Azaleas at Lindum Gardens in Portland
Irving B. Lincoln
In the months of April and May five thousand deciduous azaleas in forty of the world's finest varieties shine out in a "Blaze of Glory" in Lindum Gardens on Skyline Crest overlooking the Tualatin Valley. A riot of colors, ranging from the softest creams through the brightest yellows and oranges and the fieriest reds, march in mass formation up and down the hillsides. These brilliant gems are held in a luminous setting, flanked on both sides 'with a galaxy of over 250 of the finest varieties of Rhododendrons resting in little cups among the birches on the hillsides, and on the West is the broad expanse of the checkered Tualatin Plains rising to the mountains in the distance. Imported from the gardens of Europe, these choice varieties are now available to join the splendor of our Oregon flowers.
Where Planted: Azaleas are sun loving plants and are planted on the wind-swept terraces in the blazing sun. They like plenty of water, good air and water drainage, sunlight and a humus, acid, porous soil. This corresponds to the bleak, wind-swept, sunburned mountainsides of Asia, which is the natural habitat of many of their forbearers. They will stand the strongest winds, if not laden with ocean spray. In shade they are less healthy, with weak, spindly,. open-headed growth and few flowers. In full sun and not too much fertilizer they make a short, compact growth with plenty of twigs, tipped with flower buds which in the Spring burst into a mass of blooms.
Soil and Fertilizer: The soil on my nursery is the bed of a virgin forest with the accumulation of generations of leaf mold from the logged-off conifers. This has been improved by the addition of plenty of peat moss, rotten sawdust, compost and other humus. It is naturally acid. Deciduous Azaleas need very little commercial fertilizer. Too much fertilizer stimulates rank growth, large leaves, water sprouts and fewer buds. The long sprouts need to be cut back and made to branch out.
Like most surface feeding plants, Azaleas like a porous soil with air in it, plenty of water during the growing, bud-forming period, but no stagnant water to drive the air from the soil around their roots.
In producing or maintaining an acid soil, aluminum sulphate or sulphur or a mixture of both is beneficial, although if plenty of peat moss, compost and leaf mold are used in the soil, it will be naturally acid. Aluminum sulphate acts immediately, but sulphur takes a little time to become available. Rotten sawdust is good as a mulch, but if it is mixed with the soil, it uses nitrogen from the soil during its decomposition and this should be replaced or you will get stunted growth and yellowish shaded leaves, especially on the Rhododendrons. - Ammonium sulphate or ammonium phosphate are good to replace the nitrogen taken by the decomposition of the sawdust. Rotten cow manure can be used as a mulch, but if much is mixed in the soil, it will form an alkaline soil, and some acid should be added.
In preparing the soil in the pockets on the hillsides for both azaleas and rhododendrons, I take off the top soil, dig out the clay subsoil to a depth of 18-20 in. and then fill in to ground level with a mixture of half peat moss and half top soil or a mixture of garden compost, rotten sawdust, peat and top soil so as to get a porous, humus, acid soil. On the hillsides the pockets in which the plants are set are 3 in. in diameter. In the level azalea beds on the terraces, the soil is mixed with the above ingredients as in any flower bed.
New Persistent -Leaved Varieties: The new persistent-leaved varieties, Malvatica and Vuykiana hybrids, however, may have better blooms in part shade, as their blooms may be faded by the constant rays of full sun. However, they will grow well in full sun. These persistent-leaved varieties, I believe, can also take more fertilizer. But the fast and tall growing branches should be cut back to force out side branches.
Suckers: Most of the varieties are on their own roots, having been propagated from layers. A few of the choicest, hard-to-get varieties are grafted, and if suckers come up from the roots of these, they need to be cut out or you will have two shades of colors in the flowers. Fast growing shoots called water sprouts also shoot up. These can be cut back and forced to branch out.
Varieties: There are the occidentale hybrids, the Ghent azaleas, the Mollis hybrids, the Rustica Flore Pleno (Hose-in-hose), and the species plants. In the persistent-leaved azaleas there are the new Malvatica hybrids (crosses of Malvatica and kaempferi azaleas and 'Hinode-giri' and kaempferi azaleas) and the new Vuykiana azaleas.
Azalea Ratings: The Rhododendron Handbook of the Royal Horticultural Society for 1947 gives azaleas their ratings, but they have not covered azaleas so long or so thoroughly as they have rhododendrons, and their ratings are not complete. Many of the best varieties have no rating at all, but for the older varieties, it is a guide. The highest rating in Azaleas is three stars, and there are only two varieties in this class. Most of the best varieties have one or two stars, although there are some varieties like 'Hamlet', which I consider one of the best, which has no stars at all.
Ghent Hybrids: The hybridizing of azaleas seems to have taken place more in Holland and Belgium than in any other countries. Those at Lindum Nursery are practically all imported from Holland where they specialize in breeding and propagating the finer named varieties. As far back as 1825 the hybridizing of azaleas was started. A baker in Ghent, Belgium, by the name of P. Mortier crossed the native European azalea with those from Eastern North America. Later other varieties from Asia and Western America were added, including R. occidentale , R. molle and R. japonicum . All of these varieties were crossed and re-crossed until it is now almost impossible to trace any one of the Ghent or occidentale hybrids to its original parents. All Ghent hybrids are hardy. What are known in the trade as Pontica hybrids or hardy Ghent azaleas have a wide variety of strong colors both in true colors and variegated forms. They are red, orange, yellow, light yellow, white, copper, bronze, pink, crimson, mauve and purplish red and others. The varieties of Ghent azaleas which I consider best of those in my display are 'Unique', 'Gloria Mundi', 'Coccinea Speciosa', 'Daviesi' and 'Pallas'. There are other varieties that come in as close seconds. 'Unique' and 'Coccinea Speciosa' are a strong, bright orange, like a real ripe orange in prime condition. 'Gloria Mundi' is more of a spreading plant, later, and in color a little softer with a mixture of yellow and orange and a little cream. It is one of the latest of the azaleas to bloom and one of the best. 'Daviesi' is white with a light yellow marking.
