Last week I discussed hydrangeas. This week I feel it is only appropriate that I cover viburnums. Many people confuse these two groups of shrubs since they have many similar features.
There are numerous different species of both, but far more species of viburnums exist than hydrangeas. There are over 150 different viburnum species and numerous cultivars of many. From a distance, both often look similar. Upon closer inspection, viburnum buds are basically upright, while hydrangea buds tend to lay down more.
Both have leaves that emerge from stems in groups of two. Hydrangeas and viburnums usually have large flower clusters. The snowball viburnum looks a lot like the snowball hydrangea. Both have large clusters of white flowers.
In general, viburnums have more fragrant flowers, and flowers are almost always white. A few are pink. Korean spicebush and Burkwood viburnum are white and especially fragrant. Most viburnums also usually grow much taller than hydrangeas.
Being taller, viburnums are often less suited for use in foundation plantings. They might be more appropriate for taller buildings though. Their primary landscape use is as accent or specimen plants.
These versatile shrubs can grow in full sun to partial shade. Some types do better in sun, while others like ‘Chindo’, a cultivar with shiny leaves, can tolerate moderate shade. Most viburnums prefer well-drained soils and endure drought very well once established.
Viburnums almost always bloom on the previous season’s wood. This means that viburnums should never be pruned in the fall. Most types bloom in early spring. One should deadhead blooms and prune the plants when flowers start dropping their petals. Otherwise, no pruning is necessary.
As far as hardiness goes, viburnums display a wide range. Many are hardy in northern Canada, while others are adapted to the deep south. Some are deciduous, and other types are evergreen. Still, others are semi-evergreen. This means that in mild winters plants often keep most of their leaves, while in hard winters they lose them.
One nice thing about landscaping with viburnums is that they respond well to renewal pruning, so if plants begin to get too large, they may be cut to the ground much like forsythia can. New shoots will spring up and the training process can begin again.
Most viburnums usually set fruit, which is utilized by wildlife. Highbush cranberries have red fruit that hangs in clusters and resembles cranberries. They are totally unrelated to true cranberries. Other viburnums with red berries are hobblebush and nannyberry. Both have sweet fruit that is delicious fresh and often eaten by wildlife. Fruits make good jelly, too.
Other viburnums can have blue or black fruit. Many of these are edible for humans, but they’re usually sour. Maple leaf and arrowwood viburnums have blue fruits and are highly prized by many different wildlife species. Black haw viburnum is a native black-fruited type that makes beautiful dark jelly.
With a huge array to choose from, viburnums should find their way into almost any landscape. Most are native and that is important to many gardeners, also.
Next year’s flower buds are developing now on this snowball viburnum.
Ted Manzer teaches agriculture at Northeastern High School.