Culture
Easily grown in average, medium moisture well-drained soils in full sun to part shade. Tolerant of a wide variety of soils ranging from moist to dry and from sand to clay. Prefers light, moist, acidic soils with good drainage. Established plants have some tolerance for drought. Plants may struggle with the heat and humidity of summers in the deep South in USDA Zones 8-9. Plants are dioecious (male and female flowers on separate plants), so both male and female plants must be present in order for the female plant to be pollinated and produce fruit.
Noteworthy Characteristics
Ilex crenata, commonly known as Japanese holly or box-leaved holly, is a dense, multi-branched, evergreen shrub with a rounded form that typically matures to 5-10’ tall and as wide. It is native to forests, thickets and mountain slopes in Japan, Korea, China and eastern Russia (Sakhalin). It is noted for its ovate to elliptic, crenate to serrulate, glossy, spineless, evergreen, deep green leaves (to 1 1/4" long) which are attractive all year, 4 petaled white flowers which bloom in 3-7 flowered cymes in late spring (May-June), and black rounded somewhat inconspicuous fruits (drupes to 1/4” diameter) which mature in fall on pollinated female plants.
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).
Specific epithet is in obvious reference to the crenate margins of the leaves.
'Helleri' is a dwarf-rounded, slow-growing, evergreen, female cultivar that is densely clad with tiny, glossy, obovate, evergreen leaves (to only 1/2" long). It typically matures to 2-4' tall and to 3-5' wide over time unless pruned smaller. It infrequently produces spring flowers or fall fruit. 'Helleri' was introduced into commerce in 1936 by J. Helleri of Newport, Rhode Island.
Problems
No serious insect or disease problems. Spider mites can be troublesome. Nematodes are a problem in the South.
Uses
Mass or group. Hedge. Borders. Incorporate into a foundation planting.