whole concept of cold hardiness changed for us following the winters of 1977 - 78 and 1978 - 79, when temperatures fell as low as -2 degrees Fahrenheit, accompanied by strong, drying winds.  Among the arboretum's nationally recognized collection of more than 900 specimens, most C.sasanqua cultivars were killed outright that first winter, and the C.japonica cultivars were badly injured.  Even C.japonica cultivars considered to be the most hardy, such as 'Bernice Boddy', 'Governor Mouton', 'Kumasaka', 'Lady Clare', and 'Pink Perfection', were devastated.  By 1980, the arboretum's once outstanding collection had been reduced to a half-dozen struggling plants and sprouting stumps.  There was, however, a notable exception: a specimen of the fall-blooming C.oleifera, a white-flowered species introduced in 1948 from northern China.  It came through both of those brutal winters unscathed and has done so every winter since, blooming normally despite severe temperatures.

Camellia oleifera is widely grown in the Orient, not as an ornamental, but as a source of seeds, which are pressed to produce cooking oils. (Indeed, the Latin epithet oleifera means "oil bearing".)  The oil is also used as a hair dressing and in cosmetics. The plant's virtues as a cold-hardy parent, however, were not immediately obvious.  For although this camellia makes a handsome evergreen shrub with an upright habit and glossy dark green foliage, its single flowers shatter badly when cut and even when left on the plant.

Nevertheless, given the proven hardiness of the arboretum specimen, it seemed only natural to test other sources of this species.  We secured five strains of C.oleifera that had been collected throughout the Orient.  Of these, only one was comparable in hardiness to our plant.  Indeed, one strain from Taiwan was even more tender than many varieties of C.sasanqua.

Once we had established that the arboretum's plant would make the best parent, the breeding program began in earnest.  Between 1979 and 1981, 2,500 interspecific hybrids were made between the arboretum's C.oleifera and various C.sasanqua and C.x hiemalis cultivars.  In addition, a series of C.oleifera hybrids I made in 1969 during a species compatibility study were back-crossed to C.oleifera.  The entire group was greenhouse grown until 1982 and then planted out for field testing at 14 locations in Pennsylvania, Maryland, Virginia, North Carolina, and the District of Columbia.  Protection from the elements varied at the individual sites, ranging from an overstory of mature pines or deciduous trees to lath and shade houses.

We made a second series of crosses between 1980 and 1984, which resulted in more C.oleifera hybrids.  This time, however, spring flowering parents including C.japonica and C.x williamsii were used.  Field evaluation and selection among these hybrids is still being carried out, so several years will be needed before any of these are named and introduced.

Since 1982, the breeding program has concentrated on evaluating individual plants at the various locations for their cold hardiness.  Thus far, they have experienced minimum temperatures ranging from -4 degrees to -15 degrees F.  Perhaps the most severe test occurred during the third week of January 1985, when temperatures, which had been very moderate (40 to 50 degrees F), suddenly plunged to between -10 and -17 degrees F. Plants that showed little or no injury were then judged for their flower quality and overall marketability.

We have concluded that the fall-blooming hybrid camellias are most valuable as landscape plants, attractive as their flowers are.  In the landscape, they are far more appealing than most cultivars of C.japonica: Their leaves are smaller and, in most cases, a shiny dark green.  Most will also flower at an early age -- some the second year from rooted cuttings.  And although they are not meant to produce show flowers, they will not all shatter after being cut, unlike most C.sasanqua cultivars.  In fact, the cut flowers of certain hybrids can last as long as four days.

Because the last three years have been relatively mild, these hybrids began to flower in my Maryland garden in early October, and the plants had at least some blossoms out every week through the first week in January.
During November and December we have had some hard freezes that browned all the open flowers, yet, following a change to more moderate temperatures, many of the more immature buds came into bloom.

My guess is that most of the breeding and development work for cold-hardy, fall-flowering hybrids has been completed.  There is now a substantial group of these plants that is capable of withstanding comparatively severe winters, and of bearing flowers of equal or better quality than those of existing C.sasanqua cultivars.  In selecting hybrids worthy of commercial distribution, we have made an effort to provide a diversity of flower and plant forms.  The flower shapes include single, semidouble, formal double, peony, anemone, and rose forms, in colors ranging from white through various shades of pink to lavender. (As yet, there are no true reds.)  The plants themselves may be compact and upright, spreading, or pendulous; 12-year-old specimens are typically five to eight feet in height, depending on the cultivar.

These cultivars are now being successfully established in areas where camellias were not previously grown outdoors.  New England has never been considered "camellia country," yet these plants are thriving in coastal regions of Connecticut, Rhode Island, and Massachusetts.  A hardy camellia is no longer a dream.  Gardeners who live in areas where the winter extremes do not fall below -10 degrees F (Zone 6a), and where some protection from winter wind and early morning sun can be provided, should be encouraged to try these durable and exciting hybrids.

The following nine fall-flowering selections have been named and are available from retail nurseries:

'Polar Ice'
White, medium-size flowers, anemone form, very late blooming; spreading habit

'Snow Flurry'
White, medium-size flowers, anemone to peony form, very early blooming, smaller flowers than 'Polar Ice', very floriferous; spreading habit

'Winter's Charm'
Lavender-pink, medium-size flowers, full peony form, early blooming; upright habit

'Winter's Dream'
Pink, medium-size flowers, semidouble, midseason; compact, upright habit

'Winter's Hope'
White, medium-size flowers, semidouble, late blooming; spreading habit

'Winter's Interlude'
Lavender-pink, medium-size flowers, anemone form, midseason; upright habit

'Winter's Rose'
Shell-pink, miniature flowers, rose-form double, very floriferous, very early blooming; small leaves, slow, compact, spreading habit

'Winter's Star'
Reddish pink, some with white centers, medium-size flowers, single, midseason; compact, upright habit

'Winter's Waterlily'
White, medium-size flowers, formal double, slightly incurving petals, late blooming; upright habit