Rhododendron edgeworthii

Rhododendron edgeworthii is a curious and magnificent Chinese species of tall stature, native to the high-altitude forests of the eastern Himalayas. It is typically found anchored in the humus-rich soil of the understory, but also, surprisingly, on decomposing stumps, similar to certain epiphytic orchids. This rhododendron definitely bewilders with one of the most fragrant flowering displays in its genus and an unusual evergreen foliage. Adorned in April-May with fragile flowers, varying in shades of pink with red reverses, and dressed year-round in wrinkled leaves covered in gray-ochre velvet, this bush is as fascinating as it is attractive in all seasons. It must be said, cultivating this less hardy species is not the easiest task and requires a specific soil and climate, but what pride for the attentive gardener who manages to tame it!

Rhododendrons belong to the Ericaceae family, just like heathers, and prefer soils that lack limestone, tend to be acidic, and thrive in wet climates. Rhododendron edgeworthii, discovered and collected by JD Hooker in Sikkim in 1849, thrives in the understory as well as on cliffs among the rocks of the Himalayas, at elevations between 2000 and 4000 m (6562 and 13123ft). It is characterised by moderate hardiness, up to -10/-12°C (14/10.4°F), significant growth, and both terrestrial and epiphytic tendencies. It is the parent of many fragrant flowering hybrids.

This beautiful bush, awarded by the Royal Horticultural Society, displays an erect, sparsely branched, conical habit, slightly taller than wide. Its growth is slow, reaching an average height of 2.5 m (8ft) with a spread of 2 m (7ft) at maturity, under favourable conditions. The yellowish branches bear elliptical to ovate, wrinkled, evergreen leaves measuring 5 to 10 cm (2 to 4in) long. Their colour is a dark green with a slightly grey and glossy upper surface, while the undersides are covered in a velvety grey-ochre or rusty down. The young shoots and flower buds are also covered in grey down. The highly fragrant flowering typically occurs in April-May, earlier or later depending on the climate. The large campanulate flowers, measuring 3.4 to 7.5 cm (1 to 3in) in diameter, are grouped in inflorescences of 2 or 3 units, with a width of 6 to 15 cm (2 to 6in). The buds are a vivid red-pink, while the flowers are white with varying shades of pink along the edges, displaying a small yellow spot at the throat. The petals' undersides are dark red. This bush thrives in mild climates, preferring partial shade and moist, humus-rich, well-drained soils with an acidic pH between 4.5 and 5.5. Some British professionals recommend growing it in an orchid substrate.

Rhododendron edgeworthii may not be the most cold-hardy, but it enchants with the beauty of its foliage and the delicacy and fragrance of its flowering, which precedes that of most other rhododendron. It can be used as a specimen, in a small hedge, or in a mass planting, of course alongside other acid-loving plants, but always in a well-drained soil. It can be paired with Chinese azaleas, complementing and tempering their warm hues, small deciduous magnolias, andromedas (Pieris), mountain laurels (Kalmia), painted ferns, Viburnum davidii, and more. Some patient gardeners train it against a sheltered wall to fully enjoy its beautiful fragrance as soon as the first warm days arrive.