870 Ilex verticillataCommon Names: common winterberry, black alder, coralberry, Michigan holly Family: Aquifoliaceae (holly Family)
Common winterberry is a deciduous holly. This is a large shrub or small tree that can get 25 ft (7.6 m) tall, but is usually considerably smaller. In cultivation winterberry usually grows as a 6-12 ft (1.8-3.7 shrub. The trunk is short and generally branches close to the ground, and the stout, erect to spreading branches bear slender twiggy branchlets, producing a rounded crown, 8-12 ft (2.4-3.7 m) across. Common winterberry often suckers and grows in a multistemmed clump, and may form a thicket of erect stems. The leaves are variable in size, sometimes even on a single branch, ranging from 1-4 in (2.5-10.2 cm) long and half as wide. They are toothed along the margins and the apices are usually acuminate, which is to say the leaf tips taper to a point and the sides of the taper are concave. Usually the leaves are smooth above and hairy beneath.
Like many hollies, winterberry is dioecious, with male and female flowers on separate plants. The tiny flowers have four white petals. The fruits are globose red berrylike drupes, about 0.25 in (0.6 cm) in diameter. They usually persist after leaf fall in the autumn, hence the common name. There are a great many cultivars of this popular landscape shrub. 'Winter Red' is perhaps the most popular, and deservedly so. It is a bushy shrub with multiple stems that bear a profusion of large bright red fruits which persist through the winter longer than other selections. 'Nana' (a.k.a. 'Red Sprite') is a dwarf cultivar which bears large berries, but gets only 2-4 ft (0.6-1.2 m) tall. There are forms with yellow and orange fruits which occur occasionally in nature and may be available from native plant nurseries. Ilex verticillata has been hybridized with other deciduous hollies (especially I. serrata, Japanese winterberry), and several selections of these are available to gardeners.
Common winterberry, Ilex verticillata, grows in swamps and wet woods from Nova Scotia and Quebec, west to Minnesota and thence south to Arkansas and the Florida Panhandle.
CultureCommon winterberry does best in moist, slightly acidic soils with a high organic component. Leaves will yellow in neutral soils and the plant will likely die in alkaline soils. Most hollies are rather slow growing plants and winterberry is no exception. To insure good pollination, and hence a good fruit set, you need at least one male plant for every 10-20 female plants. The pollinator plants can be up to 50 ft (15.2 m) away and placed in the background. Dwarf male clones are available for pollination. Common winterberry flowers on new growth, so any pruning can be done in late winter before the new growth begins. Light: Full sun to partial shade. Winterberry flowers and fruits better in full sun. Moisture: Common winterberry is not at all tolerant of drought. It performs well in poorly drained soils. Water regularly. Hardiness: USDA Zones 3 - 9. The deciduous hollies are, as a rule, more cold hardy than their evergreen cousins. Propagation: The cultivars of common winterberry are propagated from softwood cuttings taken in summer and rooted under glass with mist.
Common winterberry is a great shrub for wet areas in the landscape. Use it in shrub borders or in masses for its winter berry display. Winterberry is a good choice for an unclipped hedge. It looks great in front of evergreens. The cultivar,'Winter Red' is frequently used in highway plantings.
Winterberry branches with their showy red berries are used for Christmas decorations, and there is a commercial industry cultivating the plants for that purpose. 'Oosterwijk' is a cultivar named in the Netherlands and grown there for the branches which are exported around Christmas time. Use them dry (don't put in water) and they will keep for months indoors. Many kinds of birds eat the fruits and often the shrubs are stripped bare before Christmas.
Common winterberry, loaded with bright red berries on slender twigs is one of the prettiest shrubs in winter. It's especially attractive standing proudly with snow on its branches. If the leaves haven't fallen by the first hard frost, they turn black, hence the common name, "black alder." Don't try to grow this shrub if your soils are neutral to alkaline. Instead, choose possumhaw (Ilex decidua), another American native which is better adapted to such soils.
Of the 400 species of hollies in the world, only about 30 are deciduous.
Steve Christman 11/24/00; updated 11/16/03, 3/23/05