Viburnums - Spring's Snowy Blooms (p.24)

By Tina Mast

If spring were a wedding, then daffodils, Lenten roses, and forsythia would be bridesmaids, and viburnum would be the sweet bride entering last, arrayed in white and lace. Viburnums and other white-blooming spring flowers offer a charmingly graceful counterpoint to the wild ruckus of azaleas that explodes through southern gardens every spring. There are many varieties of viburnum and plenty of them are excellent garden plants. Not only do many of them have multi-season interest, most viburnums have few pest or disease problems.

Justice can’t remotely be done to all of them here but following are a few popular, showy types that steal the show and the hearts of gardeners everywhere they grow. Most viburnums prefer sun to part-shade and moist, well-drained soils and can get pretty grumpy about being planted in hot, dry soils. Afternoon shade is not a bad thing when it comes to growing many viburnums. Note that a few cultivars are counter-intuitively named ‘Sterile’. In the case of viburnums, when you see the name ‘Sterile,’ don’t think “lifeless” or “drab” – instead think “big, fat flower clusters.”

'SHASTA' DOUBLEFILE VIBURNUM
(Viburnum plicatum var. tomentosum ‘Shasta’) – A large shrub of regal bearing with extremely showy, bright white lace-cap flower clusters running down the tops of each branch, this stunner will happily flower in both sun and shade. The shrub itself, which will grow to about 8’ tall and significantly wider, has lovely tiered branches for a layered, wedding-cake look and handsome pleated foliage in bright green. This viburnum is planted out in the front border of our nursery, and every year we get the same question: “What’s that big beautiful shrub out front that looks a lot like a dogwood?” There are several other common cultivars in this group (i.e. ‘Mariesii’ and ‘Lanarth’) and the flowers typically have a white lace-cap form. Fall leaf color is often a fine burgundy red, and clusters of small cherry-red fruits that turn black are produced much to the satisfaction of local birds. If you have clay soil, amend it well with soil conditioner as the Shasta viburnum won’t tolerate heavy, damp soil. For ‘Shasta,’ a little afternoon shade is preferred.

CHINESE SNOWBALL VIBURNUM
(Viburnum macrocephalum ‘Sterile’) – This is your Grandma’s snow-
ball bush ... a hefty shrub that will grow into a dense, rounded 14’ specimen with age decking itself out in massive fluffy globe-shaped blooms each spring. The lavish flowerheads, up to 8” wide, emerge bright apple green and age to a gorgeous snowy white. People come into the nursery every year asking for this striking plant, whether or not they know what it is. They just know they gotta have it! This plant can be restrained or just knocked back down to a manageable size with a hard pruning, which will sacrifice the following year’s flowers but rejuvenate it nicely.

EUROPEAN SNOWBALL VIBURNUM
(Viburnum opulus ‘Sterile’, ‘Roseum’) – Or maybe this is your grandmother’s snowball bush. Beautiful snowball-like blooms also grace this plant, but in smaller 3” pom-poms. The lobed, maple-like leaves are attractive on their own merits, nicer to my mind than the Chinese snowball’s somewhat coarse foliage. Because it is sterile, neither this nor the Chinese snowball viburnum will set fruit. The “regular” species, however, has flat-topped lace-cap style flowers and is not sterile. In fall, it sets glossy, scarlet fruits in inviting clusters prompting the common name for this plant, the European cranberrybush viburnum (Viburnum opulus). A great feature of both of these plants is that they will tolerate wet, boggy areas, so consider either for that poorly drained area of your garden. Growing to 8’-12’ tall and wide, plant this in a mixed border for a very handsome effect.

KOREANSPICE VIBURNUM
(Viburnum carlesii) – Wafting the spicy scent of cloves over the garden in spring is the lovely Koreanspice viburnum. Its glossy bud clusters start out rosy-coralline pink resembling a tempting bunch of shiny little berries, and then open to small fragrant white flowers. Over time, the shrub becomes dense and rounded to about 4’-8’ tall and wide with upright-spreading branches. This viburnum is a little more drought tolerant than the others mentioned here. While this plant prefers well-drained soils like most viburnums, it will tolerate clay as well. Somewhat similar to Koreanspice viburnum are the Burkwood viburnums such as ‘Mohawk,’ and ‘Conoy’ which also produce wonderfully fragrant white flowers from glossy, dark pink bud clusters.

SUMMER SNOWFLAKE VIBURNUM
(Viburnum plicatum var. tomentosum ‘Summer Snowflake’) – While most of us are satisfied with the three or four magnificent weeks we have with our viburnums in bloom, someone upstairs must have heard the call for a longer-blooming type. ‘Summer Snowflake’ begins producing beautiful and dainty white lace-cap flowers all over the shrub in mid to late spring and repeats through early fall! The foliage is bright green and attractively veined, as with many viburnums, and turns a nice burgundy red in fall. ‘Summer Snowflake’ is said to grow to a nice manageable six feet tall, but reports on this have been conflicting indicating that it is possible for this plant to get up to 15’ tall, with an average of 8’ in height. Generally, it has a pillar-like habit staying narrow to about 4’-6’. Whatever size it gets to, it is not drought tolerant, and will hold off on repeat blooms or even take a permanent vacation if you don’t provide enough water in dry years, so place it in a bed that gets regular water or include it in the scheme for drip irrigation.

VIBURNUMS AT-A-GLANCE
– Bloom Season: Mid to late spring, usually April to May.
– Light: Full to partial sun. Some protection from afternoon sun is nice but not absolutely Required.
– Soil: Generally moist, slightly acidic, and well-drained. Does not like hot, dry soils. See individual listings for more.
– Fertilizer: Apply a slow-release granular fertilizer formulated for trees and shrubs in spring.
– Water: Regular water especially during dry spells. See individual listings for more.

Tina Mast is the Communications Director at Homewood Nursery in Raleigh and can be reached at 919-847-0117 or by email at info@homewoodnursery.com.