Rhododendrons - Exbury Hybrids
European species have been in cultivation since 16th century. The first introduction to Britain from Europe was the Alpine R. hirsutum in 1656, followed by R. ponticum, R. ferruginium, R. caucasium. From the seventeenth century American species appeared, such as R.maximum and R. catawbiense.
Hybrids made between these early species are known as hardy hybrids.
The major breakthrough in hybrid breeding began in the 1850’s following the arrival of 43 new species, introduced by Joseph Hooker, from his Sikkim Himalaya expedition of 1847 to 1851. His collection included such gems as; R. barbatum, R. arboreum, R. thomsonii, R. campylocarpum, R. niveum, R. falconeri.
Also significant was Robert Fortune’s introduction from East China in 1856 of the strongly scented, R. fortunei. These introductions were joined by many more from further expeditions at the beginning of the twentieth century.
Intrepid characters such as George Forest, Frank Kingdon-Ward, Joseph Rock and Reginald Farrer risked all to bring back horticultural gems. Forest and Kingdon-Ward were the most prolific collectors, they sent back thousands of packets of seeds from species already known and also discovered new species.
These new Rhododendron species and good selections of known species flooded into gardens, with them a glorious new palette of colours, heavenly scents and graceful flower forms. No wonder Rhododendron Fever took a grip of men like Lionel de Rothschild.
Lionel de Rothschild chose to purchase Exbury in 1919, primarily because of its suitability for growing Rhododendrons. It is inland enough to be sheltered from salt laden winds, has a light free draining, acidic soil and existing woodland canopy providing much needed shade.
The only draw back was the low summer rainfall but he overcame that by sinking two bore holes, building a water tower and laying 22 miles of irrigation pipes.
The Rothschild family do not believe that he worked to a grand plan but rather that the garden developed organically. However, he did have strong ideas and rules to which he adhered.
He was proud to be one of the first ‘woodland gardeners’ and he strongly believed what had been done in herbaceous borders by the likes of Gertrude Jekyll could just as well be done on a large scale in the woodland with azaleas and rhododendrons.
He believed in enhancing nature with colours but had strict guide lines regarding colour combinations.
He said, ‘avoid purple with red or pink, sealing wax red must not be near crimson, orange/salmon only with white, magenta with pure colours.’
If plants were found to be in the wrong spot he would ‘take them for walks’ until the right spot was found.
In the early years before he started producing his own hybrids he had several rich sources of supply. He shopped at the famous nurseries of Surrey, West Country Nurseries and exchanged with fellow enthusiasts.
In Surrey, nurseries such as Waterer’s and Standish and Noble, specialised in Hardy Hybrids.
The West Country had been favoured in the distribution of Hooker’s seedlings as many were slightly tender. One of the most famous nurseries in Cornwall was that of Richard Gill at Tremough. He raised spectacular hybrids using Hooker's and Fortune’s introductions. Lionel certainly purchased R. ‘Werei’, a hybrid between R. arboreum and R. barbatum. His original specimens towers to 30ft in the Home Wood.
From his many, fellow gentleman enthusiasts he received several plants. JC Williams of Carhays Castle, Cornwall gave him R. ‘Moonstone’, a beautiful hybrid between R. campylocarpum and R. williamsianum.
From Lord Aberconway of Bodnant came R. ‘Cilipense’. It’s name gives away the two parents, R. ciliatum and R. moupinense. He kept meticulous records. His stud book lists his crosses, each one prefixed LR. Out of 1210 listed crosses 462 have been named.
Every seedling from every cross was grown to flowering stage and ruthlessly burnt if thought inferior. Showing the hybrids became a preoccupation, he received awards from the RHS for an incredible 238 Rhododendron species and hybrids.
He bred either using a favourite species, for pure colour, for unusual colour or for extreme early or late flowering.
A further significant introduction was made in 1932, through Exbury Gardens, of the Japanese species Rhododendron yakushimanum. This has been widely used to produce compact modern hybrids, suitable for smaller gardens.