In late autumn and winter, Ilex verticillata, our deciduous native holly—commonly called winterberry—comes into its own, and sheds its glossy green leaves to reveal persistent berries that add a vibrant splash of vermillion to our icy, colour-starved landscapes.
Unlike its famous cousin, English holly (Ilex aquifolium, Zone 7), the berries aren't obscured by evergreen foliage, and plants are hardy to Zone 3. In the wild, winterberries are found growing in wet soils beside bogs, streams and lakes from western Ontario to Newfoundland and south to Georgia and Alabama.
Botanists divide winterberries into two groups: southern and northern types (although both are equally hardy). Like all hollies, male and female flowers are produced on separate plants, and while the females generate the eye-catching fruit, they require at least one male nearby for pollination.
For maximum fruiting, it's best to use the early-blooming male I. v. 'Jim Dandy' for northern types, and I. v. 'Southern Gentleman' for late-blooming southern types. Many of the best and most widely available winterberry cultivars are the result of extensive breeding work by Robert C. Simpson at Simpson Nurseries in Indiana in the 1970s and 80s.
In Canada, Ray Fielding of Pleasantville, Nova Scotia, released several varieties, including the fully dwarf I. v. 'LaHave'. More recently, new cultivars have been selected for superior fruit production, earlier leaf drop, and improved disease resistance. And needless to say, the hunt is on for a stable golden-leafed or variegated mutation.
One male plant is sufficient to pollinate a dozen females, but because males don't produce showy winter fruit, I prune back my 'Jim Dandy' every spring to provide a steady supply of "new wood" flowers, and to limit the amount of garden space he requires. My fantastically flashy females all strut their stuff in the front garden, while "Jim" is relegated to an inconspicuous corner of the backyard almost 40 metres away—but the bees seem to figure it out.
Winterberries require plenty of moisture throughout the growing season, so if you lack a lake or permanently moist area, try planting them as I do: beside my eavestrough downspouts. Next January, you'll be very thankful you did.