New Rhododendrons and Azaleas for 1964
David G. Leach
Note - This article appeared originally in the American Nurseryman, April l0, 1964, p. 7. The information contained therein appeared to be of such interest to our members, particularly to those in the East, that both author and publisher were contacted concerning the possibility of reprinting it in the A.R.S. Bulletin. Both very kindly gave their permission, for which we are grateful.
After a century during which a single release of a new rhododendron hybrid for the northeastern United States was a rare and important event in the nursery industry, the 1960's have already seen a score of novelties introduced. Another contingent is making its bow in 1964. Before this decade is over, it may become the main period for origination of garden rhododendrons for the next century, comparable to the 1860's and '70's, when Anthony Waterer, at the famous old Knap Hill Nursery in England, produced the hybrids that have been the mainstay of the American nurseryman in the northeast since that time.
American breeders were notably unsuccessful in competition with British and Dutch hybridists until recent years. Now the focus of interest has swung westward, and our own rhododendron introducers are making the horticultural contributions of value to professional growers, just as the American originators replaced the Oriental sources of evergreen azaleas about 25 years ago.
The 1964 release that will probably arouse the widest interest is not a rhododendron, but an evergreen azalea, 'Hino-Red', a patented clone from A. M. Shammarello, South Euclid, O. The flowers are about an inch and a half across, a good deal larger than its Hino-type predecessors, and of a radiating color quality which seems to shimmer in the sun. Unlike so many reds, it is non-fading. It blooms about May 10, and many of those who have seen it in flower believe it is one of the most promising persistent-leaved azalea introductions.
Frost Date Important
The introducer finds 'Hino-Red' bud hardy to -19 degrees Fahrenheit, and from its published parentage it could be assumed to be a good deal hardier than the popular reds now in commerce. But low winter temperature is not the most important factor in satisfactory performance of evergreen azaleas. The average date of the first fall frost is much more influential in determining whether the buds will remain uninjured to flower the following spring.
'Hino-Red' originates in United States Department of Agriculture plant hardiness zone 6b. It should be a safe prediction that it will be completely satisfactory for climates in which the first fall frosts come at the end of October. Time and further testing will tell how much earlier the frosts may occur in severer climates without injury to the buds, but 'Hino-Red' seems certain to become a standard azalea in the nursery lists. It has all of the quality marks of a successful clone, plus the radiant red flowers so attractive to homeowners. It is an ideal foundation shrub for single - story houses, with a height of only 18 inches and a spread of three feet in 10 years. The Warren Baldsiefen Nursery, Rochelle Park, N.J., is introducing 'Warwick' this spring, another in the recent procession of Dexter hybrid rhododendron releases, but one which appears to be much hardier than its predecessors. 'Warwick' is a pale mauve pink, the 3-inch flowers individually large and collectively imposing in the full, firm truss. For such a rugged rhododendron it is remarkable also in being fragrant. Inasmuch as it bloomed fully in northeastern New Jersey in 1963, following the coldest winter in 80 years, the introducer recommends it for zone 5, with climates equivalent to those of Worcester, Mass.; Albany, N. Y.; Scranton, Pa., and Youngstown, O., where it has been found bud hardy in a range of -10 to -20 degrees F. This is a vigorous rhododendron of conventional stature.
By way of preview, this same nursery will release in the fall of 1964 the long-awaited 'Dora Amateis', an extraordinary dwarf white-flowered rhododendron, which resulted from a cross between the hardy native R. carolinianum and an Asian species, R. ciliatum, of great ornamental value. This remarkable mating succeeded for the breeder, Edmond Amateis, after other hybridists had failed in similar efforts for many years. 'Dora Amateis' comes close to being the ideal white-flowered dwarf shrub, its polished evergreen leaves of finer texture than conventional hybrids making a dense mound of attractive foliage the year round.
