Ilex verticillata Oosterwijk - Winterberry, Black Alder

The Ilex verticillata 'Oosterwijk' is a female variety of holly, known for its abundant bright red fruiting that beautifies the garden until the end of winter on its bare branches. Originating from Canada and the northeastern United States, this holly is extremely hardy. Its leaves, which fall in autumn, are not prickly, unlike those of the European common holly. Ornamental almost all year round, 'Oosterwijk' is perfect for a natural garden, a free hedge, as well as for moist areas and riverbanks, where it thrives particularly well. For optimal fruiting, it is necessary to pollinate it with a male plant, such as 'Southern Gentleman', recommended for its simultaneous flowering.

The holly belongs to the Aquifoliaceae family. The Ilex verticillata is a suckering and very ubiquitous shrub, liking acidic soils and cool to wet areas, but also adapting to open spaces like meadows or occasionally drier soils of dunes. It is found in a large part of the North American territory. It is quite polymorphic, taking on the appearance of a large spreading shrub 5m in height by 6m in width, or the more modest form of a narrow shrub not exceeding 2m in height, depending on its habitat. This species is dioecious, meaning there are male and female subjects.

'Oosterwijk' is a very floriferous female selection, with an erect and rounded habit, reaching approximately 2m in all directions. The foliage, deciduous in winter, consists of obovate or lanceolate leaves, long and slender, measuring 3 to 9cm, and featuring toothed edges. The young spring shoots take on a purple tinge. On adult leaves, the blade is bright green and shiny on top, lighter and downy underneath. The autumn colours in shades of orange-yellow with bronze or coppery reflections are beautiful. Flowering occurs in spring, in the form of small white flowers not exceeding 5mm in diameter. When pollination occurs, the female flowers transform into small, shiny, globular red fruits, grouped in small clusters. They delight birds in winter.

Ilex verticillata 'Oosterwijk' meets the expectations of gardeners looking for resilient, colourful shrubs that are easy to maintain. It is particularly appreciated for the beautiful touch of colour it brings to the garden, especially in winter, when its branches are adorned with bright red berries. It blends perfectly in a mixed hedge, alongside 'Zempin' Elaeagnus, coyote willow, Cotoneaster lacteus, deciduous euonymus, or elderberries. Susceptible to limestone which can yellow its foliage, it prefers moist to wet soils. Very hardy, it withstands temperatures well below -15°C and thrives near water points and on waterlogged land. Some gardeners choose to prune it into the shape of a small fir tree, creating a winter spectacle of striking red trees. Ideal for cold regions, it pairs well with hawthorns, snowberries, pyracanthas with yellow or orange berries, and other evergreen hollies.