Ilex crenata 'GOLDEN ROCK'® Japanese holly, box-leaved holly
Ilex
The genus Ilex, commonly known as holly, is very extensive and includes more than 400 species of evergreen and deciduous shrubs and trees, distributed from the tropics of South America through the subtropics of Asia to the temperate zones of Europe. In addition to the possibility of variegated foliage, their greatest advantage is evergreen character, at least in most species, which makes them an excellent complement to deciduous trees and shrubs during the dormant season. Moreover, many hollies naturally lack spines, which will please those who dislike prickly shrubs. The most horticulturally significant are the East Asian species, among which the Japanese holly (Ilex crenata) stands out. This species was described in 1784 by the Swedish botanist Carl Peter Thunberg (1743–1828) during his stay in Japan.
Japanese hollies are very useful and elegant evergreen shrubs that many people at first glance mistake for boxwoods or honeysuckles because of their small, glossy leaves. This very resemblance has predestined them to become the ideal replacement for true boxwoods, which in Europe are gradually disappearing under the pressure of the massive invasion of the box tree moth and due to the fungal disease known as box blight, which has been devastating plantings especially in the British Isles. Japanese hollies, however, are thornless, offer a wide range of shapes and sizes, and require only minimal care. Since they are naturally quite variable, new mutations and cultivars often appear, each slightly different from the last – and every novelty is, of course, a welcome delight.
One of the most elegant shrubs is undoubtedly this Japanese holly. It has leaves similar to boxwood and is often used as its substitute. Golden Rock? is a recent introduction from German town Wiesmoor, where Uwe Renken found it in 2000 as a natural mutation of another holly variety called Golden Gem. The plant was patented in 2009 under PP20,062 in USA and 20070174 in Europe. Propagation without license is prohibited.
Golden Rock? is attractive for its golden-yellow top leaves, leaving the bottom ones dark green. This bicolour effect is very unusual and elegant. Leaves are gently serrated at margins. Fruits, if any, are small, glossy black berries in autumn. As opposed to its parent this plant grows upright and not as wide as Golden Gem. This can make it a nice, compact specimen with bright coloured foliage. Pruning in spring will encourage new growths, and trimming by end July is ideal for shaping.
Box-leaved holly is usually trouble-free, it does best in medium fertile, acid, moist but well-drained soil. Once established it can withstand summer dry spells. Grow it in full sun or part shade, in full shade it will lose its shape and brighntess. Hardy to min. -27°C (USDA zone 5b).
Last update 06-02-2010