Other Dexter Varieties
The James S. Wells Nursery, Red Bank, N. J., is introducing this spring three new rhododendrons from the Dexter breeding; 'John Wister', 'Merley Cream' and 'Wissahickon'. 'John Wister', named for the beloved dean of American horticulture at Swarthmore College, has large light pink flowers, frilled, fragrant and freely produced. It is a vigorous grower, somewhat globe-shaped in outline, with shiny dark green foliage, and it blooms about May 20. A few plants may be around under the designation, Dexter No. 201.
'Merley Cream' will probably be more a connoisseur's clone than a standard commercial cultivar. It has the scented ivory flower with a yellow center, quite large in size, sought by hobbyists and sophisticated gardeners, but professional growers will not find it an easy plant to produce and grow on to creditable stock of budded landscape size. Like almost all rhododendrons of this subtle color, the foliage tends to be light green. Habit is upright. The flowering period is an added attraction, coming as it does the second week in May, almost three weeks before the big show of midseason rhododendron bloom.
'Wissahickon' has been admired at the Morris Arboretum, Philadelphia, Pa., by nurserymen under the label Morris No. 3 for its very early bloom, May 1, from medium-size flowers of bright rose color. It is not so hardy as the other Dexter introductions from Mr. Wells, and the growth habit is somewhat open. It may be a good forcing rhododendron.
Variation in Hardiness
The Dexter hybrids vary enormously in hardiness, to such an extent that their climatic adaptability ranges from zone 5a to 8a on the U. S. D. A. plant hardiness zone map. Some lose their buds at-20 degrees F., others at +10 degrees F. Nurserymen invariably inquire first about the hardiness of rhododendron introductions, and there is no good answer until the newcomers have been grown in a range of climates which tests their limit of satisfactory performance. The professional grower who wants to expand his list from the overly familiar century-old Catawba hybrids must make a cautious gamble if his climate is severer than that of the originator. Sandwich, Mass., on Cape Cod, where C. O. Dexter carried on his hybridizing, is in zone 7a, as is also the New Jersey nursery of the introducer. Zone 7a has an average minimum winter temperature of 0 degrees F.
An interesting development in rhododendrons of the past several years has been the reappearance in this country of several of the good old British hybrids, which dropped out of the lists in the 1920's. These are all characterized by dense growth habit and a mature height of about five feet; so the reason is obvious for their revival in landscaping small gardens and single-story homes.
Of this group, 'Chionoides', offered by both Koster Nursery, Bridgeton, N. J., and James Wells, is probably the most outstanding. The flowers are a delicate ivory white, cup-shaped, small in size and combined into neat conical trusses atop handsome, dark green, pointed leaves densely clothing the plant, so that it is also an evergreen asset in the garden the year around. This hybrid has style, the indefinable air of quality and distinction which sets it apart from its competitors, and it proves that it does not take large flowers to give a rhododendron unusual appeal. Although it was introduced by John Waterer, Jr., in 1880, it has never lost its popularity in the colder parts of England. Floriferous and reliable, it blooms 10 days before the familiar midseason Catawba hybrid clones.
Demand for White Hybrids Another interesting development in the nursery industry during the past several years has been the sudden consumer demand for white-flowered clones. Only four or five years ago many a nurseryman surveyed his field rows at the end of the season and noted with concern the white hybrids remaining unsold. Today the same grower is more likely to be out cruising the wholesalers trying to pick up enough white to fill the 1964 demand. 'Mont Blanc', an old hybrid introduced by the Scottish nursery firm of Methven, in 1868, has been revived by the Wells Nursery to fill the need for early-blooming dwarf whites. It flowers the first part of May, and the blooms have a reddish blotch that warms the color pleasingly.
'Euclid' and 'James MacIntosh', of the same era of British breeding, are two rosy-red clones of dwarf stature and compact growth habit that complete the reintroduction by Mr. Wells, the one succeeding the other in bloom before the familiar midseason hybrids come into flower.
This group of "revived" rhododendrons is in the general category that was formerly rated "A" for hardiness by the Royal Horticultural Society, but this covered a range much too wide for American conditions. I have grown two of these clones and I feel that they would not be satisfactory ornamentals in zones 5a and 5b. They seem good bets for zone 6b and warmer, that is, south of a line drawn from about Harrisburg, Pa., to Providence, R. I.
