Rhododendron Cultivars G

'G. A. Sims'

Flowers 14 to 16 in a compact truss. Corolla funnel-campanulate, 23⁄4 in. wide, blood-red with a flare of black spots. Rather spreading and straggling habit. Late May or early June. (Waterer, Knap Hill. A.M.T. 1972.) The flowers are darker than in ‘Doncaster’, also raised at Knap Hill.

'Galactic'

Flowers up to 22 in a dense truss on stout pedicels up to 1 3⁄4 in. long. Corolla campanulate, 3 1⁄2 in. wide, pale primrose, darkening in the tube, with crimson pencilling at the base. Stigma greenish yellow. Leaves up to 9 by 3 1⁄2 in., oblanceolate, clad beneath with a plastered indumentum. Tall. March-April. A fine hybrid raised by Lionel de Rothschild at Exbury from Avalanche × R. lacteum. See Rothschild Rhododendrons, pl. 35. A.M. 1964, F.C.C. 1970.

Rhododendron 'Galactic' at the Savill Garden, Windsor Great Park, UK. 20 April 2018. Image John Anderson.

Rhododendron 'Galactic' at Exbury, Hampshire, UK. 13 April 2008. Image John Anderson.

Rhododendron 'Galactic' at Exbury, Hampshire, UK. 4 April 2011. Image John Anderson.

'Galloper Light'

Flowers about twelve in a rather loose truss, on glandular-downy pedicels. Corolla 2 in. wide, funnel-shaped, strawberry pink on a cream base, with a yellow flare in the upper part, the pink coloration fading as the flower ages. Leaves semi-deciduous, rugose, dark green. A hardy vigorous hybrid of unknown parentage, growing to 6 ft high. Late May or early June. It received an Award of Merit when shown by Lionel de Rothschild in 1927 but was raised at the Knap Hill Nursery, not at Exbury.

Gaul (elliottii × Shilsonii)

Flowers about 20 in a compact truss. Corolla 2 in. wide, tubular-funnel-shaped, deep red, with a cup-shaped calyx of the same colour. (Rothschild. A.M. April 18, 1939.) A fine red, not suitable for cold gardens.

Rhododendron 'Gaul' at Exbury, Hampshire, UK. 9 May 2013. Image John Anderson.

'Gauntlettii'

This hybrid was raised by V. N. Gauntlett and Co. of Redruth, Cornwall, at the end of the last century and continued to be sold by them under this name after they moved to Chiddingfold, Surrey, in 1905–6. In their catalogue 101, which appeared early in the 1930s, they give ‘White Pearl’ as a synonym of ‘Gauntlettii’, thus implying that Messrs Cutbush had renamed their hybrid and obtained an Award of Merit for it (see ‘White Pearl’). However, they probably obtained this misinformation directly or indirectly from Millais’ work on rhododendrons, in which he asserted that ‘Gauntlettii’ and ‘White Pearl’ were one and the same, when in fact there is little doubt that the latter was simply the trade-name given to ‘Halopeanum’, raised in France.

No authentic plant of ‘Gauntlettii’ has been seen, but judging from the photograph reproduced in Messrs Gauntlett’s catalogue the corollas appear to be nearer to funnel-shaped than to campanulate, thus differing from ‘White Pearl’.

Rhododendron 'Gauntlettii' in the Savill Garden, Windsor Great Park, UK. 18 May 2021. Image John Anderson.

Rhododendron 'Gauntlettii' in the Savill Garden, Windsor Great Park, UK (1999–11993). 16 May 2023.

'Gemmiferum'

Flowers in a dense truss 3 in. across, on sticky, downy pedicels. Corolla funnel-shaped, 11⁄4 in. long and wide, of a more or less uniform purplish rose. Calyx-lobes 1⁄8 in. long, linear, hairy on the margins. Leaves 2 to 31⁄2 in. long, 1 to 11⁄2 in. wide, obovate to oval, downy beneath when young, becoming glabrous with age, dark glossy green above, pale green beneath, margins recurved. It makes an evergreen bush of rather loose habit up to 6 ft high, flowering in May or early June. Of unknown origin and parentage. Rehder suggests it might be a hybrid between the azalea R. prinophyllum (roseum) and R. catawbiense.

