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Journal American Rhododendron Society

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Dr. Glen Jamieson ars.editor@gmail.com


Volume 29, Number 4
October 1975

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Azaleas in Honor Heights Park
Arthur C. Johnson, Muskogee, Oklahoma
Director, Park Recreation Department, Muskogee, Oklahoma

        "You can't grow azaleas in Oklahoma." "It is too dry." "The weather is too unpredictable." "It is too cold and windy." "Remember Oklahoma is one of the dust bowl states." Such were the expressions we were greeted with when we first started talking about growing azaleas in our park system some 20 years ago
        We wanted a spring blooming flower, very colorful, one that would give us mass color effect-not a spot of color here and there, but a bed of good strong color 50' to 100' long, blending well with the natural hillside of our park. None of the usual spring flowering shrubs seemed to provide what we wanted, but we were willing to try something that hadn't been tried. A number of people grew a few azaleas in their dooryards, but their plants were generally greenhouse pot plants removed from the house in the spring. Since a few varieties were being successfully grown on a small scale, maybe, we thought, by studying their needs and trying to fill them, we might be successful - not every time, but enough to make it worthwhile. It was worth a try.

Drainage & Soil
        We felt that drainage and planting soil were the first problems to be conquered. In heavy, tight prairie soil how best could one obtain sharp drainage? The answer was to make all planting beds raised above the surrounding area 10 to 12". These raised beds were filled with a loose humus mixture as close to peat moss as financially possible. We settled on a bed of rotted pecan shells, some sand and just enough peat moss to give the plants an easy out into the mixture. The pecan shells are readily available from local shelling plants. Sometimes salt is used to soften the hard shell, so to avoid any salt damage, shells are stock-piled for from three to five years. This time lapse has the added advantage of helping decompose the shells. These shells also help provide the necessary acidity for successful growth. The beds are surrounded with large loosely laid rocks, blending the beds into the natural hillside and holding the soil mixture in the beds.
Moisture
        The next most important factor was moisture, enough to provide a cool moist soil to raise the humidity and lower the temperature. Azaleas have a shallow root system and are very sensitive to drought so provisions had to be made for summer watering. We solved the problem by putting spray heads on 10 foot-15 foot poles, giving us a gentle rain-like watering.
        This provided a moist atmosphere, lowered the temperature and gave the plants the necessary soil moisture. The raised bed prevented the roots from standing in water, sure death. The watering was often done all night and repeated whenever the soil, one inch from the top level, felt either hot or dry.
Exposure
        Much has been written about the necessity for planting azaleas on the north or east side of a building or planting them where they have high shade, never planting them on the south or west side of a building or in the full sun. We found that this is over rated. Our experience was that, provided you give the plants proper soil and moisture, they will grow anywhere. Those in the sun have better color, but fade much more quickly than those in the shade of trees or building. The plants grow equally well, sun or shade.
Planting
        The best time to plant azaleas is from early spring through the blooming period and up to the middle of June. After the fall rains start, azaleas can again be planted until freezing weather. Planting during blooming period certainly enables one to blend color better and to select the color desired.
