Culture
Easily grown in average, medium moisture, acidic, well-drained soils in full sun to part shade. Best in locations protected from cold winter winds. Part afternoon shade best in hot summer climates. Avoid poorly drained soils. Prune in winter if needed. Hollies are dioecious (separate male and female plants). ‘Rock Garden’ is a female clone that requires a male holly pollinator for fruit production. May not be reliably winter hardy throughout USDA Zone 5 where it should be sited in a sheltered location and given winter protection.
Noteworthy Characteristics
Ilex is a genus of over 400 species of evergreen and deciduous trees, shrubs and climbers from tropical, subtropical and temperate regions. Many are grown for their attractive, evergreen foliage.
Genus name comes from the Latin name Quercus ilex for holm oak in reference to the foliage similarities (holm oak and many of the shrubs in the genus Ilex have evergreen leaves).
‘Rock Garden’ is a dwarf, spreading, hybrid evergreen holly that typically grows to only 12” tall by 22” wide over 15 years. This is a dense, diminutive shrub that features spiny-toothed, elliptical, glossy deep green leaves (to 1.5” long). Greenish-white flowers appear in May and are generally inconspicuous. Pollinated flowers give way to small red berries, which ripen in fall and persist throughout the winter. Even with good pollination, however, fruiting can be rather sparse for this cultivar. Birds are attracted to the fruit.
Problems
Potential insect problems include holly leaf miner, spider mites, whitefly and scale. Potential disease problems include leaf spot, leaf rot, tar spot and powdery mildew. Plants are also susceptible to leaf drop, leaf scorch and chlorosis (yellowing of leaves in high pH soils).
Uses
Dwarf holly for rock gardens, border fronts and foundations. A small plant for a small space. Foliage and fruit provide good color for the winter landscape. Also may be grown in containers.