'Geoffroy Millais'

Flowers 14 in a tall truss; rachis 4 1⁄2 in. long. Corolla wide campanulate, 4 in. wide, lobes broad, slightly wavy, pink in the bud, opening white, with a ray of brownish-red markings, flushed with crimson on the reverse. Style pinkish with a crimson stigma, glandular in the lower half. Leaves elliptic, 6 1⁄2 by 2 1⁄8 in. One of the Schulz hybrids, raised at the Porcelain Factory, Berlin, around 1890, and distributed by van Nes. A fine white, in the same style as ‘Manglesii’ and ‘White Pearl’.

Rhododendron 'Geoffroy Millais' in the Valley Gardens, Windsor Great Park, UK. 24 April 2020. Image John Anderson.

Rhododendron 'Geoffroy Millais' in the Valley Gardens, Windsor Great Park, UK. 24 April 2020. Image John Anderson.

'George Hardy'

Flowers 12 to 14 in a conical truss; rachis 2 3⁄4 to 3 3⁄4 in. long; pedicels to 2 in. long, glandular. Calyx large, reddish, very irregularly lobed, some lobes ovate, others oblate. Corolla short-campanulate, to 3 3⁄4 in. long, lobes longer than tube, rosy in the bud, opening white with crimson markings mainly confined to the centre lobe; nectaries not coloured. Style glandular at the base. Leaves dark green, oblong-lanceolate, to 6 in. long. Medium growth. Late May. A quite handsome hybrid, standing full sun, mentioned here because it is probably a parent of ‘Pink Pearl’. It is a hybrid of R. griffithianum crossed with some hardy white, and is believed to have been raised by J. H. Mangles at Valewood, Haslemere. According to Millais, it was put into commerce by Messrs Waterer of Bagshot.

There are many hybrids of similar character to ‘George Hardy’, difficult to distinguish one from another. ‘Manglesii’ was raised by Messrs Veitch at their Coombe Wood nursery. It received an A.M. when shown by them in 1885 and was named in memory of J. H. Mangles, who had died the previous year. It is from a cross between R. griffithianum and either ‘Album Elegans’ or ‘Album Grandiflorum’. It is a more demanding plant than ‘George Hardy’, needing shade and shelter; the flowers are similar, but the style is glandular to the tip. ‘Coombe Royal’ was probably raised by Luscombe of Coombe Royal, Kings-bridge, Devon, and received an Award of Merit when shown by Messrs R. Veitch of Exeter in 1900. Plants seen under the name are very like ‘George Hardy’, but with fewer, larger flowers on a shorter rachis. Another in this group is ‘Standishii’. This is not the same as the old hybrid of that name raised by Standish and Noble from Altaclerense crossed with a hybrid between R. ponticum and R. maximum, and named in 1850. But Standish may well have experimented with R. griffithianum in the later years of his life. A plant in the Knap Hill nursery under this name differs from ‘George Hardy’ in having corollas with coloured nectaries and two lines of speckles (in ‘George Hardy’ they are all in one group).

Rhododendron George Hardy just coming into flower in the Valley Gardens, Windsor Great Park, UK. 11 May 2021. Image John Anderson.

A fully open truss on Rhododendron George Hardy in the Valley Gardens, Windsor Great Park, UK. 11 May 2021. Image John Anderson.

Rhododendron George Hardy in the Valley Gardens, Windsor Great Park, UK. 26 May 2020. Image John Anderson.

Rhododendron George Hardy at Exbury, Hampshire, UK. 12 May 2014. Image John Anderson.

Rhododendron George Hardy in the Valley Gardens, Windsor Great Park, UK. 14 May 2020. Image John Anderson.

