JARS v55n2 - Small Rhododendrons from Alfeld, Germany

Small Rhododendrons from Alfeld, Germany
Wolfgang Reich
Alfeld, Germany
Translation from the German by Helga Valigorsky, Pittsfield, Massachusetts

Alfeld is a town in northern Germany located south of Hanover. For rhododendrons, Alfeld is remarkable only in so far as these plants do not grow in the local soil naturally - the heavy clay-lime has a pH of 8.4! However, it is known that people will get an idea in their head for which there seems little prospect of success. Being stubborn and at the age of 45 and of full bodily strength, I started to plug along making the impossible possible, to grow rhodies in chalk soil!

It happened this way: In the middle of the 1970s Tue Jorgensen of Copenhagen, Denmark, showed visitors his rhododendrons, some of which were Rhododendron degronianum ssp. yakushimanum in full bloom and, in a small container, three tiny rhodies with light yellow, pink and purple flowers ( R. keiskei 'Yaku Fairy', R. calostrotum 'Gigha' and R. calostrotum ssp. keleticum ), totally new plants for me, totally different from what I had known so far. This visit was the reason to get more seriously involved with the rhododendrons, and the look of my garden started to change the same year. After my earlier phase of collecting tulips (over 160 species and hybrids) followed by lilies and a successful period of lily hybridization came my first rhododendrons and Ericaceae . They were planted into holes of 20 inches (50 cm) diameter. At first the clay soil was dug out 20 inches (50 cm) deep, the wall lined with foil and the hole filled with a mixture of peat, compost, pine needles and sand. The new rhodies from Jorgensen and Hobbie grew very well in it.

After a few years space got tight, especially since new catalogues from Peter Cox inspired my fantasy anew. Single planting sites were connected to create larger growing areas; the soil had to be renewed. Hauling away the heavy soil, adding loads of peat, pine needles, sand and perlite caused a gradual loss of my steam. By and by the new top layer was reduced from 20 to 16 inches (50 to 40 cm) and finally to 12 inches (30 cm). This did not seem to bother the new plants at all, a dwarf lepidote series with flat root balls from Glendoick. Now after more than twenty years they are fully grown and blooming reliably. I can say that rhodies can grow on chalk soil without problems, however, not in it. The high lime content of many German soils should not be a reason not to grow rhododendrons particularly in small gardens or part of larger gardens. Small gardens are, however, the rule in the more densely populated areas. In the metropolitan regions of larger cities the "leftover" area meant for a garden has gotten so tiny that it compares to an outside seating space with a little greenery around. (In the Munich area the average garden size is from 30 to 350 square yards [27 to 315 sq m].) Nevertheless, the small outside area can offer enough possibilities for various types of gardens if the layout of the property is well planned. Such small areas can be prepared without much effort for rhododendrons and the bushes are "easy care" after the initial planting. A number of Ericaceae and perennials can be easily added as companion plants though requiring under some conditions improved drainage by adding extra sand and gravel.

My experience has been that almost all plants perform well in acidic soil, including alpine plants from dolomite rock. The natural soil there is a humus layer similar to peat; the limestone lies underneath! In contrast acid loving plants will die in alkaline soil; this means: rhododendron soil preparation is optimal for all sorts of plants!

Soon after my purchase of the dwarf species from Denmark, I made my first crosses. These grew well under artificial light in the basement with instructions for their proper care by Tue Jorgensen. But results were depressing after their first winter outside; almost none of the tiny seedlings survived. I had, as one does commonly with other seeds, sown the seeds in the spring. The next planting of seeds happened in October in a friend's orchid greenhouse under plant lights. This way the seedlings had a whole winter and additional growing time after being planted outside by the end of May to get through the first winter; they fared much better.

The seedlings of most lepidotes are only 0.8-1.5 inches (2-4 cm) high after ten months with roots of similar size. The greatest danger of the first winter comes from changing frost and thawing periods lifting the tiny plants out of the ground. If one does not check on the seedlings regularly and pushes them back into the soil, they will sit above the ground and dry out. But if they survive the first outside winter, the battle is won. The seedlings are often strong enough to develop the first blossoms in the third year. This is one of the characteristics of dwarf lepidotes: they often bloom as a very young plant, an attribute making them desirable for small gardens. My goals in hybridizing them are similar to those of other hybridizers: brilliant or new colors of blossoms, increased number and size of blossom, improved hardiness and small size of plant, if possible smaller than the parents. In case of enough seedlings for a selection I will always pick the smallest for further cultivation. Sadly enough, the yield of seeds of a cross of lepidotes is only within F1 forms large enough and between hybrids is extremely low and in many cases sterile.

In the following list I describe my more important hybrids. The first crosses were made in 1978 with R. keiskei 'Yaku Fairy'.

'Reich's Schneewittchen' ( R. minus Carolinianum Group x R. keiskei 'Yaku Fairy'), cross made in 1978, translation of name "Snow White." Five to eight blossoms per truss, opening creamy yellow, fading to pure white after one day. The individual blossom is 1.5 inches (3.8 cm) wide. The plant blooms vigorously and reliably each year by mid-May and is extremely hardy (-15°F [-26°C], the lowest temperature in this region). In a sunny area the foliage becomes purple-red in winter. Plant size is 32 x 24 inches (80 x 60 cm) in ten years.