Occidentale Hybrids: This breed of azaleas are crosses of our Southern Oregon native azalea with Ghent hybrids and other which have formed one of the loveliest groups of plants. They are fragrant and their colors are softer than the Ghent or Mollis hybrids. The flowers are larger and more abundant than those of our natives, and the masses of blooms have a wider range of colors - each variety true to its color and time of bloom. The varieties are 'Irene Koster', 'Graciosa', 'Delicatissima', 'Exquisita', 'Magnifica' and 'Superba'. The first into bloom of the occidentale and one of the early azaleas is 'Irene Koster', a soft, light, lovely pink-one of the best. 'Graciosa', in mid-season, brings on more of a contrast of colors-creamy pink marked with orange and yellow. Then there is 'Superba', a deep pink with a yellow and apricot blotch. 'Delicatissima' is a cream with a yellow eye and a pink tinged bud, late. 'Exquisita', coming at about the same time as 'Delicatissima', is a creamy pink with an orange blotch. 'Magnifica' is creamy white flushed pink. All of these occidentale hybrids are among the finest azaleas grown and have two star ratings.
Molle-Japonica Hybrids: The Chinese azalea molle has been crossed with the Japanese azalea japonicum and others to form the Mollis-sinensis, or more properly the molle-japonicum group. They are sturdy, fool proof plants, 3 ft. to 6 ft. in height. These plants have very bright, fiery-colored flowers which in the named varieties have true colors and uniform habits. They range in color from yellow and cream to the fieriest reds. I have fifteen of the finest hybrid varieties in my nursery, all given high ratings by the Royal Horticultural Society. There is 'Adriaan Koster' and 'Marmion', the only three star plants in the book. Both are clear yellows, 'Adriaan Koster' a little deeper yellow than 'Marmion'. 'Directeur Moerlands' (Golden Sunlight) is a rich golden yellow, which in Holland is thought to be a better plant than 'Adriaan Koster'. It is under trials at the Wisley gardens of the Royal Horticultural Society. 'Hamlet' and 'Floradora' are large flowered orange blooms with a large, dark blotch making a striking contrast. 'Evening Glow' is a large, flowered, glowing red. 'Dr. M. Oosthoek', given an award, of merit and a two star rating by the Royal Horticultural Society, has dark, fiery, mandarin red blooms, of good size that do not burn. It has a free flowering, bushy habit. 'Koster's Brilliant Red' is one of the first to bloom, and its flowers are long lasting, being over a month in bloom, and in the Fall its red leaves stay on the longest. It has a two star rating and is a glowing orange-red. 'Koster's Yellow' is a clear lemon yellow on a, par with 'Koster's Red'. 'C. B. Van Nes' and 'Spek's Brilliant' are two outstanding fiery reds. 'Babeuff' is a two star bright salmon shaded orange. 'Clara Butt' is a two star deep pink and 'Multatuli' is a glowing orange red. Others on the list include 'Koster's True Red', 'Queen Emma', 'Lemonora', 'Prof. Amundsen', 'Christopher Wren' and 'Mrs. G. Van Noordt', a large flowered salmon pink. All of the Mollis-Japonicum hybrids are hardy, seldom failing to produce a blaze of color in the Spring and rich red foliage in the Fall.
Rustica Flore Pleno (Hose-in-Hose): This group is all double flowered. 'Il Tasso' is the first to bloom and is a solid colored rosy red with star-like flowers. 'Norma' is pink with darker shading and creped. 'Aida' is a rosy pink with darker margins. 'Corneille', a most beautiful pink and white variegated flower, has a refined charm that makes it distinctive.
Malvatica-Kaempferi Hybrids: This comparatively new group of plants of European origin has hairy, persistent leaves but is included here because it is outstanding, new and different from the evergreen plants in general use, and is considered the best hybrid Azalea of recent introduction. In color they range over the different shades of pink, dark pink, rose, brick red, salmon pink and ,orange. In size they will grow to four feet with a spread of more than that and are rounded open shrubs that will stand pruning as they get older. In Spring they are a solid mass of blooms. They are rated among the best of the azaleas, with two stars given by the Royal Horticultural Society. The crosses of Malvatica (an obtusum hybrid) and kaempferi give several fine varieties. 'John Cairns', an Indian red two star plant, was given an award of merit in 1940 and is one of the best. 'Pink Treasure' is a clear, true pink. and near the top in choice. 'Betty' is orange pink and 'Fidelio' is deep rose pink. 'Anny' is orange red, 'Jeannette' is rose-red and 'Willy' is clear pink. This new group of plants is destined to take a place of importance in our gardens. All grow in full sun. 'Orange Beauty' is another new plant. It is a cross between 'Hinodegiri' and kaempferi . It is a soft orange and was given two stars and an award of merit in 1945.
Vuykiana Hybrids: This new group is supposedly a cross between the evergreen Kurume and the Mollis azaleas. There are several varieties, but the outstanding plant is the two star white with a faint green marking named 'Pauestrina'. It is very strikingly displayed as an edging of white with Rhododendron 'May Day' on the estate of the late Lionel de Rothschild at Exbury, England. 'Palestrina' is also fine as a plant for forcing.