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Written by Mary P., Rutgers Master Gardener of Somerset County
Ilex verticillata, commonly known as winterberry, is a deciduous, clumping, multi- stemmed holly native to eastern North America. It is noted for its berries, has an upright-rounded shape and usually grows 6 – 12’ tall and wide. It is adaptable to light and heavy soils but prefers moist acidic soil. It grows in both sun and part sun, but produces more berries if grown in full sun.
Its stems are thin, smooth, olive-brown to purplish-brown and have conspicuous lenticels (raised pores that allow gas exchange between the atmosphere and internal cells). The leaves are simple, alternate, serrated, green, oblong 1.5 – 4” long and wide, pubescent (with fine, short hairs) on the veins beneath. The leaves turn black at the first frost.
The flowers are inconspicuous, greenish-white and appear in the leaf axils in late spring. The shrub is dioecious (separate male and female plants). To produce fruit, flowers on a female shrub need to be pollinated by a male shrub of the same species that blooms at the same time as the female shrub. Usually one male winterberry is sufficient to pollinate six to ten female plants.
Pollinated flowers give way in late summer to a crop of bright red berries, 1⁄4” in diameter. The berries are showy, add considerable impact and interest to the winter landscape and will often persist into spring.
This plant has no serious insect or disease problems, however leaf spot and mildew occasionally occur late in the season. Neutral to alkaline soil may cause chlorosis (yellowing of leaves) and even death. Fruit may abort if planted in dry soil.
There are many cultivars of this plant varying in height from 4 -10’ and in the color of the berries. A listing of these cultivars and their appropriate male pollinator can be found at the University of Connecticut
Resources:
UConn Plant Database
Lady Bird Johnson Wildflower Center
Missouri Botanical Garden
North Carolina Extension Gardener Plant Toolbox