Blackhaw viburnum (Viburnum prunifolium) is a deciduous shrub with an upright growth habit, almost growing as wide as it is tall. It can be trained to grow as a small tree with a single trunk. Its rough bark is a reddish-brown color, and it sports ovate, glossy dark green leaves that stretch about 4 inches long. In the late spring, clusters of small white flowers appear, followed by yellow berries that mature to a blue-black color. Birds and other wildlife are attracted to these fruits, and humans can eat them as well. In the fall, the foliage turns to shades of red and purple. This shrub grows at a moderate rate and is best planted in the early spring or fall.
|Botanical Name||Viburnum prunifolium|
|Common Names||Blackhaw viburnum, blackhaw, black haw, sweet haw, stag bush, sheepberry|
|Plant Type||Perennial, shrub|
|Mature Size||12–15 ft. tall, 6–12 ft. wide|
|Sun Exposure||Full, partial|
|Soil Type||Moist, well-drained|
|Hardiness Zones||3–9 (USDA)|
|Native Area||North America|
Blackhaw Viburnum Care
Blackhaw viburnum is a low-maintenance shrub that grows well in many different locations and climates. Selecting a spot for your shrub that has good soil drainage and ample sunlight is key to making its care a breeze. Make sure to account for the shrub’s mature size to give it enough space when planting.
This shrub is quite hardy and doesn't typically have any serious issues with pests or diseases. It has a good tolerance for pollution, as well as for being planted near black walnuts and other walnut tree species, which release a substance that’s harmful to many plants. In terms of its regular care, plan to water during dry spells and feed your shrub annually. Pruning also is typically an annual chore to maintain the shrub’s size and shape.
This shrub prefers to grow in full sun or partial shade, meaning it needs at least three hours of direct sunlight on most days. The best flowering and fruiting will occur in higher levels of sunlight. However, it's ideal to provide the shrub with some afternoon shade in the hottest parts of its growing zones.
Blackhaw viburnum will tolerate a variety of soil types as long as it has good drainage. It thrives in loamy soil but also can handle sandy or clay soil. Moreover, it prefers a neutral soil pH but can tolerate slightly acidic to slightly alkaline soil as well.
This shrub has moderate water needs. Keep the soil for young shrubs evenly moist (but not soggy) as they establish their root systems. Mature shrubs have some drought tolerance and generally will only require watering if you have a prolonged period without rainfall and/or are experiencing hot temperatures.
Temperature and Humidity
Blackhaw viburnum is hardy both to hot and cold temperatures. It can tolerate temperatures around 90 degrees Fahrenheit as long as its moisture needs are met. And it will survive conditions below freezing, though once frost hits in the fall is when it starts to lose its leaves for winter. Humidity typically isn’t an issue for the shrub. In very high humidity it’s important to ensure good air flow around the plant to prevent fungal diseases. And in dry conditions, a layer of mulch over the root zone can help to retain soil moisture.
The shrub will benefit from an annual feeding in the spring, especially if you have poor soil. Use a balanced, slow-release fertilizer around the plant, following label instructions.
Propagating Blackhaw Viburnum
You can propagate blackhaw viburnum by germinating the seeds. Save seeds by harvesting the fruit once it turns its black-blue color and drying the berries (with pulp) in a cool location. Once dry, store the seeds over the winter in a brown paper bag in a cool, dark spot. Plant them in small pots in the early spring in a seed-starting mix that you keep lightly moist. Keep the pots in a bright, warm spot as they germinate. Then, transplant the seedlings outdoors when they're about a foot tall. Make sure to bring the young plants outside for gradually longer stretches for about a week to acclimate them to direct sun.
Prune your shrub right after it’s done flowering. Buds for the next year start forming in the summer, so there’s only a small window after the shrub’s spring bloom when you won’t accidentally remove some of next year’s flowers via pruning. The shrub has a somewhat irregular shape, and by letting it take its natural shape you won’t have to do much pruning to keep it tidy. Thin out stems that are growing very close to one another to improve air flow throughout the shrub and allow sunlight to hit all parts of it. And only slightly prune the tips of the stems if you wish to control the shrub’s size, as heavy pruning can damage its form. Remove any dead, diseased, or damaged portions as they arise.
Blackhaw Viburnum Varieties
There are several varieties of blackhaw viburnum, including:
- Viburnum prunifolium 'Guazam’: This shrub grows slightly smaller than the main species plant and features dark green leaves that turn crimson in the fall.
- Viburnum prunifolium 'McKrouge’: This variety also is slightly smaller than the species shrub, and its foliage turns a maroon color in the fall.
- Viburnum prunifolium 'Summer Magic’: The foliage on this variety emerges a reddish-pink color and turns yellow to red in the fall.