'George Johnstone'

In 1967 the A.M. was given to the clone ‘George Johnstone’, raised at Trewithen and exhibited by Collingwood Ingram, Benenden, Kent.

see notes for Trewithen Orange group

'George Reynolds'

Deep yellow, 31⁄2 in. wide, with a flare of orange spots. Raised at Knap Hill and acquired by Lionel de Rothschild, this is a parent of the famous Exbury strain of the Knap Hill azaleas. It received an Award of Merit when shown from Exbury on May 19, 1936. Rothschild Rhododendrons, plate 47.

'Gibraltar'

Rich orange-red, frilled, in a large truss (Knap Hill-Exbury, 1947).

'Gilian'

Another fine clone of Cornish Cross is ‘Gilian’ (A.M. 1923). It was raised by E. J. P. Magor, who originally gave the parentage as R. campylocarpum × R. griffithianum but later became convinced that he must have misrecorded the cross. His son Major Walter Magor tells us his father was eventually quite satisfied that ‘Gilian’ is a form of Cornish Cross. The flowers are rich crimson red, fading at the centre as they age.

Gladys (campylocarpum × fortunei)

Flowers about 10 in a loose truss. Corolla widely funnel-shaped, 6-lobed, 3 1⁄2 in. wide, pale cream with a few purple markings. Leaves oblong-ovate, 4 in. or slightly more long, 2 in. wide. Late April or early May. This description, from the ‘Ivens Manuscript’, is of the original ‘Gladys’, which received an A.M. when shown by Lord Swaythling of Townhill Park in 1926. It was raised, according to this source, by Brig.-Gen. Clarke of Chilworth Manor, near Southampton, not by Col. S. R. Clarke of Borde Hill, as stated in Journ. R.H.S., Vol. 52, p. lii, though this cross was made at Borde Hill also. Three years before ‘Gladys’ was exhibited by Lord Swaythling, the cross was made in his garden by F. J. Rose, using R. campylocarpum “var. elatum” and a selected form of R. fortunei. The plants first flowered in 1931, and a group of trusses from them was a feature of the Rhododendron Show of that year. The colours ranged from cream to deep pink. On the same occasion an Award of Merit was given to ‘Mary Swaythling’, presumably one of this set, in which the flowers are primrose-yellow with no markings.

‘Gladys Rose’ received an A.M. when shown by the Crown Estate Commissioners in 1950. This has flowers in a lax truss of about nine; corolla ivory-yellow, darker on the upper lobe, flushed pale pink and also pink in the bud. It was raised at Townhill (see above).

The cross using R. campylocarpum “var. elatum” was also made by Messrs W. C. Slocock and the results, varying in colour, were given the grex-name Letty Edwards, the individual plants being distinguished by numbers. But the clonal name ‘Letty Edwards’ is now attached to the clone which received an F.C.C. after trial at Wisley in 1948. This has flowers in trusses of ten to twelve, corolla widely funnel-shaped, pale primrose shaded deeper on the upper lobe and in the throat, unmarked except for faint greenish-yellow speckling in the throat.

Rhododendron 'Gladys' in the Valley Gardens, Windsor Great Park, UK. 27 April 2020. Image John Anderson.

'Gladys Rose'

‘Gladys Rose’ received an A.M. when shown by the Crown Estate Commissioners in 1950. This has flowers in a lax truss of about nine; corolla ivory-yellow, darker on the upper lobe, flushed pale pink and also pink in the bud. It was raised at Townhill (see above).

'Glory of Littleworth'

Truss compact, hemispherical, with fifteen to eighteen flowers; rachis 21⁄4 in. long; pedicels 1 to 11⁄2 in. long, glandular-downy. Corolla 2 in. wide with a slender tube, fragrant, cream fading to milky white, with a large blotch of coppery orange spots. Stamens six to eight. Leaves oblong-lanceolate with impressed laterals. Late May or early June. A lovely but rather demanding plant, not often seen in good condition. It received an Award of Merit on May 23, 1911, when shown by Miss Clara Mangles of Little-worth Cross near Farnham and was almost certainly raised there by her brother Henry Mangles (d. 1908), who, like his brother James Mangles (d. 1884), was a keen hybridiser.