The new rhododendron introductions of the past several years have received so much publicity in the popular gardening magazines that the decline of the century-old standbys seems inevitable as the buying trends filter down from the gardening hobbyists to the more casual purchasers. An aversion to the ubiquitous lavenders and bluish pinks is already evident in the sales lots. It appears likely to be a question of which hybrids to replace and which to add, for the nurseryman who wants to stay with rhododendrons in good volume.
The Shammarello Nursery has a new group of releases for 1964. Of Mr. Shammarello's 1962 introductions, 'King Tut' and 'Pinnacle' proved to have wide adaptability, well into zone 5, and the others are finding their regional limits of usefulness as they are grown and tested in a variety of climates.
Among the 1964 introductions, 'Bessie Howells' is the hardiest and will probably take its place for cold resistance with 'King Tut' and 'Pinnacle'. It is both dwarf and compact and flowers about 10 days before the too familiar sorts of present commerce. It buds as heavily as any rhododendron that has ever been introduced and produces a showy display unfailingly year after year. The flowers are frilled, of distinctive appearance, with a dark red blotch on a vinous-red ground.
Nurserymen either admire the bluish-red color with a mat finish or dislike it intensely, but the public seems to cast a vote preponderantly favorable. Whatever the professionals' private opinion, this rhododendron will probably sell well, and it is one of those easy, carefree growers and willing propagators that present no problems.
'Juliet', delicate light pink, and 'Romeo', an unusual blood-red hybrid, are both unlike anything now in the lists for both flower color and quality. They will more than hold their own with the present midseason competition, so different that they are more likely to be additions than replacements. They have been widely admired by specialists in the Shammarello test garden.
'Spring Parade', red, has a compact habit so superior to the usual run of this gaudy tribe that, combined with its early blooming season, it will deserve a trial in climates where R. caucasicum hybrids do not tend to bloom partially in the fall.
'Sham's Ruby', 'Sham's Pink', a vivid color with a darker edge, and 'Pink Flair', light pink with a bold red blotch, the latter two flowering 10 days before midseason, complete the Shammarello introduction for 1964.
Further Testing Required
The nursery of the originator is in U. S. D. A. hardiness zone 6b, equivalent to the climate of Pittsburgh, Pa.; Trenton, N. J.; Waterbury, Conn., and Providence, R.I. In any normal season the Shammarello hybrids should be satisfactory under such conditions. Time and further testing will determine which can be recommended for severe climates.
The novelties in deciduous azaleas for 1964 again come from the Bovees, Portland, Ore. It was inevitable that American breeders would take the fine British Exbury and Knapp Hill hybrids and from them produce descendants even better adapted to American growing conditions. Those who have followed the continuing displacement of the old, short-lived Mollis hybrids by the greatly improved English imports have more recently been aware of the success of the Bovee hybrids from Portland. 'Cathe Mayo', with old-gold flowers an incredible five inches in diameter, and 'Sandra Marie', an opulent yellow and pink blend in 4½ inch blooms, were the first deciduous azaleas ever to win the P.A. award of the American Rhododendron Society. 'Goldflake', possibly the most vivid yellow yet produced, and 'Sweet Sue', a big, bright pink, followed the initial releases and were also instantly accepted by many specialists as the best of all the new giant-flowered hybrids, British or American, in their color classes.
Now the Bovees are making three 1964 introductions under number: BK 12, a brilliant orange yellow; BK 37, with heavily ruffled white flowers and colorful autumn foliage; and BK 55, which has bright burnt-orange flowers fluted and waved around the edges.
The Bovee deciduous azalea hybrids appear to be just as hardy as the British hybrids and somewhat more suited to the warm May days of the American spring in their flower substance. They are satisfactory well into zone 5, where the average minimum winter temperature ranges from -10 degrees to -20 degrees Fahrenheit.