The Emerald Green Arborvitae (Thuja occidentalis ‘Smaragd’) is a favored evergreen in landscaping, known for its narrow, pyramidal form and vibrant, year-round green foliage. This article explores its typical growth patterns, mature dimensions, and environmental factors influencing its development, providing a comprehensive overview for cultivation.
Typical Growth Rate and Mature Size
Emerald Green Arborvitae exhibits a moderate growth rate, typically adding 6 to 12 inches of height annually once established. While initial growth can be faster (1 to 2 feet per year when young), the rate generally settles as the tree matures. This consistent, manageable growth makes it a good choice for many landscape designs.
Mature height generally ranges from 10 to 15 feet, with a narrower width of 3 to 4 feet. This slender profile makes it suitable for privacy screens and hedges where wider plants would be impractical. The species can take 10 to 15 years to reach its full mature height.
Key Factors Influencing Growth
Environmental and care elements impact the growth and overall health of Emerald Green Arborvitae. Adequate sunlight is important; full sun exposure promotes denser foliage. While these trees tolerate partial shade, a minimum of six hours of direct sunlight per day is recommended for optimal growth and to prevent sparse foliage. Too much shade can reduce foliage density, while excessive direct sunlight, especially in warmer climates, may cause foliage burn.
Soil conditions are important for healthy development. Emerald Green Arborvitae prefers consistently moist, well-drained loamy soils with a neutral to alkaline pH, typically 6.0 to 8.0. Although adaptable to various soil types, good drainage is crucial to prevent root rot, as roots can become soggy in waterlogged conditions. Amending heavy or sandy soils with organic matter like compost or peat moss can improve both drainage and nutrient content.
Consistent watering is important, especially during the plant’s establishment phase and in dry periods. These trees are moderately drought-resistant once established, but young plants require regular moisture. Climate and hardiness zones also influence growth; Emerald Green Arborvitae thrives in USDA Zones 3 to 7, with some sources extending this range to Zones 2 to 8.
They tend to perform better in cooler, drier climates, though they can adapt to warmer, more humid conditions with proper air circulation. Nutrient availability in the soil is also a factor. While these trees are low-maintenance regarding fertilization, a balanced, slow-release fertilizer in early spring can support healthy growth, particularly if the soil lacks essential nutrients.
Cultivating Optimal Growth
Proper planting techniques are important for optimal growth. The ideal time for planting is typically in the fall or early spring, as milder temperatures reduce stress during establishment. Digging a hole that is twice as wide as the root ball but no deeper than its height allows roots to spread effectively and prevents the tree from settling too deep. The top of the root ball should be level with or slightly above the surrounding soil surface.
Consistent watering is crucial, particularly for newly planted trees. For the first few months after planting, deep watering two to three times per week is recommended until the tree becomes established. After this initial period, about 1/2 to 1 inch of water per week, either from rainfall or supplemental irrigation, is sufficient. Ensure the soil remains moist but not waterlogged to prevent root issues.
Applying a 2 to 3-inch layer of organic mulch, such as wood chips or bark, around the base of the tree helps retain soil moisture, regulates soil temperature, and suppresses weed growth. Keeping the mulch a few inches away from the trunk helps prevent moisture buildup and potential rot. Regularly removing weeds from the area around the tree’s base minimizes competition for water and nutrients, further supporting healthy development.
Long-Term Expectations and Maintenance
As Emerald Green Arborvitae matures, it maintains its naturally narrow, pyramidal shape, offering a dense and consistent green appearance year-round. Its dense foliage provides an effective screen, and the plant holds its vibrant color even through winter, though some slight bronzing can occur in very cold conditions. The tree’s longevity contributes to its value as a permanent landscape feature.
While Emerald Green Arborvitae requires minimal pruning due to its naturally tidy growth habit, light annual trimming can help maintain its desired shape and density. The best time for pruning is typically in late winter or early spring, just before new growth begins. Avoid cutting into old, bare wood, as this can result in unsightly gaps that may not readily fill in. Removing dead, diseased, or damaged branches promptly is beneficial for the plant’s health and appearance.
Common issues that can affect growth include browning of foliage, which may be caused by drought stress, winter burn, or poor drainage. Ensuring adequate watering, especially during dry spells, and proper soil drainage can mitigate these problems. Protecting young plants from harsh winter winds with burlap can also prevent winter burn.