Rhododendrons are descended from the Magnolias through the Camellia and Dillenia families. They belong to the family Ericaceae. Their floral parts are typical of those of primitive plants. Fossil records show that rhododendrons existed in Europe and North America some 50 million years ago, essentially in the same form as the wild ones in Asia; a few of these still exist in America (Asia and America were once contiguous).
Rhododendrons were recommended as garden plants as early as 1629, but the naming of the few then known was chaotic. Linnaeus, in 1753, brought some order to the nomenclature of the genus, but excluded azaleas. Nowadays, azaleas are included as a botanical Section of the genus rhododendron.
The first species to be introduced to cultivation in Britain, in 1656, was R. hirsutum, from the European Alps. This was followed, over the years, by a few others until, in the early 1760's, the now dreaded (invasive) R. ponticum appeared. It was succeeded, in 1811 by the blood red flowered R. arboreum, a tree rhododendron, hybrids of which grow in the woodlands at Portmeirion. R. molle arrived from India in 1811. It has, depending on its origin, yellow, orange, pink or red flowers, and it gave rise to the R. molle ssp. japonicum series, widely grown under the name Azalea mollis. In 1835 the scarlet R. barbatum was discovered in the Himalaya, and imported into England.
Then followed a host of introductions from the early explorers: 1850, Joseph Hooker in the Himalaya with, amongst others, the yellow R. pillocarpum, and in 1856, Robert Fortune in China with the pink R. fortunei, later notable for its importance in hybridisation. By 1900, about 200 species were known.
Later plant hunters added even more. Thus from 1899 to 1918, E H Wilson in China, from 1904 to 1932, George Forrest in China, from 1914 to 1920, Reginald Farrer in China and Burma, and from 1911 to 1930, Frank Kingdon Ward in China and then in Tibet, Burma and Assam, collectively added more than 600 new species. These, and others, are classified in: Rhododendrons of the World by G Leach. Other useful texts in this area are Rhododendron Species, Vol. I, Lepidotes, and Vol II Elepidotes, by H H Davidian, Batsford, London
respectively 1982 and 1999 [lepidote : scurfy with minute scales ; elepidote : without scales] and Rhododendron Hybrids (A Guide to their Origins) by H E Salley and H F Greer, Timber Press, Portland, Oregon, 1986. Modern nomenclature is too complex to be dealt with here, but it is explained in: The Encyclopaedia of Rhododendron Species by Peter A Cox and Kenneth N E Cox, Glendoick Press, 1997 and also in: Rhododendrons by D M van Gelderen and J R P van Hoey Smith, Batsford, London 1992.
Amongst Kingdon Ward's most notable introductions was R.wardii, with yellow flowers and superb form. He was still exploring in 1953 in the North Burma triangle. Kingdon Ward was a man of great spirit and determination. He died in 1958. For an account of life with him, see Jean Kingdon Ward's article 'Living Investment' in The Garden, 2001, 126, 200.
The first hybrid rhododendron, between R. nudiflorum and R. ponticum (!) was formed accidentally in a London nursery. Deliberate hybridisation began in England in 1910 when Michael Waterer made both double and triple crosses, but it was not until the 1920's that serious hybridisation began, with many nurserymen and others contributing [The Rhododendron Handbook
Part 1 (Species) and Part e (Hybrids), The Royal Horticultural Society, 1956]. A new edition, The Royal Horticultural Society's Rhododendron Handbook, was published in 1998. The clear leaders in hybridisation, were, from 1928 to 1950, Lord Aberconway at Bodnant and, from 1925 to 1954, Lionel de Rothschild at Exbury.
Rothschild bought Exbury House, which overlooks the Beaulieu estuary close to its junction with the Solent, in 1919, and began hybridising shortly thereafter. At the peak of his activities, he had some 250 acres devoted to rhododendrons.
In 1927, Lionel de Rothschild founded, and became president of, The Rhododendron Association. It was wound up in 1952, but was overtaken whilst still extant by a major publication of the Royal Horticultural Society, the Rhododendron Yearbook, first published in 1946, which evolved in 1952 into the Rhododendron and Camellia Yearbook, which lasted until 1970, and was then superseded 1972 by the present Rhododendron, Camellia and Magnolia Yearbook. 1971 was a fallow year. The author has the well-illustrated and very informative 2000, 2001 and 2002 issues, and recommends the series to those with an interest in these genera. The 2000 issue contains an article by E G Millais (see below) on the propagation of rhododendrons.
