Blackhaw Viburnum ( Viburnum prunifolium) is a versatile native plant valued for its appeal in diverse landscapes. This deciduous shrub or small tree typically grows to a height and spread of 12 to 15 feet, though it can reach up to 30 feet when cultivated as a single-trunked tree. Beyond its aesthetic qualities, Blackhaw Viburnum offers significant ecological benefits, providing food and habitat that attract local wildlife.
Blackhaw Viburnum in Winter
Blackhaw Viburnum sheds its leaves in the fall, revealing its structural beauty. Before leaf drop, the foliage transforms into striking shades of red, purple, orange, and bronze. Throughout winter, the plant’s bare branches, often arching, contribute architectural interest to the dormant landscape.
A distinctive winter feature is the persistence of its dark blue-black, berry-like fruits, known as drupes. These fruits, which ripen from a pink-rose hue, often remain on the plant well into the colder months, serving as a valuable food source for birds and other wildlife. The bark of mature Blackhaw Viburnum adds visual appeal, developing a fissured and blocky texture in shades of reddish-brown, while younger stems may exhibit a reddish tint with a pinkish bloom.
Winter Hardiness
Blackhaw Viburnum demonstrates resilience to cold temperatures. It thrives across USDA plant hardiness zones 3 through 9. Its cold tolerance makes it a reliable choice for many regions. Once established, Blackhaw Viburnum also shows good tolerance to drought and can adapt to a wide array of soil types.
Preparing Blackhaw Viburnum for Winter
Proactive measures in late fall and early winter supports Blackhaw Viburnum through the colder months. Adequate late-season watering is important, particularly for younger plants or during dry periods. Deep, infrequent watering (every two to three weeks in winter) ensures the soil is moistened to a depth of 8 to 12 inches. This practice helps the plant store moisture, reducing winter stress.
Applying a 2 to 3-inch layer of organic mulch around the plant’s base provides multiple benefits. Mulch regulates soil temperature, insulates roots from extreme cold, retains soil moisture, and suppresses weed growth. Keep the mulch a few inches away from the trunk to prevent moisture buildup and rot.
Dormant pruning, ideally in late winter or early spring before new growth, involves removing dead, damaged, or diseased branches to maintain plant health and structure. Thinning inner branches improves air circulation and overall vigor.
While Blackhaw Viburnum is generally deer-resistant, newly planted or very young specimens may benefit from temporary protection, such as a wire cage, to deter browsing during food scarcity.
Addressing Winter Challenges
Even with preparation, Blackhaw Viburnum may encounter challenges during or immediately following winter. Winter desiccation, which occurs when plants lose more moisture through their leaves and stems than they can absorb from frozen soil, can manifest as browning or scorching of leaf edges, even on dormant plants. Ensuring consistent, deep watering into late fall and early winter, especially during dry spells, can mitigate this risk.
Heavy snow or ice accumulation can cause branches to bend or break. While Blackhaw Viburnum’s sturdy structure offers some resistance, gently remove heavy snow from branches with a broom or soft tool to prevent damage. Avoid knocking off ice, as this can cause more harm than good.
Any broken or splitting branches should be pruned cleanly back to a healthy branch union once the threat of further ice or snow has passed. Extreme cold or rapid temperature fluctuations can also stress the plant, potentially leading to bark splitting or dieback. However, due to its hardiness, this is less common for Blackhaw Viburnum.