The Wintergreen Boxwood (Buxus microphylla ‘Wintergreen’) is a popular, dense, evergreen shrub valued for its fine texture and year-round color in the landscape. This cultivar is widely used for creating low hedges, formal borders, and foundational plantings due to its compact habit. Determining the ultimate size of this durable plant is a primary consideration for proper landscape design. This article details the expected mature dimensions and explores the various influences on its final growth.
Mature Height and Spread
The standard, mature dimensions of the Wintergreen Boxwood typically fall within a predictable range when grown in favorable conditions. This shrub generally reaches a height of 2 to 4 feet and a width of 3 to 5 feet at full maturity. The spread often exceeds the height, resulting in a naturally boxy or rounded form that lends itself well to formal garden designs.
The Buxus microphylla ‘Wintergreen’ is characterized by its slow growth rate. It typically gains about 2 to 3 inches of growth annually, though it can reach 4 to 6 inches in optimal environments. Due to this slow pace, a newly planted shrub may take 10 to 15 years or more to approach its maximum listed size of four feet tall.
This gradual development means the shrub requires minimal pruning to maintain a tidy appearance. The dense, small-leaved foliage retains its vibrant green color throughout the winter, making it a reliable source of structure in colder months. Understanding the long timeline to maturity is important when placing the plant, as it will not quickly overwhelm its designated space.
Environmental Factors Affecting Final Size
The dimensions listed for the Wintergreen Boxwood represent its genetic potential, but the actual size achieved is heavily influenced by the growing environment. Light exposure plays a significant role in determining the shrub’s density and height. While it tolerates full sun to partial shade, plants receiving more shade may develop a looser, more open growth habit as they stretch to capture light.
Soil quality and moisture levels are another determining factor in the overall size a boxwood can attain. The shrub prefers well-drained soil that is rich in organic matter, and poor, compacted, or overly wet soil can stunt its growth. Conversely, planting in an ideal, fertile location with consistent moisture will encourage the plant to reach the upper limits of its expected height and spread.
Climate also impacts the final size, particularly when the shrub is grown at the edges of its hardiness range, generally USDA Zones 4 through 9. Boxwoods grown in the colder limits of this range may experience winter damage or slower growth, resulting in a smaller overall mature size. The differences in sun intensity and season length can shift the final height and width compared to boxwoods grown in the center of their preferred zones.
Controlling Growth Through Pruning
While the slow growth rate of the Wintergreen Boxwood makes size management less frequent than with other shrubs, gardeners often need to maintain a size smaller than its mature dimensions for specific landscape purposes. Pruning techniques manage the shape and size of the shrub, allowing it to fit neatly into formal gardens or alongside walkways. The best time to perform any heavy pruning is in late winter or early spring before the new season’s growth begins.
There are two primary methods for controlling the size and shape of boxwoods: shearing and selective thinning. Shearing involves using hedge trimmers to uniformly cut the outer foliage, which is useful for creating formal, geometric shapes. This method promotes a dense outer layer of growth, which can sometimes shade out the inner branches. Selective thinning involves reaching into the shrub and removing individual branches back to a side bud or main stem. This technique maintains the plant’s natural habit while allowing better air circulation and light penetration to the interior. All pruning should be completed by late summer to avoid stimulating tender new growth that could be damaged by the first winter frost.