        When the soil is properly prepared, a hole just slightly larger than the plant ball should be dug into the planting medium, the hole lined with peat moss and the. azalea placed. Additional peat moss is used to pack around the plant. Azaleas should never be planted any deeper than they were in the nursery if balled, if container grown, should be about 1 inch deeper than the soil in the container. The newly planted azalea should be well watered and watered again each day until the plant seems well settled. Distance between plants will depend somewhat upon the size of the plant, the effect desired and the type of azalea. From three feet to six feet apart might be a good rule.
Fertilizers
        We have never found it necessary to add fertilizer to our planting medium. We have added iron chelate when yellowing of leaves from chlorosis made it necessary. Were fertilizers considered necessary because of either poor growth, or lack of good green foliage color, a standard prepared azalea fertilizer might be used. Let me caution that I strongly feel more azaleas are killed from over fertilizing or too late fertilizing, than from almost any other factor, if all other things are satisfactory.
Acidity
        The problem of obtaining a soil with a pH of 4.5 to 5.5 seems to be solved with the well rotted pecan shells, sand and peat moss mixture.
Hardiness 
        During the twenty-odd years that we have been growing azaleas in our park, nature has been almost always kind. There have been several times when late frosts have browned early blooms or buds, but did no plant damage, even to the more tender Southern Indicas. I recall one year when the 'Formosa' was partly buried under 12 inches of snow. The only part of the plant to bloom was that covered with the snow, but the plant was not damaged and today stands 8 feet high and as wide.
        The winter of 1973-74 was a different story. We had an extremely mild season with many January and February days 69° F and above. By the middle of March, buds on early azaleas were showing color. Although no early growth was evident on the bulk of azaleas, we felt that the sap was ready to flow. Then bang! On March 17th, 18th, and 19th the temperature dropped to 17° F with even daytime temperature remaining below 30° F. This dramatic change resulted in early bud and bloom damage, but even more serious was the bark damage done at the ground level, in many cases completely girdling the stem. We were prepared for a sad azalea season and sent out word that our loss was great - possibly almost half of our plantings. Suggestions from our Mobile, Alabama, friends were no fertilization, cover the damaged bark with moist mulch and water freely. All of this we did as much as possible. The surprising thing was that the plants, where the buds were not damaged, bloomed as usual and then after blooming, many died. The resultant loss was approximately 4,000 plants.
        We would like to be able to list those varieties that didn't survive, but we can find no pattern to work from. Neighboring plants in large beds of the same variety responded differently: One died, one looked sick with perhaps one branch left living, and one bloomed and grew as though nothing had happened.
        Of all the types of azaleas, Glenn Dale appeared to suffer the least. Next was the Kurume, on down to Back Acres and Satsuki. The last two appeared to suffer the most, not with loss of plant, but with many stems killed to the ground. Fortunately, in many cases new growth appeared below the freeze damage so the plant will eventually replace itself. It was interesting that the age of the plant was not a deciding factor as some of the oldest plants suffered as much as the young ones.