'Glowing Ember'

‘Glowing Ember’ is of the same parentage and from the same raiser as ‘Lava Flow’.

'Gog'

Orange-red (Knap Hill, before 1927, distributed by Messrs Slocock). An azalea of exceptional vigour, colouring well in the autumn.

Rhododendron 'Gog' in the Sir Harold Hillier Gardens, Hampshire, UK. 2 May 2012. Image John Anderson.

'Goldcrest'

Chrome-yellow with a flare of darker yellow, fragrant. Early (Knap Hill). A.M.T. May 11, 1953.

'Golden Eye'

Vermilion red with a large tangerine flare (Knap Hill). A.M.T. May 22, 1952.

Golden Horn (dichroanthum × elliottii)

Flowers about seven in the truss on glandular-downy pedicels. Calyx fleshy, enlarged, coloured like the corolla, which is campanulate, about 21⁄2 in. wide, orange in the bud, opening deep salmon-pink blending with orange and mottled with brown. Leaves oblanceolate, to 5 in. long, obtuse, dull green above, bright green on the underside beneath a thin brown indumentum. Low-growing and compact. Late May or early June. (Rothschild.) The description is of the clone ‘Golden Horn’ (A.M. 1945). In ‘Persimmon’ the corolla is deep, glowing red speckled with black dots, and the calyx is smaller (Rothschild Rhododendrons, pl. 11).

'Golden Orfe'

(concatenans × ‘Lady Chamberlain’)

Flowers about seven in the truss. Corolla similar to that of R. concatenans in shape, i.e., tubular-campanulate and rather short, 2 in. long and wide, orange-yellow (Nasturtium Orange, 25c). Raised at Tower Court, Ascot, and taken to Tremeer, Cornwall, by Mrs Stevenson after her remarriage to Gen. Harrison. A.M. 1964. It is in commerce.

'Golden Oriole'

Bright yellow with a darker flare, fragrant. Very vigorous and free-flowering. Early (Knap Hill).

Rhododendron Golden Oriole Group at RHS Garden Wisley, UK. 9 March 2026. Image Tom Christian.

Golden Oriole (moupinense × sulfureum)

Trusses mostly three-flowered; inner bud-scales crimson. Corolla tubular-funnel-shaped, about 2 in. wide, resembling that of R. sulfureum but of a beautiful shade of clear light yellow (Dresden Yellow). Leaves elliptic, obtuse, about 2 in. long. Stems cinnamon-brown, peeling. A small shrub of erect habit. March. (J. C. Williams.) This description is of the clone ‘Golden Oriole Talavera’ (F.C.C. 1963), for which a white-flowered R. moupinense was used (R.C.Y.B. 1964, pl. 3). ‘Golden Oriole Busaco’, from a pink-flowered form of that species, has the corollas primrose-yellow suffused with pale pink, with some crimson spots on the upper lobes. Both are lovely and probably hardy, but flower too early for most gardens.

Rhododendron 'Golden Oriole' in the Savill Garden, Windsor Great Park, UK. 17 March 2014. Image John Anderson.

'Golden Sunset'

Light yellow tinged with orange-red in the bud and when first expanded; flare orange (Knap Hill-Exbury, distributed by Waterer, Bagshot). A.M. May 22, 1956.

'Goldfort'

Flowers about 12 in the truss. Corolla funnel-shaped, 3 in. wide, 5– to 7-lobed, pink in the bud, opening pale primrose tinged with apricot, speckled with green in the throat. Style glandular in the lower half, with a greenish stigma. Late April or early May. (fortunei × ‘Goldsworth Yellow’; Slocock.)

'Goldsworth Crimson'

Flowers 12 to 16 in a compact truss. Corolla funnel-shaped, 31⁄2 in. wide, lobes broadly rounded at the apex, bright red, fading towards the centre and darker on the reverse, upper lobe speckled with black. Medium size, of fairly compact, spreading habit. Early May. (‘Doncaster’ × griffithianum hybrid; Slocock. F.C.C.T. 1971.)