'Christa Reich' ( R. keiskei 'Yaku Fairy' x R. racemosum ), cross made in 1979. This cross produced slightly variable colors in the seedlings (on opening, creamy yellow or white with pink rim; after two days fading to white). The only distinctly pink seedling, very floriferous (up to thirty-three blooms per truss) was named after my wife and propagated. This hybrid is very hardy (-15°F [-26°C], possibly lower). The plant takes full sun and reaches a size of 30 x 40 inches (75 x 100 cm) in fifteen years.

'Lemon Cloud' ( R. keiskei 'Yaku Fairy' x R. hanceanum Nanum Group), cross made in 1981. As the name implies, the light greenish yellow blossoms (six to nine per truss, yellow group 8C/D) cover the light green mound like a foamy cloud in the first half of May. This hybrid reaches 12 x 28 inches (30 x 70 cm) in twelve years and provides, because of its dense ground hugging growth, a very good ground cover for the sides of stairs, flower beds, walkways and hills. It shows very good hardiness (-15°F [-26°C]).

'Frosthexe' ( R. anthopogon x R. lapponicum ), cross made in 1979 (see photo on front cover), translation of name "Frost Witch." This is so far my most hardy hybrid (at least -15°F [-26°C]) whose blooming time (second half of April) often falls into a period of night frosts in this region. Open flowers can withstand even a week of 20°F (-7°C) without harm. The fairly small bluish purple blooms (0.8 inches [2 cm], six per truss) are close together. The densely growing plant with its coarse, small blue-green leaves blooms floriferously on each branch and attains a size of 20 x 24 inches (50 x 60 cm) in ten years. As a single plant it will become ball shaped. The difficulty with this plant is that all attempts of further hybridization have been without success, a tendency sadly enough shared by other lepidote hybrids. (Only one in ten is successful; the seed yield is very poor, and often only one of the seedlings will prosper.)

'Radhan Baby' ( R. calostrotum ssp. keleticum Radicans Group x R. hanceanum Nanum Group), cross made in 1984. So far my most dwarf hybrid, with extremely dense foliage similar to a dwarf Buxus and flat as a cushion; size is 4-10 inches (10-25 cm) after eight years. The soft pink blossoms on long branches stand well above the foliage and hardly show frost damage since they bloom late May. Hardiness is -11°F (-24°C), buds at -4°F (-20°C). 'Purpur-Geisha' ( R. minus Carolinianum Group x R. campylogynum Myrtilloides Group), cross made in 1984. The parentage of campylogynum shows itself in the long pedicel and bell shaped purple-pink flowers. The plant blooms in the last third of May, is very hardy (-13°F [-25°C]) and reaches 12 x 16 inches (30 x 40 cm) in eight years. However, when standing at an open site protected from full sun, it develops its full bloom which even at a distance is quite striking. This hybrid has shown good potential for further hybridization.

'Mailicht' ( R. minus Carolinianum Group x 'Remo'), cross made in 1985, translation of name "May Light." As the name implies this hybrid gives the impression, even on cloudy days, that the sun is shining on it. The blooming period is May 12-25. The truss (3.2 in [8 cm]) bears up to seven light greenish yellow (4C) to pale yellow green (4D) blossoms each with a diameter of 1.7-1.8 inches (4.2-4.5 cm). The plant reaches a size of 30 x 32 inches (75 x 80 cm) in ten years and is very hardy (-13°F [-25°C]). Since it blooms in the second half of May there is seldom damage by late night frost. There is one problem with this single seedling of the cross: one cannot propagate it easily from cuttings.

'Impossible' ( R. degronianum ssp. yakushimanum x R. dauricum , dwarf form), cross made in 1986. This cross was made in order to challenge my belief that lepidotes and elepidotes cannot be successfully hybridized; the elepidote seed parent chosen on purpose. (Two other crosses of this period [ R. degronianum ssp. yakushimanum x R. lutescens with the typical lutescens leaf and R. moupinense x R. aureum with yellow blooms] proved it possible, although results concerning growth and hardiness were not convincing.) The cross resulted in only four seedlings. Three of them were similar in their habit with 2-inch (5 cm) long blackish green convex curved shiny leaves, typical for R. degronianum ssp. yakushimanum , having five to seven flat, bell shaped flowers of light purple color (81C/D) blooming late April and reaching a size of 20 x 20 inches (50 x 50 cm) after eleven years.

The fourth seedling of this group displayed the habit of R. dauricum prominently with up to fifteen blossoms per truss, each 2 inches (5 cm) wide and of a light purple color (87C/D) inside and light violet (88C/D) outside. Blooming time is the first half of April, the name, 'Incredible' .

Both hybrids are hardy to -8°F (22°C), buds to -4°F (-20°C) but can be easily damaged by frost due to their early blooming time. While 'Incredible' is easily propagated from cuttings, with 'Impossible' it is much more difficult.

