JARS v40n4 - Rhododendrons Of North Germany

Rhododendrons Of North Germany
The Rhododendron Park - Bremen - 1936-1986 - 50th Anniversary
Jon M. Valigorsky, M.D., Pittsfield, Massachusetts

Dr. Valigorsky is an Associate Professor of Pathology, University of Massachusetts Medical School, Berkshire Medical Center. Currently Chairman of the Massachusetts Chapter display garden at Stanley Park, he also is a rhododendron hybridizer working towards the goal of obtaining yellow and red elepidotes hardy to -20°F with 2500 seedlings in the fields for evaluation.

This article is the second of two written by Dr. Valigorsky on "Rhododendrons of North Germany". The first appeared in the ARS Journal Vol. 39:2, Spring 1985 , This article, originally printed in the "Rosebay", Fall 1984, has been extensively rewritten by the author for the ARS Journal.

From May 22 to May 25, 1986, coinciding with the annual meeting of the American Rhododendron Society in Cleveland, the German Rhododendron Society met in Bremen to celebrate a double anniversary: The 50th Anniversary of the German Rhododendron Society founded in Bremen, October 18, 1935 and the 50th Anniversary of the great Rhododendron Park - Bremen, 1936, to 1986. A congratulatory telegram was sent from ARS President William Tietjen on behalf of the entire membership to Hans-Andre Schultz, President of the German Rhododendron Society.
Since 1981 my wife Helga and I have been members of the German Rhododendron Society and have enjoyed an active correspondence with Dr. Lothar Heft, Director of the Rhododendron Park in Bremen. On his invitation we visited the park in late August of 1983 and again in May 1985.
Bremen is a city with a rich heritage. Established in 787 A.D., actually it is a city/state, the smallest in West Germany. It lies on the Weser River 83 miles distant from the North Sea. As one of the original members of the Free Hanseatic League it is one of West Germany's busiest seaports.
The right of men to pursue commerce freely with a minimum of government control is deeply ingrained in the North German character. The investment of the fruits of such commerce toward the betterment of the society is a concept we inherit from these city/states of the Hanseatic League. The founding of the Botanical Garden and Rhododendron Park draws heavily on this tradition.
The 90 acre site lies on the southeastern outskirts of the modern city in the section called Horn. In the late 19th century this tract belonged to the Bremen ship owner and merchant Willy Rickmers. On this site he established a wildlife preserve and a deer park. In its native state it consisted of a stand of oaks, beeches and ash. To these native European species were added many examples of American oaks. The growth of the city encroached on the site and, in 1911, the tract became the property of Bremen.
In 1935 a group of rhododendron hobbyists and nursery tradesmen registered the charter at the Bremen "Rathaus" for a rhododendron organization, thus forming the German Rhododendron Society. Also in this year the rhododendron nurseries of Oldenburg, 50 kilometers to the west of Bremen, proposed that a test garden be created for rhododendrons, for the purpose of informing the public as to what varieties could successfully be cultivated. The decision was made by the Bremen Parks Department under the guidance of its director Richard Homann: Willy Rickmers' Deer Park became the Rhododendron Park. The initial test garden comprised five acres and plants were begun in 1936.
In 1937 the German Rhododendron Society had its first formal meeting at the park. The society joined forces with the nursery industry and made a major commitment to the development of the park not only as a test garden but enlarged its scope as a display garden growing the widest possible variety of species and hybrid rhododendrons. The Rhododendron Park is a cooperative venture between the Municipal Parks Department of the City of Bremen, the Rhododendron Nursery Industry and the German Rhododendron Society. Johann Berg served as director from 1936-1967, to be succeeded by Dr. Lothar Heft. Thus, only two men have guarded the development of the Park in its 50 year history.

