General Culture: Easily grown in average, medium, well-drained soils in full sun to part shade. Tolerant of a wide range of growing conditions, including urban pollution. Prefers light, moist, acidic soils with good drainage. Chlorosis (leaf yellowing) may occur in alkaline soils. Japanese hollies are dioecious (separate male and female plants). ‘Sky Pencil’ is an all-female cultivar which needs a male pollinator in order to produce fruit. Maintains columnar shape without pruning. May not be reliably winter hardy throughout USDA Zone 5 where it should be grown in a protected location with a winter mulch.
Noteworthy Characteristics: This evergreen Japanese holly cultivar is an exceedingly narrow, fastigiate form which grows somewhat slowly in a vertical, pencil-like column to 10′ tall but only 2-3′ wide. A typical 4-6′ tall specimen may only be 10-12″ wide. ‘Sky Pencil’ is an introduction of the U.S. National Arboretum in Washington, D.C. Features elliptic to obovate, small dark green leaves (typically 1/2 to 1 1/4″ long) which have serrulate margins, particularly at the rounded tips. Japanese holly foliage somewhat resembles boxwoods more than hollies. Tiny, greenish-white flowers appear along the stems in the leaf axils in late spring. If pollinated, the flowers give way to purple, berry-like drupes (1/4″ diameter) in fall. Flowers and fruit are inconspicuous. Zones 6 to 8.