The Wintergreen Boxwood, formally known as Buxus microphylla ‘Wintergreen’, is a dense, broadleaf evergreen shrub highly valued in landscaping across many regions. Its compact growth habit, fine-textured foliage, and exceptional resistance to winter bronzing make it a favored choice for formal gardens, low hedges, and foundation plantings. Gardeners often select this plant for its predictable shape and structure, but understanding its rate of development is important for long-term design planning. This article addresses how quickly the Wintergreen Boxwood grows and what influences its speed.
Defining the Growth Rate of ‘Wintergreen’ Boxwood
The Wintergreen Boxwood is generally classified as a slow-to-moderate grower. Under typical conditions, this variety adds between three and six inches of new growth per year once the plant is established. This rate is considered fast within the boxwood family, which is known for its slow development, but it is slow compared to most ornamental shrubs.
This controlled expansion means the shrub requires very infrequent pruning to maintain a specific dimension or form. The slow pace of growth is an advantage for creating detailed garden elements like topiary or low borders, and allows the shrub to be used effectively in small spaces without quickly outgrowing its position.
Environmental Factors Influencing Growth Speed
Achieving the maximum growth rate of six inches annually depends heavily on providing ideal growing conditions. Sunlight exposure is a significant factor; while Wintergreen Boxwood tolerates full sun, it often thrives best in locations that receive partial shade. Protection from intense afternoon sun is especially important in warmer climates, as harsh sun can stress the plant and slow its growth.
Soil quality and moisture management also play a large role in the plant’s vigor. Boxwoods require well-drained soil and will struggle in heavy, waterlogged conditions that restrict oxygen to the roots. A slightly acidic to neutral soil pH is preferred. Consistent soil moisture is necessary, particularly during the first two years of establishment and throughout periods of drought.
The climate, defined by the USDA Hardiness Zone, dictates the length of the active growing season. The Wintergreen Boxwood is notably cold-hardy, thriving across zones 4 through 9. Plants at the colder end of this range will have a shorter growing window, which naturally limits the total inches added each year compared to those in warmer zones. Proper site selection that accounts for these environmental variables is the first step toward encouraging healthy development.
Techniques for Managing and Controlling Size
Gardeners can actively intervene to either accelerate growth or precisely control the shrub’s dimensions. To encourage maximum annual growth, a balanced fertilizer application is recommended in early spring before new growth begins. Fertilizers with a high nitrogen content support the dense, green foliage, but they should be applied lightly to avoid burning the shallow root system.
For established plants where size maintenance is the goal, pruning techniques are applied. Pruning should be done in early spring, just before the main flush of growth, or repeated lightly through the summer to shape the plant. When maintaining a tight hedge, shearing the outer tips encourages a dense shell of foliage. However, occasional selective thinning of inner branches is important to allow light penetration and air circulation to the shrub’s interior.
Avoiding pruning and heavy fertilization after mid-summer is important. Late-season growth stimulated by these actions may not harden off sufficiently before winter, leading to potential cold damage. For gardeners seeking to severely restrict annual growth, specialized plant growth regulators can be applied. These compounds contain hormones that shorten the distance between leaf nodes, effectively limiting the overall size increase while maintaining a dense appearance.
Ultimate Mature Dimensions and Lifespan
The ultimate size of a Wintergreen Boxwood provides context for its slow growth rate. If left unpruned and grown in optimal conditions, this shrub typically reaches a mature height of three to four feet. Its spread is often slightly wider than its height, commonly filling out to four to six feet across.
Because of its slow and steady development, the Wintergreen Boxwood is considered a long-lived landscape plant. It takes many years to fully mature, with lifespans that can extend for decades. This longevity, combined with its compact size, ensures that the initial landscape design remains stable for a substantial period.