AZALEAS IN GENERAL
        Azaleas are now all grouped together as one series of the overall Rhododendron genus. However, there are now between seventy and eighty species of azaleas and several thousand varieties to give color, contrast, long season of bloom and hardiness.
        One of our early problems was finding sources for different varieties. Now that we're in contact with many good growers and breeders, we know that a better white than 'Snow' and a better pink than 'Coral Bells' are available.
Kurume
        One of the first azalea groups grown in our parks were the Kurume. These are evergreen azaleas originating about one hundred and fifty years ago in the Japanese industrial city of Kurume. They were first introduced into this country at the Pacific Exposition in San Francisco in 1915. Shortly after, many varieties entered into commercial channels principally as pot plants. Most of these early Kurume had Japanese names which were later changed to English - Kirin became 'Coral Bell', Azumakagami 'Pink Pearl' and Suetsumu 'Flame'.
        Currently there are 61 varieties of Kurume growing in our Park, from 'Addy Wery' to 'Yaye-Geri'. They all respond equally to our type of treatment. Selection should be made on color and type of bloom desired. On the bottom of the list would be 'Snow' because its blooms do not fall clean, and 'Coral Bells' for undependable bloom. A better white would be 'H. H. Hume' (U. S. D. A.) and for pink 'Guy Yerkes' (U. S. D. A.)
Kaempferi Hybrids
        The Kaempferi Hybrids are an upright growing group of azaleas, many in our park being over 6 feet high. They are hardier than Kurume and generally bloom later. The flowers are single with a few hose-in-hose and have larger bloom than Kurume. A great deal of the early breeding work in this group was carried on by Dutch nurserymen including P. M. Koster and C. B. van Nes and Son
        There are thirteen varieties growing in Honor Heights Park. The white of 'Annamaria', the pink of 'Betty', and the red of 'Holland Red', all do well with us.
Pericat Hybrids
        These azaleas are the results of the breeding work of Alphonse Pericat at Collingdale, Penn. The parentage is not definitely known, but they may be hybrids between Kurume and Belgian Indian. They were produced primarily for green house forcing, but are as hardy as Kurume and well suited to this area.
        We grow thirteen varieties of Pericat covering the full range of color. White ('Gardenia Supreme'), pink ('Hampton Beauty'), and red ('Hiawatha').
Feldyk
        A Dutch hybrid azalea was originally developed as a hardier evergreen azalea with larger flowers. The flowers range from two to two and a half inches across. All are late mid-season bloomers. Plants are tall and appear to be hardy in this area. First introduced in 1926, but not extensively distributed until 1945.We have four varieties of Feldyk in our Park, all are tall and open in growth. I believe the white of 'Palestrina' is the best.
Glenn Dales
        This is the largest group of evergreen azaleas available to us in Eastern Oklahoma. The original seedlings were grown at the Plant Introduction Section of the Dept. of Agriculture, at Glenn Dale, Maryland. The original idea was to produce varieties that would be hardy in the Washington Area. Mr. B. Y. Morrison did most of the hybridization work and from some 70,000 seedlings over 400 clones were selected and named. Many of these have been lost and others are found only in a few private gardens. Our selection of Glenn Dales contain most of those available to us from commercial channels and a total of just over three hundred. Our plants are from four to twenty-two years old and cover the complete color range and season of bloom of the evergreen azaleas, from April through May, and early June. Date of bloom is much governed by temperature, moisture and shade. For example, during the past ten years, 'Day Spring's' peak bloom has been sometime between March 23rd and April 19th. But it still is one of our earliest to bloom.
        Those that we like best by color and season:

Early April Late April continued
   White - 'Day Spring', 'Festive'

   Red - 'Galathea', 'Beacon'

   Orange Red - 'Ballet Girl'    Pink - 'Fashion', 'Abbott'
   Red - 'Wild Fire', 'Trooper'    Lavender - 'Sambo', 'Nocturne'
   Pink - 'Modesty', 'Morning Star' Early May
   Lavender - 'Seneca'    White - 'Driven Snow', 'Helen Close'
Mid-April    Orange Red - 'Copperman', 'Tanager'
   White - 'Glacier'    Red - 'Pearl Bradford'
   Orange Red - 'Picador', 'Katinka'    Pink - 'Crinoline', 'Peerless'
   Red - 'Red Bird', 'Trooper'    Lavender - 'Chanticleer'
   Pink - 'Illusion' Mid-May
   Lavender - 'Zulu'    White - 'Cadenza', 'Moonbeam', 'Lyric'
Late April    Red - 'Aztec', 'Darkness'
   White - 'Treasure', 'Angela Place'    Pink - 'Pink Star', 'Cremona'
   Orange Red—'Buccaneer', 'Commodore', 'Scout'    Lavender - 'Gawain'

Gable
        The Gable Hybrids are the work of Mr. Joseph B. Gable, a plant breeder of Stewartstown, Penn. His aim was to produce a very hardy evergreen azalea and this he achieved, as Gables are probably the hardiest of all the evergreen varieties. The parentage came from many species but principally R. poukhanense and R. kaempferi. The hybrids selected were generally hardier than either parent and had flowers in color ranging from orange-red to purple and white. There are thirty varieties in our park. Selection by color would be: purple, 'Herbert'; lavender, 'Corsage'; pink, 'Jessie Coover'; red, 'Campfire'; red-orange, 'Stewartonian'; white, 'Rose Greely'; magenta, 'La Roche'.
Chisolm-Merrit
        These were introduced about 1947 and were crosses made by Julian Chisolm of Garrett Park, Maryland. The parent plants were R. kaempferi, Pericats and Kurumes. They bloom early mid-season and are mostly tall growing. There are seven varieties in the park. None is outstanding.
Satsuki
        These azaleas represent a great contribution of Japanese horticulturist to the azalea world. Their very names denote an almost pure Japanese origin. The word Satsuki means fifth month, that is May and June bloomers. They are part of the large group of macranthas. As a group, the Satsuki are more evergreen in character and give the impression that they are more dwarf because of their slow growth. They were originally used in Bonsai work because of their lateral branching. They are given to twiggy growth and a mass of large flowers, some of the largest found on any azalea. In this country, they are often used for border shrubs on the azalea bed.
        We have 52 varieties growing in our Park. Many suffered loss of stems during the 1974 freeze. From those that survived I would select: 'Gumpo', white, pink or rose; 'Heiwa', white with splotches of pink; 'Wakamatsu', white with pink wash; 'Wakabisu', light salmon; 'Eikan', pale rose pink; 'Eikwan', pink with white edge; 'Gunrei', white with pink wash. All of the above except 'Wakabisu' are excellent in tubs or planter boxes.
Back Acres
        After Mr. B. Y. Morrison retired from the Plant Introduction Section in Glenn Dale, Maryland, he went to Pass Christian, Miss. and continued his work. This time he worked toward extending the blooming period, producing doubles that dropped their dead blooms at the end of the blooming period, and selecting clones with white or very light hue centers to carry as a white in the garden effect. There are thirty-five varieties in our park. Like the Satsuki, they suffered much bark damage. And a year later they continue to die back.
        The blooms don't provide much strong color. The exception with us is the variety 'Red Slippers' which is a fire house red.
Southern Indices
        These are the magnificent old plants found in the famous azalea gardens of the south, first introduced into the country over 100 years ago. They were the hardier clones of the Belgian Indian Hybrid. These Belgian Indian Hybrids were the work of early Belgium breeders, originally, produced as forcing varieties.
        We have a few of them growing in Honor Heights Park more or less as trial plants and to widen the azalea field. Most were lost in the freeze of 1974. The following are left: 'Formosa,' 'Jennifer Lynn,' 'Judge Solomon,' 'Pride of Mobile', 'Lawsal,' 'Kate Arendall,' 'Mrs. G. G. Gerbing,' 'Madam Dominique Vervaene,' 'President Claeys' (syn President Clay), 'Perfection,' 'Pride of Dorking.' 
Ryuku
        This group originally came from the Ryuku Island of Japan where they have been under cultivation for more than 300 years. They are a medium-tall plant with single flowers some 3 inches in diameter and are hardy in this area. Those in our collection include: 'Delaware Valley White', 'Ledifolia Alba', 'Sekidera', 'Maxwell', 'Seigal'.
Sawada
        Back in 1927, Mr. Sawada of Overlook Nursery, Mobile, Alabama introduced his first azalea 'Gulf Pride.' He has grown many millions of azaleas since then seeing better color, form and hardiness, chiefly in Kurumes. From some 30,000 seedlings, just four have been named and we have two of them in our garden; 'El Frida,' 'Gloria.'