Dr. Lother Heft
Dr. Lother Heft, Director of the Rhododendron Park, Bremen, standing
beside some of his F2 R. yakushimanum x
R. wardii hybrids.
Photo by Jon M. Valigorsky

This is, however, a tale of two gardens. To complete the history of the founding of the park, another Bremen ship owner, Franz E. Schuette, is of central importance. He owned a fleet of tankers and imported oil from Texas and Mexico. His ship captains were ordered to bring back native plants from these lands. In the center of the city, on the east dike in 1905, he founded a private botanical garden open to the public. This existed until 1935 when the city ordered it closed. The people of Bremen vigorously protested and in 1937, on the site of the Rhododendron Park, the Botanical Garden was established. There was ample space since the original rhododendron display comprised only five to six of the 90 acre site.
The first meeting of the Botanical Garden was in 1938 but as World War II intervened, construction of both gardens came to a halt, to resume in 1948 to 1951 when the site was designed and the layout implemented. Forty-six acres comprise the Rhododendron Park and eight acres the Botanical Gardens. Two and one-half acres is devoted to a heather garden and a preserved natural woodland completes the remaining 18 acres.
The two main gardens lie south of an old carriage road barely nine feet in width which originally connected the central city of Bremen with the rural summer houses of the merchants. The heather garden, the Rhododendron Cafe and the extensive glass houses lie north of this carriage road. It now functions as a service road for the gardens. To the far south, the main entrance of the park is from the major thoroughfare, Marcusallee.
The Botanical Garden today is comprised of the following: 1) an herb and medicinal garden; 2) habitat gardens containing all the flora of a region — this is broken into geographic sections for North Germany, North America, East Asia, Australia, the Mediterranean, and a section for alpine flora in the rock garden; and 3) the heather garden. In addition there are extensive plantings of annuals and perennials on a grand scale as a show garden to stimulate the home gardener. A rose garden is in the planning stage.

A Tour of the Rhododendron Park: The major display areas include: 1) the formal species display garden; 2) the formal hybrid display garden; 3) the Rhododendron Cafe and the heather garden; 4) the glass houses; 5) the rock garden; 6) a newly developed hierarchical planting of deciduous azaleas and their hybrids and 7) a special planting of American elepidote hybrids.
Inside the main entrance of the park are the initial plantings from the 1930's, now well over 50 years old. These include primarily the English developed ironclad hybrids and early English and Dutch hybrids. Set amongst the background of ancient European beeches and oaks these plantings remain perfectly in scale. Sited along both banks of the slow flowing canal, which traverses the park, these 15 to 20 foot high ironclads are a dazzling display in bloom. Vast plantings of yellow R. luteum and orange azaleas occupy islands and reflect their brilliance in the waters of the canal. Proceeding east, the high density plantings near the entrance then give way to more open plantings of rhododendrons in large masses surrounded by lawn again with towering oaks and beeches providing the over-story. The effect is ever changing vistas on a truly magnificent scale. Proceeding north one eventually reaches the "Sortiments Garden" consisting of two large collections, one of species and one of hybrids.

The Formal Species Garden:
This was begun after the war when diverse plantings were centralized at this site. They are arranged according to Balfourian series. All plants are comprehensively labeled. The collection includes fine mature examples of R. sutchuenense , discolor , wardii , oreodoxa , taliense , adenogynum , campanulatum and many others. A magnificent Rhododendron oreodoxa , forms a massive twelve foot high dome. The canopy of an R. sutchuenense var. geraldii spans at least 25 feet and is certainly more than 50 years old. A new discovery for us was R. clementinae exhibiting its upright round growth habit, magnificent foliage and highly ornamental new growth. This is flanked by superior forms of R. campanulatum var. aeruginosum selected from several hundred grown at the park from seed. Also present are many fine examples of R. brachycarpum var. tigerstedtii also grown from the seed in the park. The seed came from Nizelius in Goteberg who described this variant with its large heavy textured leaves and thick stems, contrasting with somewhat disappointingly small trusses. Truss size, however, is variable and Dr. Heft assured me that many superior forms with larger trusses could be found elsewhere in the park. Other related species include a very good rose form of R. fauriei . Excellent forms of R. wardii both Ludlow and Sherriff and R. puralbum are evident. R. dichroanthum ssp. scyphocalyx survived the -11°F recorded in the park the previous winter to bloom with full trusses.