'Goldsworth Orange'

Flowers in a lax truss of up to ten; pedicels bright green. Corolla funnel-shaped with a broad base, 6– or 7-lobed, fleshy, yellow, lobes paler than tube and tinged with pink, upper part of throat with a broad band of greenish-brown speckles. Low, spreading habit. June (dichroanthum × discolor; Slocock. A.M. 1959.)

'Goldsworth Yellow'

Flowers up to 16 in the truss on ascending pedicels Corolla funnel-campanulate, 2 1⁄2 in. wide, undulated at the margin, lobes at first angled owing to infolding at the tips, buff-pink in the bud becoming pale creamy yellow but pink-tinged at first, especially on the ridges outside, speckled brown in the upper part of the throat. Leaves medium green, reticulate above, mostly oblong-obovate, to 5 in. long. Moderate height, spreading habit. End April or early May. A.M. 1925, when shown by Messrs W. C. Slocock. Millais published the name ‘Goldsworth Yellow’ in the first volume of his Rhododendrons (1917), p. 38, and gives the history of the plant in his second volume, p. 103. According to his version, the original was bought in the winding-up sale of Veitch’s Coombe Wood nursery (1913–14). But he also records that Messrs Slocock made the cross R. caucasicum stramineum × R. campylocarpum before 1917, and this is a likely parentage for ‘Goldsworth Yellow’.

Although many yellow-flowered hardy hybrids have been raised since, ‘Goldsworth Yellow’ remains one of the most useful, as it stands full sun and does not flower unduly early.

Rhododendron 'Goldsworth Yellow' in the Valley Gardens, Windsor Great Park, UK. 26 May 2020. Image John Anderson.

'Gomer Waterer'

Flowers about 20 in a handsome rounded truss. Corolla wide funnel-shaped, 3 in. wide, mauve in the bud, opening white flushed with mauvish pink at the edges, with a flare of yellowish brown on the upper lobes. Leaves dark green, very leathery, elliptic or slightly obovate, to 5 in. long. Moderate, dense growth. Early June. (Waterer, Bagshot. A.M. 1906.) A tough, wind-resistant rhododendron, but with beautiful flowers.

Close-up on a truss of Rhododendron 'Gomer Waterer' near the Savill Garden, Windsor Great Park, UK. 19 May 2020. Image John Anderson.

Close-up on a truss of Rhododendron 'Gomer Waterer' near the Savill Garden, Windsor Great Park, UK. 19 May 2020. Image John Anderson.

'Govenianum'

Also in cultivation is ‘Govenianum’, which may represent a single clone. It resembles the plant described in most respects, including the glaucous undersurface of the leaf, but the flowers are of a darker shade, and the calyx-lobes narrower and more strap-shaped. The hybrid described by Sweet in 1828 under the name R. Gowenianum was raised by Gowen at Highclere from either R. viscosum or R periclymenoides pollinated by a hybrid of R. ponticum and R. catawbiense (Brit. Fl. Gard., t. 263 (1828)). But it is possible that the plant now cultivated is the result of some unrecorded cross made by Gowen, similar to that made by the Rev. William Herbert, who was the brother of the second Earl of Carnarvon, the owner of Highclere and patron of Gowen.

Gowen also made a cross at Highclere in 1825 between R. periclymenoides and R. catawbiense (pollen-parent), from which 97 plants were raised; the best was named ‘Carton’s Rhododendron’ by Lindley, after the head gardener there (Bot. Reg., t. 1449 (1831)). This was given botanical status by de Candolle as R. cartonianum (syn. R. cartoni Bean).

'Graciosa'

Soft yellow at first, becoming white, tinged with pink at the edge; large orange flare (Occidentale Hybrid; M. Koster and Sons). A.M. 1908.

