Keep the shrubs consistently moist. Where pruning is necessary to shape the shrubs or control their size, it should be done immediately after flowering. This protects next’s year’s flowers, as well as the berries, which are much favored by birds.
Light
Grow doublefile viburnum in full sun to part shade locations. Full sun will produce the best flowering.
Soil
This shrub prefers well-drained, loamy, slightly acidic soil but has a wide range of tolerance for most soil types. It does well with other acid lovers, such as azaleas and rhododendrons.
Water
Doublefile viburnum likes to be kept consistently moist, though it will tolerate dry conditions once the shrub is mature.
Temperature and Humidity
Viburnum likes moderate climate conditions. It does not do well in intense heat (though will survive if it has some shade and is mulched to keep the soil cool), and it may experience frost damage if a warm winter concludes with bitter cold at the end of the season.
Fertilizer
Like most viburnums, doublefile will appreciate the application of a balanced, time-release fertilizer mixed into the soil in spring. Additional feeding is not necessary.
Types of Viburnum
The viburnum genus includes a great many species. Some good choices include:
‘Witherod viburnum’ (Viburnum cassinoides): This North American native for zones 3 to 8 reaches 5 to 12 feet in height and width at maturity. Flat-topped clusters of small, white, bad-smelling flowers appear in June in most regions. Fall foliage ranges from orange to red to purple. The edible berries start out green but eventually proceed through shades of red and blue to a color that is almost black in fall (each berry cluster can contain multiple colors at the same time). The berries persist to provide winter interest as they attract birds. ‘Golden wayfaring tree’ (Viburnum var. lantana ‘Aureum’): Grow this shrub in zones 3 to 7. Its mature dimensions are 8 feet tall with a similar spread. The flowers and the berries are similar to those on V. cassinoides, but what distinguishes this bush is the foliage color. The new leaves sport an unusual golden-yellow color that will eventually fade to green unless the plant is grown in the shade. Fall color is also yellow.
Doublefile Viburnum vs. Japanese Snowball Bush
A close relative of the doublefile viburnum is the Japanese snowball bush (viburnum plicatum—doublefile viburnum is actually a form of V. plicaturm). The primary difference is that the flowers on snowball bush are round, full “snowball” blooms, rather than the flat clusters found on doublefile viburnum. There are also cultivars of Japanese snowball bush that offer pink or pink and white blooms.
Pruning
Prune this shrub immediately after flowering. Because the shrubs flower on “old wood,” pruning immediately after flowering gives them time to develop the growth that will become next spring’s old wood. Light pruning can be done at any time, but when rejuvenation is needed every few years, start by eliminated any stems that rub together. Remove a full one-third of all stems, and also remove any water sprouts or suckers at ground level.
Propagating Doublefile Viburnum
Like most viburnums, Doublefile is fairly easy to propagate by softwood cuttings. Spring through July is the best time to take cuttings, as new growth will be present on the branch tips
How to Grow Doublefile Viburnum From Seed
Growing this shrub from seed is a long and lengthy process and can take as much as 18 months for the seeds to germinate. It’s best to grow these shrubs from cuttings.
Overwintering Doublefile Viburnum
Doublefile viburnum shrubs require a bit of care in zones 5 and 6 as they are shallow-rooted plants and can be susceptible to frost. Simply add a layer of mulch around the plant’s base, and do not water after the early fall months. If it looks like extreme weather is coming, you can also wrap the plant loosely in burlap to help protect it.
Common Pests
Although the ‘Mariesii’ cultivar is relatively pest-resistant, it may experience viburnum leaf beetles (Pyrrhalta viburni) and aphids. Spray neem oil on the plant to kill any aphids as soon as you spot them. The leaf beetles are a more serious problem. Control measures should target the larvae, not the adults. The University of Florida Extension suggests biological control, recommending, specifically, “Predaceous insects like the larvae and adults of multicolored Asian lady beetle, larvae of lacewings, and spined soldier bugs….” There are no serious disease problems with doublefile viburnum shrubs.
How to Get Doublefile Viburnum to Bloom
These plants like a lot of sunlight, and too much shade can keep them from showing off those beautiful blooms that appear in April and May. Another issue for your viburnum not blooming could be because of the time of year it was trimmed. This shrub flowers on the older mature wood, and if you pruned it before it flowers or too late in the fall, then it doesn’t have time to grow the branches needed to produce blooms. Always prune right after the shrub has flowered. Another cause for viburnum not producing blooms is the fertilizing of the lawn or surrounding areas. These shrubs tend to like a more acidic, well-draining soil, so if the soil has too much nitrogen, it will produce more leaves than flowers. Fertilize carefully around any areas that have these type of shrubs.
Common Problems With Doublefile Viburnum
Like other kinds of viburnum, doublefile viburnum can occasionally have problems. Usually this happens when the plant is not planted in ideal conditions or is under stress.
Spots on Leaves
Spots on leaves that are black, reddish brown, or pale green, are types of fungus that you should be on the lookout for on your viburnum. These typically can be prevented by not watering with overhead irrigation and keeping the leaves dry. If you do see these spots on any leaves, you can correct it by removing those spotted leaves from the plant, raking up around the area to clean up any infected leaves, and controlling with fungicide sprays.
White or Grayish Growth on Leaves
If you notice a white or grayish-colored growth on the surface of leaves, upper and lower, then most likely the viburnum has developed powdery mildew or downy mildew. As with the spots on leaves, do not use overhead irrigation and follow the same procedures; clear up the plants and surrounding areas, and use a chemical spray.
