The Emerald Green Arborvitae (Thuja occidentalis ‘Smaragd’) is a popular evergreen valued for its narrow, pyramidal shape and dense, deep green foliage, making it an ideal choice for privacy screens and hedges. Successfully establishing this cultivar begins with thoughtful preparation and meticulous planting techniques. Following specific steps ensures the tree can establish a robust root system, which is essential for its long-term health and growth. This process requires attention to detail, from selecting the proper location to the final step of mulching.
Site Selection and Pre-Planting Preparation
The location chosen for your Emerald Green Arborvitae directly impacts its ability to thrive. This cultivar performs best when receiving full sun, which is defined as a minimum of six hours of direct sunlight daily, though it can tolerate partial shade. Planting in too much shade can lead to sparse foliage and a less vigorous growth habit.
Proper soil drainage is another determining factor for success, as arborvitae are susceptible to root rot in waterlogged conditions. The ideal ground condition is a moist, well-draining loam, though the plants can adapt to various soil types. If your soil retains water for an extended period, it may be necessary to amend the area with organic material before planting.
If you are planting multiple arborvitae to form a dense screen, careful spacing is necessary to ensure adequate air circulation and prevent competition for resources. For a solid privacy hedge, the recommended distance is typically two to four feet apart, measuring from the center of one tree trunk to the center of the next. Spacing them too closely, such as less than two feet, can compromise the health of the entire hedge as they mature.
The Step-by-Step Planting Process
The planting hole itself should be dug two to three times wider than the root ball, but it must be no deeper than the height of the root ball. Digging a wide hole encourages the roots to spread outward into the surrounding, less-compacted soil, while ensuring the hole is not too deep prevents the tree from settling below the surrounding grade. Planting the tree too deeply is a common error that can suffocate the roots and cause the trunk to rot.
Before placing the arborvitae into the hole, the root ball requires preparation, particularly if it is container-grown. You must gently loosen or “score” any roots that are tightly circling the perimeter, as this encourages them to grow outward into the new soil. If the tree is balled-and-burlapped, all synthetic materials, wires, and any non-degradable burlap must be removed completely. The top of the root ball, where the trunk flares out, should ultimately sit slightly above the surrounding grade after planting.
Once the tree is positioned, backfill the hole using the native soil you excavated, avoiding heavy amendments unless the soil is extremely poor. As you backfill, gently tamp the soil to eliminate large air pockets, which can dry out the roots. The goal is a firm but not overly compacted fill, which can restrict water and nutrient uptake.
Establishing the Plant: Initial Watering and Mulching
Immediately after planting, a deep, thorough watering is necessary to settle the soil around the root ball and eliminate any remaining air gaps. This initial soaking helps reduce the shock of transplanting and ensures the roots have immediate access to moisture. A soaker hose or drip system can deliver this moisture slowly and directly to the root zone, which is more effective than shallow surface watering.
A consistent watering schedule is essential during the first growing season, as the plant works to establish its root system. A general rule is to water deeply two to three times per week, adjusting the frequency based on soil moisture and weather conditions. The soil should remain consistently moist but never soggy, so check the top two to three inches of soil; if it feels dry, it is time to water again. Both drought stress and overwatering can cause the foliage to brown.
Applying an organic mulch layer is also a beneficial step in the establishment process. A two to three-inch layer of shredded bark or wood chips helps conserve soil moisture, regulates soil temperature, and suppresses weed competition. It is important to keep the mulch several inches away from the trunk flare, creating a small ring of bare soil, to prevent moisture buildup that could lead to rot or attract pests.
Ongoing Care and Maintenance
Once the Emerald Green Arborvitae is established, typically after the first year, its maintenance requirements become significantly lower. Established trees are more tolerant of drier spells, though deep watering during extended periods of summer drought is still beneficial. Watering frequency can usually be reduced to every two to three weeks or as needed, depending on rainfall.
Pruning is minimal for this naturally narrow, pyramidal variety, which maintains its shape well without intervention. Any necessary pruning should be light and primarily for aesthetic shaping or to remove dead or damaged branches. Avoid cutting into old wood, as the tree may not regenerate growth from those areas.
Fertilization is not always necessary for arborvitae unless the soil is poor, but if desired, a slow-release, balanced fertilizer can be applied in early spring before new growth begins. In colder climates, winter protection may be beneficial, such as gently tying up the branches with twine to prevent heavy snow loads from splaying or breaking them. Continue to monitor soil moisture and maintain the mulch barrier around the base of the plant.