In 1934, Lionel de Rothschild asked Koichiro Wada, a nurseryman in Numazushi, Japan, for plants of unusual character and high quality. Amongst those which Rothschild received was R.yakushimanum. In England it thrives in full sun, notwithstanding its origin on Yakushima Island which is drenched with mist and fiercely windswept! (Cox and Cox, vide supra). See also: The Rothschild Rhododendrons by C E L Phillips and P N Barber, Cassell, London, 1979, who claim that one of the Rothschild's earliest introductions was the pinkish red 'J G Millais'. However, van Gelderen and van Hoey Smith (vide supra) state that 'J G Millais' ('Ascot Brilliant' x 'Pink Pearl') was introduced by J.Waterer in 1915. This is just one of such confusions in the field!
Nowadays, Exbury is open to the public, and in addition to the garden (Head Gardener Rachel Martin) has a 12 1/4 inch gauge steam railway, a gift shop and catering facilities (www.exbury.co.uk). Nevertheless, the nursery, now owned jointly by N de Rothschild and D Alexander, is still active (www.exbury-rhododendrons.co.uk): in the April 2000 rhododendron competition, Exbury entered
48 of the 58 classes, winning 28 first prizes and 24 second and third prizes. At a recent Chelsea Show, Exbury exhibited the rhododendrons 'Red Walloper' and 'Pink Walloper', both with hugh trusses of flowers. 'Pink Walloper' (syn. Lem's Monarch) won a First Class Exhibition Certificate.
Some time before 1938, Caton Haigh at Portmeirion introduced the red-flowered 'Gwyllt King' which grows in the woodlands alongside hybrids of the aforementioned R. arboreum and hundreds of others, both large and small. The woodland at Portmeirion extends to 70 acres.
R. yakushimanum, propagated in the USA by cell culture, is often considered to be the perfect rhododendron, with excellent foliage and apple-blossom pink buds opening to white. It is one component of hundreds of modem hybrids, produced during the last 20 years or so. Many of these have been made by Hans Hachman in Germany (Rhododendrons with Camellias and Magnolias, The Royal Horticultural Society, 2002, p.47). In addition to doing well in sunshine, the 'yak' hybrids are generally hardy, and produce excellent flowers. They are often easily recognised by their overall appearance, and by their indumentum, a woolly or hairy, sometimes powdery, formation on the leaves and stems. 'Dusty Miller' (yakushimanum x un-named x) has white powdery indumentum and shrimp pink flowers which fade to white; and 'Teddy Bear' (yakushimanum x bureavii), has dark green heavily veined leaves which have deep orange-brown indumentum (teddy bear colour!) on their undersides. Again, it flowers pink, fading to white. Many other 'yak' hybrids are available, with flower colours ranging from white through orange to deep red. Overall, 'yaks' are superb rhododendrons, and many of them are particularly suitable for small gardens.
A variety of rhododendrons can be obtained from local nurseries, but their stock represents a mere fraction of that available from specialist nurseries. The surnames of some of the founders of the have already appeared in the text. Details of noteworthy nurseries follow.
Knapp Hill Nursery (www.knaphillrhododendrons.co.uk), in Woking, Surrey, is one of the oldest nurseries in England. It was founded, possibly in the 1790's, by Michael Waterer. In 1852, the nursery grew many standard rhododendrons, some being 10-12 feet high, with stems 5-6 feet long and 6 inch diameter, carrying heads of about 6 feet diameter, covered in flowers! In the 1860's the nursery occupied some 350 acres, and employed 84 men, 20 boys and 3 women. Around this time, most of the stock was imported from America, and increased from seed. Many fine hybrid rhododendrons (and azaleas) were produced. During 1894 the nursery sold over 13,000 rhododendrons. Knapp Hill was sold, in 1976, by Donald Waterer to Slocock Nurseries. The current Knapp Hill-Slocock catalogue contains some 150 rhododendrons and some 100 azaleas, listed separately. Its rhododendrons won the Rothschild Challenge Cup in 1997, 1999 and 2001 for exhibits at Royal Horticultural Society rhododendron shows, and it has won 28 Gold Medals at Chelsea Flower Shows. Knapp Hill-Exbury hybrids have particularly large trumpet shaped flowers, sometimes scented.