R. clementinae R. campanulatum var. aeruginosum
Species garden, R. clementinae .
Photos by Jon M. Valigorsky
Species garden, R. campanulatum
var. aeruginosum with R. luteum
in the background.

The Formal Hybrid Garden:
This consists of nineteenth and early twentieth century hybrids from North Germany, Holland and England. Their arrangement is alphabetical by name. The collection is most interesting in that it allows comparison of varieties previously in commerce with varieties currently propagated.

The Glass Houses:
Preceding in a westerly direction along the old carriage road one comes to the glass houses. The first, the Wilhelm Kaisen House, was erected in 1972 and consists of three major sections. A west house is used for the cultivation of rhododendrons of the Vireya section; the large central and smaller south sections are devoted to tropical and subtropical rhododendrons. Under glass in the three houses, is an area of 969 square meters with the central house 11.65 meters or 38 feet in height as its peak. In the central and south houses are rhododendrons from Central Asia, the Himalayas, Burma, Tibet, China, Formosa, and Southern Japan.
An eight foot tall specimen of R. griffithianum growing in a container is at the entrance. Once inside, one is overwhelmed by the great collection of species of the Falconeri and Grande series and magnificent specimens of Rhododendron giganteum and Rhododendron sinogrande . Two hundred and fifty species are under cultivation here.

R. hodgsoni R. magnifìcum
Glass house, R. hodgsonii
Photo by Jon M. Valigorsky
Glass house, R. magnificum
Photo by Jon M. Valigorsky

In the west house a great variety of vireyas are planted growing in a variety of media, including fern logs and peat blocks. These are under conditions of almost 100% humidity. We saw Rhododendron zoelleri and 'Dr. Herman Sleumer' in bloom.
In 1974, through an initial grant from the German Rhododendron Society and a bequest from an anonymous Bremen merchant, seven additional glass houses were constructed expanding the total floor area, under glass, to over 1,800 square meters. These were opened in April of 1974 by a formal exhibit from three of the best known rhododendron nurseries: G.D. Böhlje, Joh. Bruns and D. Hobbie. Also on permanent exhibit were the newest hybrids from the United States and England. A portion of these facilities now are devoted to plant propagation from cuttings, grafts and importantly, from seed. One house is totally devoted to fuchsias, providing an impressive display of over 100 varieties.
Dr. Heft demonstrated the redundant heating system consisting of the main system and a completely duplicated back-up. Behind the glass houses large, above ground, storage tanks hold a three year supply of fuel oil. Dr. Heft noted that he keeps a close eye on the nearby Rotterdam spot market.

The Rhododendron Cafe:
A stop at the Rhododendron Cafe adjacent to the glass houses provides a respite for weary feet and needed hydration. Beds of meticulously labeled alpine rhododendrons border the entrance. A most spectacular sight in August is the heather garden in full bloom stretching in a vast meadow just beyond the cafe terrace.

The Rock Garden:
One of the wonders of the Rhododendron Park is the Rock Garden. Fully one acre in size, it was begun in 1972. It was built using largely the labor of the park staff. Dr. Heft admits, had he realized the enormity of the task, he would have never attempted it. Construction encompassed four long years and was completed in 1976. Portions of the Rock Garden are constructed using surplus paving stone salvaged from municipal yards. Initially, larger granite boulders were placed by hand using a tripod arrangement. Later it was necessary to bring in large cranes along the old carriage lane.

