Most of us have never heard of this deciduous holly called winterberry — evergreen hollies are far better understood and much more commonly seen in residential arenas. However, for gardeners in cold climates, winterberry provides a lot. It’s easy to love this species and its numerous cultivars, which provide outstanding late-season color.
Botanical name: Ilex verticillata
Common names: Winterberry, Michigan holly, coralberry, black alder
Origin: Native to the eastern United State
Where it can grow: Hardy to -40 degrees Fahrenheit (USDA zones 3 to 9; find your zone)
Water requirement: Moderate to moist soil; adapted to swamps and stream banks
moderate requirement: Full sun to partial shade
Mature size: 6 to 10 feet tall and wide
Benefits and tolerances: exceptionally flexible; appropriate for swales, rain gardens, catchment basins or denuded areas with poor soils
Seasonal curiosity: Late autumn through winter
When to plant: Early spring to late autumn
Distinguishing attributes. Easy-care winterberry stands in a class of its own, as several shrubs can match the brilliance of its winter color. It’s also disease resistant and trouble free, making a fantastic alternative to spirea or Japanese barberry (which could be invasive).
While its blossoms are inconsequential, following pollination in early summer that they swell into green fruits (drupes) that change color with the shorter days and the onset of frost, bringing cedar waxwing, grosbeak, cardinals, juncoes and other birds. Anticipate your shrubs to be stripped bare by winter’s end.
How to use it. There are lots of cultivars to choose from, based upon your location and needs. Here in the U.S. Botanic Garden’s National Garden in Washington, D.C., winterberry (also sometimes called deciduous holly) is used to soften an irregular fitted stone path. It has planted en masse to make a large impact in late autumn when pretty much anything is winding down, with the exclusion of asters.
Though the foliage does not have any significant fall color, the fruits are lovely, particularly the orange hued I. ‘Winter Gold’. For a low-impact native backyard, combine it with airy switchgrass (Panicum virgatum) and narrow-leaved bluestar (Amsonia hubrichtii), each of which can be cold hardy to USDA zone 4.
Winterberry is a superb choice to draw birds and other wildlife into naturalistic regions along woodland edges, but it also creates a fantastic focal point in a sunny bed, where its color will draw on the eye throughout winter.
I. ‘Red Sprite’ is a compact dwarf form that grows 3 to 5 feet tall; it is a fantastic plant for massing along a slope or an entrance to a residence or commercial building. I. ‘Sparkleberry’, a U.S. National Arboretum introduction, grows to 15 feet and can be used as a small tree.
Planting notes. All these are dioecious shrubs, together with male and female plants, and that means you’re going to need a man to ensure decent fruit set. Your nursery or a landscape specialist can guide you into the ideal pairings; that I. ‘Southern Gentlemen’ and I. ‘Jim Dandy’ would be the most common male cultivars.
The plants do best in acidic soils with a pH range of 4.5 to 6.5, so keep them away from real bases and paths, or amend the planting holes to boost pH levels.
Gardeners in snowy northern zones know the worth of winter gardens that are designed to maintain interest throughout the long run of dormancy. Cut branches of winterberry make festive structures, too.
More: Native Plants Inspire and Educate in NYC’s Botanical Garden