Dee Runk boxwood is a tall, narrow evergreen that brings height and elegance to small spaces. Instead of the low, rounded mounds most people associate with boxwood, it grows into a slim column of deep green leaves. That shape makes it a go-to plant for flanking doorways, lining paths and creating narrow privacy screens.
This upright boxwood is a selection of common boxwood, the classic European hedge plant. It keeps the fine texture and rich color of its parent while growing in a tidy, vertical form. It also offers moderate resistance to boxwood blight, which makes it a more dependable choice than some other columnar boxwoods.
Botanical Classification
Dee Runk belongs to the box family, a small group of evergreen shrubs that also includes pachysandra and sweet box. It is a cultivar of common boxwood, the species native to southern and western Europe, North Africa and western Asia.
It is one of several upright forms of common boxwood grown in North America. Others include Fastigiata and Graham Blandy. Each has a slightly different height and width, and Dee Runk falls in the middle, offering a tall but manageable column.
Brief History
Common boxwood has been grown in gardens for more than 2,000 years. Over that time, gardeners have selected plants with many different shapes, from tiny dwarfs to weeping and upright forms. Upright boxwoods have long been used in formal gardens to add height, rhythm and structure.
Dee Runk was selected in the United States and became popular in the 20th century, especially in the Mid-Atlantic and Northeast. Its combination of a narrow shape, good hardiness and moderate disease resistance has kept it in demand. Today, it is widely sold as one of the best tall, narrow boxwoods for home landscapes.
Identifying Characteristics
Dee Runk has small, oval leaves about half an inch to an inch long. They are dark green, glossy and slightly leathery. The leaves grow in pairs on opposite sides of the stem and are densely packed along upright branches.
Its most noticeable feature is its tall, columnar form. Mature plants can reach about 8 feet tall while staying only about 2 to 3 feet wide. It grows at a slow to moderate rate, often a few inches a year.
Its branches grow upward and stay close together, so it naturally holds its narrow shape. Like other common boxwoods, its leaves give off a musky scent, especially in warm weather. In early spring, it produces tiny, pale yellow-green flowers that attract bees but are easy to miss.
Landscape Uses
Dee Runk is ideal as a vertical accent. A pair placed on each side of a front door, gate or garden entrance creates a balanced, formal look. Single plants can mark corners of beds or add height among lower shrubs.
It also makes an excellent narrow hedge or screen. Planted in a row, it forms a tall green wall while taking up very little ground space. This makes it useful along fences, between houses and in small city gardens.
In formal gardens, it adds structure among low boxwood hedges and flower beds. It also grows well in large containers, where it can serve as a living column on patios and terraces. Like other boxwoods, it is deer-resistant, and all parts of the plant are toxic if eaten.
Growing Considerations
Dee Runk is generally hardy from about USDA zone 5 to zone 8. It grows best in regions with moderate summers and winters, including the Mid-Atlantic, Northeast, Midwest and Pacific Northwest.
It grows in full sun to partial shade. In hotter regions, afternoon shade helps prevent leaf scorch. In colder areas, protection from strong winter winds helps prevent winter burn and keeps the leaves green.
Good drainage is essential. Like all boxwoods, it can develop root rot in soggy soil. It grows best in loose, well-drained soil enriched with compost, with a slightly acidic to neutral pH of about 6.5 to 7.0.
Its roots are shallow, so a thin layer of mulch, about 1 to 2 inches, helps keep them cool and moist. Mulch should not touch the stems. Water young plants regularly, and give established plants a deep watering in fall before the ground freezes.
Pruning and Care
Dee Runk naturally keeps its upright shape, so it needs only light pruning. A light trim in late spring, after new growth hardens, keeps the outline tidy. Avoid cutting deeply into the plant, which can open gaps in the dense branches.
Heavy snow and ice can bend or split its tall, upright branches. In snowy areas, loosely tying the branches together with soft twine in late fall helps the plant hold its shape. Brushing off heavy snow after storms also helps prevent damage.
Thinning a few interior branches each year lets in light and air, which helps reduce disease. Light fertilizer in spring can help if growth is weak or leaves look pale.
Pests and Diseases
Dee Runk is rated as moderately resistant to boxwood blight, a fungal disease first found in the United States in 2011. Blight causes leaf spots, black streaks on stems and rapid leaf drop. While Dee Runk is not immune, it performs better than many common boxwood cultivars, including English boxwood and Graham Blandy.
It can still be affected by the boxwood leafminer, whose larvae tunnel inside the leaves, as well as boxwood psyllids and spider mites. Root rot can occur in poorly drained soils.
The invasive box tree moth, whose caterpillars can strip boxwoods of their leaves, has spread across Europe and into parts of North America. Gardeners should watch for webbing and chewed leaves in late spring and summer.
Dee Runk vs. Other Upright Boxwoods
Dee Runk is often compared with other columnar boxwoods. Fastigiata grows taller, often reaching 10 to 12 feet, and slightly wider, about 3 to 4 feet. Like Dee Runk, it is moderately resistant to boxwood blight.
Graham Blandy is even narrower, sometimes only 1 to 2 feet wide, but it is highly susceptible to boxwood blight. Green Mountain, a hybrid boxwood, forms a broader pyramid about 5 feet tall. For gardeners who want a tall, slender boxwood with moderate disease resistance and a manageable height, Dee Runk is an excellent choice.
Frequently Asked Questions
How tall does Dee Runk boxwood get? Dee Runk usually grows about 8 feet tall at maturity. It reaches this height slowly over many years. Light trimming can keep it shorter if needed.
How wide does Dee Runk boxwood get? It typically stays about 2 to 3 feet wide. Its narrow shape makes it ideal for tight spaces. It holds this slim form naturally with little pruning.
Is Dee Runk boxwood resistant to boxwood blight? It is rated as moderately resistant to boxwood blight. It is not immune, but it performs better than many common boxwoods. Good spacing and watering at the base of the plant help reduce the risk.
How far apart should Dee Runk boxwoods be planted for a screen? For a dense screen, plants are usually spaced about 2 to 3 feet apart. Closer spacing fills in sooner, while wider spacing improves airflow. Better airflow helps lower the risk of disease.
Can Dee Runk boxwood grow in containers? Yes, it grows well in large containers and makes an attractive vertical accent on patios. Potted plants need regular watering and good drainage. In cold climates, containers should be protected in winter.
How do you protect Dee Runk boxwood from snow damage? Loosely tying the upright branches together with soft twine in late fall helps prevent splitting. Gently brushing heavy snow off the plant after storms also helps. Avoid shaking frozen branches, which can cause them to snap.
Sources
Cornell University, “Woody Plants Database: Boxwood”