In January, the Chicago area starts to see more regular snow cover, and many of our native plants are resting beneath the protective blanket of white. Splashes of color are few and far between in the brown, gray and white landscape. Winterberry (Ilex verticillata) is in the spotlight this month, its bright red berries a welcome sight for both people and overwintering birds.
Winterberry is a member of the holly family (Aquifoliaceae) and is native to northeastern Illinois. It is seen occasionally in damp woodland edges, soggy thickets and on rocky riverbanks. It likes to live in part shade, wet to moist situations that replicate its natural habitat, with acidic soil that is sandy or peaty being ideal. It can do well in alkaline soil but will not tolerate dry conditions. Unlike the evergreen holly that is seen in many Christmas decorations, winterberry is deciduous, dropping its leaves in winter.
It is prized for its long-lasting red berries that persist well into the winter, brightening the landscape and serving as emergency late-season food for a variety of birds, as well as the occasional white-footed mouse or white-tailed deer. Winterberry has separate male and female plants, and only the females produce berries. At least one male plant is needed for several female plants to ensure production of the berries that follow fertilization of the tiny flowers. Sometimes bisexual flowers are also produced, but the best way to be sure of fruit set is to have both male and female plants. Winterberry is often sold unsexed, so it’s a good idea to plant 3–5 individuals to have a better chance of having at least one of each.
Ilex verticillata can grow to be 6 to 9 feet tall and wide, or larger in an optimal location, so it’s best used in a spacious landscape. It is fairly disease and pest tolerant and works well in many different styles of gardens.
Written by Betsy Seff