Loder Plants, previously known as Leonardslee Plants (www.loderplants.co.uk or www. rhododendrons.com), in Horsham, West Sussex, was founded by the Loder family in 1850. In 1901, Sir Edmund Loder crossed R. griffithianum with the sweetly scented R. fortunei to give R. loderi, which in open woodland grows into a large plant, sometimes reaching 25 feet high and 80 feet in circumference, clothed to the ground with white to shell pink flowers in May. It is still considered be one of the best large-flowered varieties, and many crosses have been made from it. Loder's 2013 catalogue lists some 2500 rhododendrons and 1000 azaleas.
Hydon Nurseries, in Godalming, Surrey, was founded by A F George in 1959, he is now assisted by his wife. Their July 2002 catalogue lists over 400 rhododendrons and some 120 azaleas, with 21 colour photographs of choice specimens, including one of a Chelsea show display which won a Gold Medal.
Millais Nursery (www.rhododendrons.co.uk in Farnham, Surrey, was founded by E C Millais in 1969, Ted's interest being kindled by his Uncle, J G Millais who previously identified and described many rhododendrons for the first time; his work was published under the title Rhododendrons in two volumes, 1917 and 1924. Ted and Rorny's son now manages the nursery.
Millais' 2002-2003 catalogue contained, for the first time, colour pictures of rhododendrons in flower, some 37 in all. That catalogue listed some 440 rhododendrons and 120 azaleas. Most of the rhododendrons are grown on their own roots to produce a natural habit; some are grafted on 'Cunningham's White'.
The preponderance of rhododendron and azalea nurseries in the Surrey/Sussex area is notable. Much of the history of these and several other nurseries in this region, from 1703 to the early 1980's, is described in A: Nurserymen to the World, extensively researched by E J Willson, Dotesios Printers Ltd, Bradford on Avon. Interestingly, the redoubtable Graham Stuart Thomas prompted the writing of this book, and provided information for it.
Penton Mill (www.pentonmill.com), is a newly established rhododendron nursery, located off the A7 north of Carlisle, through Longtown and just before the Dumfries border. It is run by Alan Clark and Mandy Cullen, both of whom have made many visits to China to collect wild rhododendrons and rhododendron seed. The nursery already contains stock with flowers ranging in colour from white through pink, red, yellow and blue, in a variety of shades. Interestingly, Alan Clark was curator of the
garden at Muncaster Castle until 2000, when he left to start the Penton nursery; he is an expert on rhododendrons (see Cumbria Life, June 2002, p.74).
Glendoick Gardens (www.glendoick.com) belong to the Cox family. In 1919 Euan Cox accompanied Reginald Farrar in plant hunting in upper Burma. Cox returned early, and Farrar later died whilst still in Burma. Eventually, Cox published the book Farrar's Last Journey. Euan began to developed the garden at Glendoick in 1921, and in 1953 was joined by his son Peter (later V.M.H.); together they founded the rhododendron nursery. Peter's son Kenneth then joined in, and is now managing director. Kenneth has a young son, Jamie .... Peter and Kenneth, together and with colleagues, have extensive experience of plant hunting, and have introduced many new plant species, including a range of rhododendrons.
The Glendoick 2013 Spring Catalogue lists some 110 dwarf and low-growing rhododendrons, about 210 larger growing species and some 114 larger hybrids. There are also azaleas, and several vireyas rhododendrons which are sometimes scented and which require conditions rarely available out of doors, but which can be grown in well ventilated conservatories (for examples, see 'The Sweet Smell of Success' by Roy Lancaster, The Garden, 2002 ,127, 28). The Glendoick catalogue contains colour photographs of choice rhododendrons and azaleas.
The Coxs' knowledge of rhododendrons is extensive, and borne out by their numerous books. That on Species has been noted above; that on Hybrids was published in 1988. There are several others, including The Smaller Rhododendrons, by Peter A Cox, Batsford, London, 1985, reprinted 1990 which is a very useful guide to choosing plants for small gardens. Also, Rhododendrons and Azaleas, a Hamlyn Care Manual, by Kenneth Cox, Octopus Publishing Group, London 1998 paperback edition 2001. This excellent book, of a mere 128 pages, covers the growing of rhododendrons from preparation of the site through purchasing the plants to their aftercare. The illustrations are complementary. An older book, Rhododendrons, by F Street, Cassell, London, 1965, covers similar ground. Peter Cox and Peter Hutchinson have produced an extensively illustrated book 'Seeds of Adventure' describing plant hunting expeditions which they, with Kenneth and others, have made since 1961.