'Laurin' ('Purpur-Geisha' x R. pemakoense Patulum Group, RBGE), cross made in 1992, is a newer somewhat taller growing dwarf hybrid (14 x 12 in [35 x 30 cm] in 7 years). The plant, with its light purple (84B/C) in center of lobes, broadly edged strong to light purple (80BD) toward margin, is not only impressive during blooming time (first third of May) but also later because of its dense foliage of shiny oval shaped leaves. The hardiness is 0°F (-18°C). This hybrid in the meantime has one descendant.

'Laurin's Daughter' ('Radhan Baby' x 'Laurin'), cross made in 1992. The flower resembles the male parent; however, the light purple (82D) in center of lobes, broadly edged light purple (81C/D), and outside light purple (81C) give the blossoms a more three-dimensional appearance. The female parent is responsible for the low creeping habit (6.4 x 10 in [16 x 30 cm] in four years). This hybrid was grown an additional winter under artificial lights; it is the only seedling of this cross.

'Inspiration' ( R. minus Carolinianum Group x R. edgeworthii from SBEC 0207), cross made in 1985. This is a repeat of a cross with similar parents as done by the American hybridizer E. Amateis in 1958. The pure white, very large blossoms (3-5 per truss, almost 2.8 inches [7 cm] wide) open at the end of April to the first week of May. Additionally, the shiny, strongly ribbed, lancet shaped leaves and the loose growing habit give this hybrid an exotic appearance. The plant should be allowed to grow freely but needs some protection from frost. Although hardy (plant: -4°F [-20°C]; flowers: 4°F [-16°C]), frost will damage the swelling buds and prevent them from blooming. Only five of fifty seedlings showed the characteristics of the R. edgeworthii parentage.

Another cross with R. edgeworthii is hardier (-8°F [-22°C]), 'Josefa Blue' ( R. russatum x R. edgeworthii from SBEC 0207), cross made in 1988. The medium light violet (91A) flowers with brilliant violet (90C/D) margins are somewhat smaller than in 'Inspiration' (to 2.1 in [5 cm]) but much more floriferous with up to eight blossoms per truss. The plant blooms in the first half of May and grows more tall than wide (30 x 20 in [75 x 50 cm] in six years). The leaves are oblong-lanceolate, convex, dull moderate olive green above. This cultivar is also from a single seedling.

'Dörte Reich' ( R. minus Carolinianum Group x R. cinnabarinum ssp. xanthocodon Concatenans Group), cross made in 1984. The goal for improved hardiness for the R. cinnabarinum group was successful in this hybrid with a hardiness rating of –11°F (-24°C), this without changing the appearance of the blossom shape (tubular, slightly pendent). The plant has been blooming reliably since 1992 with up to six light reddish purple to moderate purplish pink (74C/D) blossoms per truss, with a deep purplish pink (61D) throat. The size is 60 x 44 inches (150 x 110 cm) after fifteen years.

Remarkably smaller is a new hybrid: 'Goldschopf' ('Woodchat' x R. fletcherianum ), cross made in 1990, translation of name "Golden Tuft." The intense yellow, slightly bell shaped flowers indicate the parentage of R. ludlowii . The 1.9 inch (4.8 cm) blossoms are five to six per bell shaped truss. Since the blooming time is the first third of May, a somewhat protected area is advised. The plant has reached a size of 10 x 14 inches (25 x 35 cm) so far and has withstood 1°F (-18°C) without damage. We did not experience lower temperatures since then (1990).

'Charmant' ( R. ambiguum x 'Burnaby Sunset'*), cross made in 1990). By including R. ambiguum the cross led to increased hardiness (-8°F [-22°C]) and to more flowers (up to nine per truss of almost 2 inches [5 cm] diameter). The color is light yellowish pink (red 36B), overlaid with orange (27A), with translucent yellow green speckles. The plant blooms in the second half of April and grew to 34 x 32 inches (85 x 80 cm) in nine years.

'Frechdachs' ( R. campylogynum Celsum Group x R. keiskei 'Yaku Fairy'), cross made in 1993, translation of name "Cheeky Rascal". So far my latest hybrid appearing bright and pert with its bi-colored flowers, about five blooms of 1.8 inch (4.5 cm) diameter with strong to purplish pink inside (54C/D, uppermost lobe spots deep purplish red (61A) with speckles, the outside being strong purplish red (63A/B) fading to strong purplish pink to light purplish pink (63C/D) towards the rim. Blooming time is between the end of April and early May. Hardiness so far –8°F (-22°C), size after six years 14 x 18 inches (35 x 45 cm).

Propagation from cuttings is not difficult for those hybrids with the noted exceptions.

Kenneth Cox of Glendoick Gardens Ltd. has received rooted cuttings of most of these hybrids for testing.

* Name is not registered.

Mr. Reich has been a member of the ARS since 1986 and a member of the German Rhododendron Society (Deutsche Rhododendron Gesellschaft) since 1984.