Macrantha Indicum
        A low spreading dense very late azalea with single 2 inch scarlet-red and violet-red hardy flowers. These bloom off and on during early summer months. We grow 'Orange,' 'Orate,' and 'Red'.
USDA (Beltsville)
        These were introductions of the Horticultural Crops Research Division of USDA during the period from 1950 to 1960. The work was originated at the Beltsville, Maryland Station, by the late Guy E. Yerkes and later by Robert L. Pryor. The initial objective was the production of hardy evergreen azaleas, suitable for forcing by florists and for general garden use. There are sixteen in our collection. Some of the better ones are: white - Casablanca', 'H. H. Hume'; pink - 'Guy Yerkes', 'Rose Banner'; red - Carillon; lavender - Eureka.
Gartrell Hybrids
        These are a new group of evergreen azaleas that we have started in our parks. We haven't had them long enough to give proper evaluation on their merit, but they appear to fill a needed void for hardiness and color, having long blooming period and large flowers. We have 12 varieties in our park. All need further study. We are growing 'Alford', 'Gwenda', 'Lady Dabin', 'Mrs. Updike', 'Mrs. Villars', 'Nancy of Robin Hill', Rosanne', 'Sara Holden', and plants under numbers 0-35-7, N-26-6, T-21-2, V-17-3.
Greenwood Hybrids
        These azaleas were developed by Mr. Bill Guttormsen in an effort to provide another group of azaleas as hardy as the Gables. Our stock came from Island Garden Nurseries in Eugene, Oregon. They are new with us, so we can't tell how they respond to our growing conditions. They are supposed to be hardy to zero and to some subzero weather. We are testing 'Annette', 'Balero', 'Cancan', 'Dolores', 'Greenwood Orange', 'Greenwood Orchid', 'Jan', 'Katie', 'Linda', 'Mona Lisa', 'Puff Pink', 'Red Feather', 'Sleigh Bells', 'Star Ruby', 'Tina', 'Torchlight'.
Linwood Hardies
        Selections made by Fischer Greenhouse at Linwood, N.J. Many were introduced as half hardy greenhousevarieties. Several which have appeared quite hardy here and in Oklahoma City are 'Blush', Cerise, Dark Pink, Light Pink, Orange, Salmon Spray, White, 'Dr. Alderfer'.
Knap Hill
        These hybrids originated with Anthony Waterer about 1870, when a cross was made between Chinese Azalea Mollis and the native American Azalea Flame. Other native azaleas were added to the crosses, but it wasn't until after World War II that they were extensively introduced into this country. We grow 'Copper Cloud'.
Exbury
        This is the name given to a class of deciduous azaleas originating on the estate of the late Lionel de Rothschild, at Exbury, England. Mr. Rothschild obtained his original plants from Mr. Anthony Waterer, a leading English nurseryman. These original crosses were called Knap Hill. As these original plants were distributed they took on the name of the estate where additional breeding work was done. This group has large and spectacular flowers with many beautiful shades of color. Some even have autumn leaf coloration. The color range is from pale pink, carmine, orange, red, yellow, tangerine and white. There are ten varieties in our park covering the complete color range. We found them difficult to handle because of our climate. They will not set buds in the shade, and the foliage burns in the sun, so we settled on early morning sun with noon and afternoon shade. We got good quantity, color and size but no fall foliage color. The following are found in our parks: 'Brazil', 'Bright Straw', 'Cecile', 'Dr. Ray Magruder', 'Fire Ball', 'Firefly', 'Leo (evergreen)', 'Princess Royal', 'Strawberry Ice', 'White Swan'.
Deciduous Species
        In addition to the above listed azaleas, there are a number of species both native American and Oriental to be seen in the park. A great many of them have served as breeding stock for varieties currently on the market. Also, many fine species are very valuable in themselves, either for their woodland character or fragrance. Among these are: R. alabamense, R. austrinum, R. bakeri, R. calendulaceum, R. canescens, R. japonicum, R. nudiflorum, R. poukhanense, R. prunifolium, R. roseum, R. schlippenbachii White, R. schlippenbachii, R. serrulatum, R. speciosum, R. molle.
Miscellaneous
        The following azaleas are classed as miscellaneous because they don't fall into any of the other classes. We have eight varieties of this type. The following do especially well with us: 'Pennington Purple', 'Judd' (Orange), 'Pennington White', and 'Martin's White'.
        Azaleas will grow in Eastern Oklahoma. Success depends on giving them what they need for healthy life - drainage, moisture, and humus soil on the acid side.
        Best of Luck.


Volume 29, Number 4
October 1975

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