Viburnum opulus 'Sterile', commonly known as the Snowball Viburnum or European Snowball Bush, is a stunning deciduous shrub that earns its name from the spectacular, globe-shaped flower clusters — up to 8 cm (3 in) across — that emerge lime-green in bud and mature to pure, luminous white in late spring to early summer. The bold, three-lobed, maple-like leaves emerge fresh green in spring, transition to rich burgundy-red in autumn, providing outstanding multi-season interest. As a sterile cultivar, it produces no fruit, directing all its energy into an exceptionally showy floral display. Vigorous and adaptable, this classic garden shrub makes a dramatic specimen plant, an informal screen, or a striking anchor in a mixed shrub border.
- Mature height: 8–10 ft
- Mature spread: 5-6 ft
- Growth rate: Moderate to fast
- Habit: Upright, arching, multi-stemmed; broadly rounded at maturity
- Hardiness: Zone 3 — reliable prairie performer
- Sun: Full sun to partial shade; best flowering and fall colour in full sun
- Water: Moderate; prefers consistent moisture, especially during establishment; tolerates brief periods of wet soil
- Soil: Adaptable to a wide range of soils; prefers moist, well-drained, fertile soil; tolerates clay
- Fertilizing: Apply a balanced slow-release fertilizer in early spring; avoid excess nitrogen
- Pruning: Prune immediately after flowering to preserve the following year's buds; remove one-third of the oldest stems every few years to rejuvenate; avoid heavy shearing
- Pests: Monitor for viburnum leaf beetle (Pyrrhalta viburni) — inspect leaves for egg-laying sites in winter and remove affected twigs; hand-pick larvae in spring if populations are low
- Fall interest: Excellent burgundy-red autumn foliage colour adds a second season of ornamental value