Rhododendron Cilpinense

Rhododendron ‘Cilpinense’ is a small evergreen shrub prized for its very early spring flowering, in a very pale pink touched with a deeper rose. Compact and not too bulky, it is suitable for partially shaded borders, small gardens, and pot cultivation on a sheltered terrace. The young plant is quite hardy, but its flowering can be damaged by frost; this variety will perform better under a not-too-cold oceanic climate.

‘Cilpinense’ belongs to the Ericaceae family. It is a hybrid rhododendron obtained at Bodnant Garden (Tal-y-Cafn, Wales) by Lord Aberconway, a little before 1923. Its name results from a contraction of its two parents: R. ciliatum and R. moupinense. Compared to these two species, the hybrid is more floriferous and more compact; it tolerates cold better than R. moupinense and its flowers are a little larger than those of R. ciliatum.
Rhododendron ‘Cilpinense’ is rounded and dense, and its growth is slow to moderate; at 10 years old, it reaches 0.50 m to 0.90 m in height depending on conditions, with a comparable spread. In a pot, it remains smaller. The evergreen foliage is formed of small, oval, dark green, leathery leaves. The inflorescences, in small clusters, bear campanulate flowers of a very pale pink with a darker centre. They open very early in the season, from February to April, depending on the climate (sometimes as early as January in a very mild microclimate). The hardiness of this bush is around -15 °C, but the flower buds are sensitive to late frosts. The stems are grey to brownish, the bark smooth on young wood; the root system is very shallow, requiring an aerated soil and a mulch.

Plant ‘Cilpinense’ at the edge of a light woodland, in front of taller evergreens that filter the wind. Provide it with an acidic soil (pH 4.5–6), rich in humus, moist but well-drained. In a border, place it at the front of a group of acid soil shrubs and spring bulbs or hellebores. In a pot, use a wide container, an acidic and aerated substrate, and protect the flower buds from frosts in late winter. You can pair it with spring-flowering camellias like ‘Donation’, later-flowering dwarf rhododendrons (Rhododendron impeditum 'Ramapo') or compact yakushimanum such as ‘Percy Wiseman’.

Origin of the parents: R. ciliatum comes from the mountains of eastern Nepal, Bhutan, and southern Tibet, between 2,400 and 4,000 m altitude; R. moupinense is native to western Sichuan (Moupin/Baoxing district), and is also alpine. 
Bodnant Garden, where ‘Cilpinense’ originated, remains a premier site for rhododendron hybridisation in the UK and preserves a historical varietal heritage, a testament to this period of horticultural creation.