R. camtschaticum
Rock garden, R. camtschaticum.
Photo by Jon M. Valigorsky

The Rock Garden is its overall layout and design is a masterpiece. One can view the plantings from all possible aspects. At one entrance to the Rock Garden is a mass planting of R. yakushimanum grown from seed followed by a mass planting of mature R. aureum . These are essentially at ground level and as one ascends along a path well above the plantings, vast beds of R. camtschaticum provides a spectacular display which begins in May and continues throughout the summer months. Descending then through passageways in the Rock Garden, one encounters many of the smallest dwarf species at eye level, the ideal perspective to view these plants. This includes R. keleticum , impeditum and williamsianum , and many others. Again, all plants are comprehensively labeled. The Rock Garden is shared with the Botanical Garden and encompasses almost all species of alpine flora.
On the back or shady side of the Rock Garden is a large planting of R. forrestii var. repens . This is surrounded by its hybrids, a testament to Dietrich Hobbie.

Other Areas of the Garden:
With Dr. Heft as our guide we toured a secluded and secure large nursery holding area in which plants for future display are grown on. The objective is to grow a plant to a size large enough that it would require two large men to move it. This is a principle theft deterrent.
For those travelling to the Park by car, a parking lot is located at the western side of the Park on Deliusweg. This entrance is dominated by a formal planting of rhododendrons grouped into three assortments.
First is the Seidel assortment. T.J. Rudolf Seidel, the most prominent member of the Seidel family, hybridized rhododendrons in Dresden from 1880 to 1916. Dresden, located far inland in East Germany, is considerably colder than Bremen and Seidel used R. catawbiense and R. smirnowii as sources of hardiness. According to Dr. Heft, he sowed his seeds outdoors directly onto the ground. Undoubtedly this accounts for their great vigour. This assortment includes the best of the Seidel hybrids: 'Bismarck', a pink fading to white; the reds, 'Scharnhost', 'Raphael' and 'Holbein'; the purple 'Humboldt' and 'Leopold'; a pink 'Omega'.

R. 'Omega'
Seidel collection, 'Omega'.
Photo by Jon M. Valigorsky

A second group is the rhododendron hobbyist assortment. This includes the incomparable 'Furnivall's Daughter', the Hanger hybrid 'Renoir', 'Adriaan Koster' and 'Scintillation'.
Finally, a third group is the so-called standard assortment of the mainstays of the nursery trade including: 'Album Novum', 'Nova Zembla' and 'Catawbiense Grandiflorum'. Opposite these plantings is the original azalea museum which depicts the history of the development of the hybridization of Indian azaleas since 1840 and provides a peak display in April. A new azalea museum adjacent to the glass houses opened this year.

The Azalea Walk:
In the southeast section of the Park just to the east of the headquarters building of the German Rhododendron Society and Dr. Heft's office is the most recently developed mass planting, the deciduous azalea walk. More than 15 years has gone into the planting and execution. The walk is arranged in a hierarchy beginning with the deciduous species grown at the park from diverse seed sources which illustrate the often extreme variation within species. Beds of R. vaseyi , periclymenoides , prinophyllum are followed by R. japonicum showing the tremendous variation from multiple sources, followed then by the Mollis or Japonicum hybrids totaling 120 varieties. There is a planting of Rhododendron occidentale followed by a fine large collection of 77 Ghent hybrids and finally 114 of the Knap Hill, Exbury, IIam and Windsor hybrids and the more recent Dutch and German hybrids, many of the latter from Mr. Hachmann. Plantings are in border beds surrounded by lawn and towering beeches.

The azalea walk, Knap Hill, Exbury section.
The azalea walk, Knap Hill, Exbury section.
Photo by Jon M. Valigorsky

