Winterthur viburnum

Sun

Full sun to partial shade; flowering, fruiting and autumn colour are usually strongest with plenty of sun.

Water

Keep the soil evenly moist, especially during establishment and dry summers. Established plants tolerate occasional wet soil better than prolonged drought.

Soil

Moist, humus-rich, acidic to neutral soil. Tolerates clay and periodically wet ground, but avoid very dry or strongly alkaline sites.

Height

5-6 ft (1.5-1.8 m)

Spread

5-6 ft (1.5-1.8 m)

Flowers

Late spring to early summer; small creamy-white flowers in broad, flat-topped clusters.

Foliage

Glossy, oval, dark green leaves turn burgundy, wine-red or reddish purple in autumn.

Growth

Moderate

Care needed

Low

• Pollinators
• Heat tolerant
• Wildlife
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1.6 ft (0.5 m)

2. After 1 year

   2.4 ft (0.73 m)

3. After 2 years

   3 ft (0.96 m)

4. After 3 years

   4 ft (1.2 m)

5. After 5 years

   5 ft (1.7 m)

   full size

About 5 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Native to

the US and Canada

Growth rate

Moderate

• Water deeply during dry spells for the first two growing seasons, then during prolonged drought.
• Apply 2-3 in (5-8 cm) of organic mulch over the root area, keeping it clear of the stems.
• Plant a genetically different Viburnum nudum, such as 'Brandywine', nearby for better berry production; another 'Winterthur' is the same clone.
• Top-dress with compost in spring; use fertiliser only if growth is poor or a soil test identifies a deficiency.
• Allow room for its natural rounded shape rather than maintaining it as a tightly clipped hedge.

Pruning. Prune only as needed immediately after flowering, removing damaged or crossing branches and shortening wayward shoots. Heavy pruning removes developing fruit, so keep it light if berries are a priority.

Early spring

Refresh the mulch and remove dead or winter-damaged wood.

Spring

Plant container-grown shrubs while the soil is moist; add a different Viburnum nudum selection if fruiting has been poor.

Late spring to early summer

After flowering, make any necessary light shaping cuts, leaving most flower clusters to develop fruit.

Summer

Water during dry spells and check leaves for beetle damage or mildew.

Late summer to autumn

Leave ripening berry clusters for birds and enjoy the changing fruit and leaf colours.

Autumn

Plant new shrubs where winters are mild, and water thoroughly before the ground freezes in colder areas.

• Use in a mixed shrub border with oakleaf hydrangeas and sweetspire for contrasting foliage and a long autumn display.
• Plant as an informal hedge or boundary screen, allowing its rounded shape and fruit clusters to remain intact.
• Place along a pond margin or in the moist part of a rain garden, above permanently submerged ground.
• Combine with ferns and sedges at a woodland edge for a layered, natural-looking planting.

Garden styles it suits: Woodland, Wildlife garden, Autumn colour, Native hedgerow, Low-maintenance and Traditional.

Plant it with: Oakleaf hydrangea, Virginia sweetspire, Summersweet, Winterberry holly, Cinnamon fern and Tussock sedge.

Wildlife: Flowers provide pollen and nectar for visiting insects, and ripe berries feed birds. The dense branching also offers shelter; its strongest native wildlife connections are in eastern North America.

• Few or no berries: plant a different, compatible Viburnum nudum selection with overlapping flowering; two 'Winterthur' shrubs do not provide genetic cross-pollination.
• Viburnum leaf beetle: where this pest occurs, inspect young leaves for feeding larvae and remove affected shoots or larvae early; prune out egg-bearing twig tips during dormancy.
• Powdery mildew or leaf spots: provide air circulation, water at soil level and clear badly affected fallen leaves.
• Yellow leaves with green veins: alkaline soil can limit iron uptake; test the soil and favour a naturally acidic planting site rather than repeatedly applying corrective products.

Not known to be toxic to people, cats, dogs or horses. It is grown as an ornamental, not a food crop; eating large quantities of berries or other plant material may cause stomach upset.

• Witherod (Viburnum cassinoides)

  Very similar, with comparable fruit colours, but its leaves are generally duller and less glossy. Identification can be difficult without checking several botanical features.

• Blackhaw (Viburnum prunifolium)

  Usually becomes a larger shrub or small tree and has distinctly finely toothed leaf margins; Winterthur's leaf margins are mostly smooth or only faintly toothed.

• Laurustinus (Viburnum tinus)

  Keeps its leaves through winter and usually flowers in winter or early spring, unlike deciduous Winterthur, which flowers in late spring to early summer.

The cultivar name 'Winterthur' refers to the Winterthur estate in Delaware, where this selection originated.

Propagation. Take softwood cuttings in late spring or early summer, or layer a low branch. Seedlings will not reliably retain the characteristics of 'Winterthur'.

Accepted botanical name

Viburnum nudum

In the US and Canada

Native in Canada, the lower 48 states and St. Pierre and Miquelon.

Native range

Alabama, Arkansas, Connecticut, Delaware, District of Columbia, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi and New Jersey.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.