The Emerald Green Arborvitae (Thuja occidentalis ‘Smaragd’) is an evergreen known for its naturally narrow, columnar habit and year-round foliage. This cultivar is widely used to create dense privacy screens and landscape accents due to its uniform growth pattern. Providing correct foundational care maximizes its longevity and helps maintain its deep green color and compact form.
Establishing Your Arborvitae
Successful establishment begins with selecting the right location, which should receive full sun exposure, ideally six or more hours of direct sunlight daily, though partial shade is acceptable in hotter climates. The plant prefers well-drained soil, as the root zone should be moist but not waterlogged. Heavy clay or overly compacted soil should be amended to prevent issues like root rot.
When planting, dig a hole two to three times wider than the root ball but no deeper. The top of the root ball must be positioned level with or slightly above the surrounding soil grade to ensure the root flare is exposed. Backfill the hole with the original soil, tamping gently to remove air pockets, and water thoroughly to settle the soil. Apply a two to three-inch layer of organic mulch around the base, keeping it several inches away from the trunk.
Managing Water and Nutrients
Consistent, deep watering is essential, especially during the first two growing seasons after planting. Newly planted arborvitae require regular deep soaking to encourage root establishment, often needing water two to three times per week during the first few months. The goal is to moisten the entire depth of the root ball without leaving the soil perpetually saturated.
Check the soil moisture by inserting your finger about two inches deep near the root zone. If the soil feels dry, water; if it feels wet or soggy, hold off on irrigation. Overwatering is a common cause of decline, as it can lead to fungal diseases like root rot that damage the plant’s ability to absorb nutrients. Once established, the arborvitae becomes more drought-tolerant but still benefits from deep, infrequent watering during extended dry periods.
Emerald Green Arborvitae do not typically require heavy or frequent fertilization if the soil is healthy. If new growth is sparse, a light application of a balanced, slow-release fertilizer formulated for evergreens can be applied in early spring. Avoid fertilizing late in the growing season (after mid-summer), as this encourages tender new growth vulnerable to autumn frost damage. Always follow the product’s instructions, as over-fertilization can burn the roots.
Seasonal Shaping and Protection
The Emerald Green Arborvitae’s narrow pyramidal shape means it rarely requires significant pruning for aesthetic maintenance. Any necessary trimming should be light, focusing on shaping or removing dead, diseased, or broken branches. Pruning should only be done on the green, leafy growth. Avoid cutting into the old, brown, leafless wood, as this species will not regenerate new growth from that area.
Protecting the plant during winter is important, particularly in regions with heavy snow or high winds. Winter desiccation, or “winter burn,” occurs when the evergreen foliage loses moisture to dry, cold winds while the ground is frozen, preventing the roots from replacing water. Ensuring the tree is well-hydrated before the first hard freeze (winter watering) is a primary defense against this browning.
Heavy ice and snow accumulation can cause the columnar branches to splay outward or break. To prevent structural damage, gently tie the plant’s branches together vertically with soft twine or specialized tree wrap in late autumn. This technique keeps the plant’s profile tight and allows heavy precipitation to slide off, protecting the upright form of the arborvitae until the snow season passes.