The Emerald Green Arborvitae, botanically known as Thuja occidentalis ‘Smaragd’, is a popular choice for homeowners needing a dense, year-round privacy screen or a formal hedge. Its naturally narrow, columnar shape and vibrant foliage make it an attractive landscape element across many climates. While its appeal is immediate, understanding its growth habit is important because this evergreen is known to have a moderate growth rate that is highly dependent on its specific environment and the care it receives.
Defining the Annual Growth Rate
The growth rate of the Emerald Green Arborvitae is generally categorized as slow to medium, which means its vertical growth is steady rather than rapid. Once the plant has established its root system, typically after the first year, it generally adds about 6 to 9 inches of height annually. Some reports suggest that younger, recently planted specimens may experience an initial spurt of up to 12 inches per year in optimal conditions, but this pace usually slows down as the tree matures. This consistent, moderate growth results in the dense, tight foliage that makes it so effective for screening. Its growth pattern is a departure from faster-growing relatives, such as the ‘Green Giant’ Arborvitae.
Environmental Factors Influencing Speed
Several external factors determine whether an Emerald Green Arborvitae achieves the higher end of its potential growth rate. Sunlight exposure is the greatest influence, as the plant thrives best in full sun, requiring at least six hours of direct light daily. Trees planted in partial shade will still grow, but their foliage will be sparser, and their overall growth speed will be significantly reduced.
Soil quality also plays a substantial role in the plant’s vigor and development. This cultivar prefers well-drained, moist soil that is slightly acidic to neutral in pH. Heavy, compacted clay soil or excessively sandy soil inhibits root development and slows growth by restricting nutrient and water uptake.
The local climate and hardiness zone also set natural limits. Extreme heat or cold outside its recommended range can slow the plant’s metabolic processes and divert energy from growth toward survival.
Essential Care Practices for Maximum Growth
Achieving the maximum growth rate requires providing consistent and appropriate cultural care, especially during the first few years. Proper watering is paramount, and the tree benefits from deep, consistent moisture, particularly during dry spells and throughout its establishment period. Overwatering should be avoided, as soggy soil can lead to root rot, but the soil should never be allowed to dry out completely.
Applying a slow-release, balanced granular fertilizer in the early spring can provide the necessary nutrients to fuel healthy growth throughout the season. Fertilization is not strictly required for survival, but it will encourage the fastest possible development. Wait until the plant is well-established before initiating any feeding regime to avoid burning new, sensitive roots.
The application of organic mulch, such as shredded bark, around the base of the tree is a highly effective way to support growth. A two- to three-inch layer helps to moderate soil temperature and retain soil moisture, creating a stable environment for the roots. It is important to keep the mulch several inches away from the trunk itself to prevent moisture build-up that could lead to rot.
Controlling common pests, such as spider mites and bagworms, is another aspect of care that prevents growth stalls. An infestation forces the tree to expend energy defending itself instead of producing new foliage and height. Proactive monitoring and prompt treatment of these issues will ensure the plant remains healthy and continues its steady upward trajectory.
Reaching Maturity and Final Dimensions
The moderate annual growth rate means that patience is necessary when using the Emerald Green Arborvitae for screening purposes. A newly planted tree will typically take between five and seven years to reach a functional screening height of six feet. The plant focuses on developing its root system and density before achieving significant vertical height.
The tree’s ultimate mature height typically ranges between 12 and 15 feet, with a narrow width of about three to four feet. This mature size is reached slowly over a period of 10 to 15 years, depending on the growing conditions. Its relatively compact size at maturity makes it a superb choice for smaller yards or narrow spaces.