Blackhaw Viburnum, bearing the scientific name Viburnum Prunifolium (vy-Bur-num, proo-ni-FOH-lee-um), belongs to the genus Viburnum (like viburnum plicatum) from the family Adoxaceae, commonly known as the moschatel family.
Viburnum was historically included in the Caprifoliaceae or honeysuckle family but was then reclassified on the basis of molecular phylogeny.
Phylogeny is the study of the evolution of a species or a group of genetically-related organisms.
Molecular phylogeny (or molecular phylogenetics) is a branch of phylogeny which investigates the relationships between various organisms on the basis of their genetic and hereditary molecular differences.
Viburnum is the Latin name for the wayfaring tree and Prunifolium means having leaves like a plum.
Native to eastern and central North America, where it is found from Connecticut to eastern Kansas to Texas and Alabama in the south of the United States, viburnum prunifolium is a flowering plant species with several common names.
Some of its widely used common names include:
- Blackhaw – sometimes written as black haw
- Blackhaw viburnum
- Sweet haw
- Stag bush
- Smooth blackhaw
- Smooth blackhaw viburnum
The plant is also sometimes considered similar to hawthorns.
Hence, the common name blackhaw.
However, both are different plant species.
It is also sometimes confused with viburnum lentago (nannyberry).
Blackhaw is a threatened Viburnum species in Connecticut.
Viburnum Prunifolium Care
Size & Growth
Featuring rough stems and ovate, glabrous, and finely serrated leaves, blackhaw is a deciduous shrub which grows as a large shrub or small tree with the height varying between 7’ to 30’ feet.
The plant typically features a short and crooked trunk with several stout branches.
The branches continue to change color as they emerge and grow.
They are red at first, then turn green and eventually become reddish-brown upon maturity.
The texture of the stems also changes with time, becoming increasingly rough as they grow old.
The leaves of blackhaw viburnum generally grow over 3” inches and are attached to the plant with small and slightly winged petioles, which turn red in the fall season.
The leaves of sweet haw are somewhat similar to the leaves of some Prunus species – hence, the botanical name prunifolium.
The young leaves are shining green with a tinge of red and sometimes covered with small, fine, and soft hair, called tomentum.
However, they turn dark green and become smooth from above upon reaching maturity.
The foliage of smooth blackhaw remains attractive throughout the year with dark green color during the summer months and purple to red –burgundy in the autumn.
The plant has a slow to medium growth rate.
Flowering and Fragrance
In mid to late spring, the stag bush plant produces small creamy white flowers in flat-topped cymes.
While the flowers are small and non-fragrant, they are showy and give the plant a beautiful appearance during the bloom time.
The white flower color looks great against the dark green foliage.
The plant is typically in full bloom in April and May.
Flowering is followed by the production of dark blue-black berry-like drupes that remain on the plant until winter.
The fruits serve as wildlife food, especially during the cold weather when food sources get limited.
The black fruits are also edible for humans.
Light & Temperature
Smooth blackhaw requires both sunlight and part shade to grow properly.
For best results, grow the plant at a location where it receives full sun for at least 4 hours in a day and partial shade and partial sun at other times, preferably in the afternoon.
Be careful to not place the plant in full shade for prolonged periods of time.
While the plant can tolerate shade, it has a negative effect on both the flowering and production of fruits.
As long as the plant receives enough water, it can tolerate hot temperatures – up to 90° degrees Fahrenheit (32° C).
It is also fairly winter hardy, often surviving in temperatures even below the freezing point.
The plant is very hardy and grows in USDA hardiness zones 3 to 9.
Watering and Feeding
The viburnum plant prefers moist soil. Therefore, it requires adequate watering to grow well, especially during the first growing season.
However, once established, it becomes fairly drought tolerant.
Black haw bush benefits from spring feeding.
Apply a balanced (10-10-10) granular fertilizer at the base of the plant, creating about 3’ feet wide circle.
Soil & Transplanting
The plant adapts to a variety of soil types quite easily as long as they are moist and well-drained.
However, it produces the best growth when planted in rich loamy soil.
This North American native plant responds well to transplanting.
Early spring and fall are the best times to transplant this viburnum species.
Grooming and Maintenance
Viburnum prunifolium is quite easy to grow as well as hardy.
So, it doesn’t need much care and maintenance to stay healthy and happy.
However, prune it to maintain a tidy appearance.
When needed, prune the blackhaw plant immediately after the flowering season.
How To Propagate Blackhaw Viburnum
Stag bush plants will grow from seeds.
Collect the fruits as soon as they ripened and get a dark blue-black color and dry them (with pulp) at a cool place.
Once the fruits are completely dried, store the seeds in a brown paper bag over the winter season and then sow them in small pots during the early spring.
Let the young plants grow up to 1’ foot before transplanting them outdoors.
Blackhaw Viburnum Pest or Diseases
Sweet haw is one of those plant types which aren’t very susceptible to pests and diseases.
However, it may get affected by aphids, scales, or borers. For control use Neem Oil.
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Rarely, the plant may develop cankers or powdery mildew.
Blackhaw plant contains an element called salicin, which is chemically similar to aspirin.
Therefore, people who are allergic to aspirin should avoid consuming any part of the plant or a product made from it.
While the fruit is consumed by some people, especially some Native American tribes, blackhaw isn’t characterized as a food substance safe for consumption.
It is not listed on the GRAS (Generally Recognized as Safe) list issued by the FDA.
Viburnum Prunifolium Uses
The showy spring flowers of the stag bush make it a popular choice for gardens.
In addition to being grown for ornamental purposes, the plant is also cultivated in some areas for its medicinal properties.
Meskwaki, a Native American tribe, also grows the plant for its fruits.
People of this tribe eat the raw fruits as well as use them to make a jam.
This viburnum species is also a great choice for wildlife gardens, as it attracts a number of birds and butterflies, which also act as pollinators.
Since the plant grows as a large and dense shrub, it is often used as a hedge plant and screen plant.
The showy fall color of its foliage also makes black haw a great choice for winter gardens.