The Wax Myrtle (Morella cerifera) is a popular evergreen shrub native to the southeastern United States. It is valued for its dense, year-round foliage, making it a fast-growing solution for privacy screens or natural hedges. Its aromatic, olive-green leaves release a distinct fragrance when crushed, and the plant tolerates various challenging environmental conditions. Understanding its growth speed is important for planning its placement and managing its eventual size.
Defining the Annual Growth Rate
The Wax Myrtle is classified as a fast-growing shrub. Under ideal conditions, the annual growth rate typically ranges from one to three feet per year. In highly favorable environments with extended growing seasons, consistent moisture, and rich soil, some specimens can grow by as much as five feet annually.
This rapid growth is most pronounced when the plant is young and establishing its root system. During the first few years, the Wax Myrtle focuses energy on expansion, quickly filling space to form a dense screen. Although it maintains its fast-growing nature, the rate moderates slightly as the plant matures and approaches its maximum size. This makes it an excellent choice for quick privacy, but requires planning for long-term maintenance.
Environmental Conditions That Impact Growth
Sunlight
The Wax Myrtle’s growth rate is primarily influenced by sunlight exposure. The plant thrives best in full sun, requiring at least six to eight hours of unfiltered light daily. While it tolerates partial shade, growth will be slower, and the foliage may become less dense and more open.
Soil and Water
The shrub is highly adaptable regarding soil, tolerating a wide range of conditions, including sandy, loamy, and poor soils. Optimal growth occurs in well-drained, consistently moist soil that is slightly acidic. Although established plants are drought-tolerant, prolonged dry spells slow annual growth significantly; regular watering encourages maximum expansion.
Climate
Climate plays a decisive role in determining the length of the growing season. The Wax Myrtle is winter hardy across USDA Zones 7 through 11, where growth is continuous throughout the warm months. In warmer, southern limits, the plant remains fully evergreen, maximizing annual growth. In the cooler, northern parts of Zone 7, the plant may become semi-evergreen or experience leaf browning during cold snaps, temporarily slowing development.
Managing the Mature Size and Shape
The Wax Myrtle typically matures into a large shrub or small tree, reaching 10 to 20 feet in height and 8 to 10 feet in width. Due to its vigorous growth, regular maintenance is required to keep the plant within a desired size and shape, especially when used as a formal hedge. The plant responds well to consistent pruning and can be shaped or cut back without issue.
Pruning to reduce size or shape the plant into a tree form should be performed in late winter while the plant is dormant. This timing minimizes stress and maximizes the subsequent flush of new growth in the spring.
For maintaining a dense hedge, light shearing can be done multiple times throughout the growing season. Selective thinning cuts, which remove entire branches back to a main stem, are preferable to simply trimming the tips. This technique improves air circulation and light penetration into the plant’s interior.