'Grand Arab' ('The Grand Arab')

Flowers 15 in a compact, conical truss; rachis 1 in. long. Corolla funnel-shaped, 2 in. wide, magenta-crimson with slight black spotting at the base of the centre lobe. Style crimson, glabrous. Ovary densely white-felted. Calyx with shallowly triangular, glandular-ciliate lobes. Leaves narrowly elliptic, tapered at both ends, 4 by 13⁄4 in., clad beneath with a scarcely visible indumentum. It makes a well-shaped bush to 10 ft or slightly more high. Early May. An old hybrid of R. arboreum. Nothing is known of its origin, but it was listed by John Waterer in 1854. In the following year he put into commerce the much later flowering ‘John Waterer’ and ‘Mrs John Waterer’, but ‘Grand Arab’ has persisted in cultivation, especially in the North and Midlands.

Grenadier (elliottii × 'Moser's Maroon')

Flowers about 12 in a globular truss; rachis about 1 1⁄2 in. long. Corolla funnel-campanulate, of waxy texture, 3 to 3 1⁄2 in. wide, deep red, with dark nectar-pouches and some dark speckling on the upper lobes. Leaves dark green, elliptic, with a loose tomentum beneath. Tall and vigorous. June. This is one of the finest hybrids raised by Lionel de Rothschild from R. elliottii, but in common with other late-flowering hybrids of the Parishii group it is slow to ripen its growths, which may be damaged by autumn frosts. It received a First Class Certificate in 1943.

Rhododendron 'Grenadier' in the Savill Garden, Windsor Great Park, UK. 19 April 2017. Image John Anderson.

Close-up on Rhododendron 'Grenadier' in the Savill Garden, Windsor Great Park, UK. 19 April 2017. Image John Anderson.

Grievei

The hybrid Grievei is usually supposed to be of the same parentage as ‘Rosy Bell’, but the International Register gives it as ciliatum × virgatum, i.e., the same as Multiflorum. It was raised by James Grieve (d. 1924), who also bred the well-known apple named after him. He set up his own nursery at Pilrig in 1896, but apparently raised this hybrid earlier, while working for Messrs Dickson and Sons of Edinburgh.

'Grilse'

Clones of Jalisco have been crossed at Windsor with Fusilier and two of the resulting hybrids have received awards: ‘Grilse’, A.M. May 20, 1957, R.C.Y.B. 1958, p. 109

Grosclaude (eriogynum × haematodes)

Flowers up to 10 in a lax truss on stellate-hairy pedicels. Calyx irregular, large, coloured like the corolla, which is campanulate, 21⁄2 in. wide, fleshy and glossy, deep scarlet-red, with some black speckling. Leaves to 41⁄2 in. long, rounded at the apex, dull green, coated beneath with a brown indumentum. Compact and fairly dwarf. June. (Rothschild. A.M. 1945.) It flowers later than the May Day grex, from which it differs in the shape of the corolla and other characters.

Gumpo

The so-called Gumpo azaleas are usually listed under R. simsii var. eriocarpum (Hayata) Wils. (for which see under R. indicum). Whatever may be the status of the wild plants placed under this variety, the Gumpo azaleas, which came from a Japanese nursery, are near to R. indicum and are best treated as a horticultural group of uncertain taxonomic position. All are of low, spreading habit, building up to 2 ft or slightly more in height, and mostly differ from typical R. indicum in their darker, blunter leaves. In common with that species they flower late, in early June.

All the Gumpo azaleas are said to be rather tender.

'Gumpo Fancy'

Another member of the Gumpo group, has Mallow Purple flowers, speckled on the upper lobe.

'Gumpo Red'

‘Gumpo Red’, as seen in British gardens, has flesh-pink flowers with darker staining on the upper lobe, not ‘salmon rose’ as stated in the catalogue of Mr Wada, who distributed these Gumpo azaleas from his Hakoneya Nursery before the second world war. It is possible that this pale pink form is the result of propagating a branch-sport of the original ‘Gumpo Red’, since a plant has been seen on which one twig bore flowers agreeing with Wada’s description. The corollas in ‘Gumpo Red’, as seen, are waved and frilled, about 21⁄4 in. wide; stamens five, with dark anthers.

'Gumpo White'

In ‘Gumpo White’ the corolla is pure white, frilled, about 2 in wide; stamens five, with brown anthers.