American Hybrids:
Just beyond the azalea walk is a large planting of American elepidote. The early Shammarello hybrids are well represented including large plants of 'EIie', 'Holden', 'Lavender Queen', 'Cheer', 'King Tut', 'Belle Heller', 'The General', 'Spring Dawn' and 'Sham's Ruby'. Cable is represented by a plant of 'Atroflo' and perhaps others that we did not locate.
Surprisingly, the largest group of American hybrids are Dexters. This included good sized plants of 'Avondale', 'Aronimink', 'Accomac', 'GiGi', 'Scintillation', 'Dexter's Orchid', 'Parker's Pink', 'Westbury', 'Sky Glow', 'Tom Everett', 'Betty Hume', 'Mrs. W.R. Coe', 'Nathan Hale', ' Dexter's Appleblossom' and 'Wyandanch'. In addition, plants of 'Wheatley', 'Brookville' and 'Roslyn' are present. These are growing in the far southeastern boundary of the garden in an area where there is ample space for additional display plantings.
Of the slightly over 1,000 rhododendron species, 680 are in cultivation in Bremen. There are 960 varieties of rhododendron hybrids. Finally, more than 600 varieties of evergreen and deciduous azalea species and hybrids comprise the plantings of the Bremen Rhododendron Park, in its totality, the largest collection of rhododendron and azalea varieties grown anywhere in the world.
As to cultural conditions, the soil ph ranges from 4.8 to 5.5. The soil has a high sand content with a high percolation rate. This is enriched by leaf mold. However, parts of the garden contain dense clay and there are other areas with pockets of loam. Beds are carefully prepared by spading in large amounts of leaf mold.
At least three plants of each variety are set out. These again are large enough plants requiring two men to move and are planted in a triangle, 1 to 2 meters apart, to insure that eventually they will grow together creating the appearance of a single plant. Should one plant die the overall plan of an area is not altered and the display remains intact. Careful attention is devoted to grouping colors harmoniously together. These groups are then further broken up by spot plantings of whites throughout the beds.
The principle means of identifying plants is by 18" tall wooden stakes. Plants are also identified by heavy metal tags and are further identified on a coordinate map of a given planting area. The wooden stakes are removed after the blooming season and are set out again in the spring.
In the 1983 visit North Germany was experiencing the worst period of drought in 200 years. Dr. Heft's staff of 36, including 16 master gardeners, had devoted much of the summer to watering the extensive plantings using portable gasoline driven pumps. Indeed, despite the drought, the plantings were in excellent condition. In 1985 North Germany had experienced its worst winter in perhaps 100 years with a record low temperature in Bremen of -11°F. Once again only scattered damage was seen in tender types.
This, one of the foremost rhododendron gardens in the world, is reflected in the dedication and infectious enthusiasm of its director, Dr. Lothar Heft. He, perhaps, best characterizes himself as a rhodoholic. Under his direction one is impressed as to the extraordinary way the cultural requirements of diverse species had been satisfied resulting in such superior well-grown specimens.
Dr. Heft's own hybridizing has employed R. yakushimanum . At one time he had over 5,000 seedlings in cultivation with many of his most promising crosses with R. wardii . He has progressed to the F2 generation. Ten selections, which are both indumented and yellow, remain.
He has made three trips to Nepal, in 1978, 1979 and 1982, to gather plants, scions and seeds. There now are several races or forms of R. arboreum in the glass houses. He decries the loss of habitat secondary to the clear cutting of the mountainsides in Nepal. Even in the natural preserve and Botanical Garden of Kathmandu, one can stop and hear the "chop-chop" of wood gathering.
His major goals remain the continued expansion of the garden, both species and hybrids, with an emphasis on expanding even further the variety of species under cultivation. Specifically, he is assembling, from diverse sources, additional hybrids of European hybridizers working in the late 1800's and early twentieth century. An example is Seidel of Dresden. He is quite interested in obtaining additional lepidote hybrids as developed by Edmund Mezitt. The three originally named 'PJM' clones are the extent of the collection thus far. Finally, an azalea display garden is planned in conjunction with the Botanical Garden.
Our deep gratitude is extended to Dr. Heft and his gracious wife for two most wonderful visits and to Herr Bischoff, his head gardener and Frau Schaade who is in charge of the glass houses.
The Bremen Rhododendron Park and Botanical Gardens operates so successfully on so many levels. For the casual visitor, the citizen of Bremen and the lay person it provides an oasis of relaxation on a Sunday afternoon. For the amateur and advanced gardener it provides a storehouse of information on what will grow and how to grow it. For the rhododendron enthusiast it is all of the above as well as a scholarly experience. Peak bloom is May 15 to May 30.