How Tall Do Emerald Green Arborvitae Grow

If you’re planning a hedge or a standout evergreen in your garden, you’ve probably asked, ‘how tall do emerald green arborvitae grow?’ This popular conifer is a favorite for good reason, offering a classic look with reliable performance. Understanding its ultimate size is the first step to placing it perfectly in your landscape.

Emerald Green Arborvitae, known botanically as Thuja occidentalis ‘Smaragd’, is a cultivar of the native Eastern White Cedar. It’s prized for its vibrant, emerald-green foliage that holds its color beautifully even in winter. Its dense, narrow, pyramidal form gives it a tidy, formal appearance with minimal effort from you.

So, let’s get to the heart of the matter. Under typical growing conditions, an Emerald Green Arborvitae will reach a mature height of 10 to 15 feet tall. Its spread, or width, is much more slender, typically staying within 3 to 4 feet. This makes it an ideal candidate for tight spaces where a tall screen is needed but width is limited.

It’s important to note that ‘mature’ means after 10 to 15 years of growth. This is not a fast-growing tree that shoots up overnight. It has a moderate growth rate, adding about 6 to 9 inches in height per year under good conditions. This manageable pace means less frequent pruning for you and a plant that steadily fills its role without quickly outgrowing its space.

Factors That Influence Their Final Height

While 10-15 feet is the standard range, several factors in your garden can affect how tall your arborvitae will actually get. It’s not just about planting it and forgetting it.

Sunlight: Full sun is best. Six or more hours of direct sun daily promotes the densest growth and helps the plant achieve its full height potential. In too much shade, growth becomes spindly and slow.
Soil Quality: They prefer moist, well-drained soil. Poor, compacted, or constantly soggy soil will stunt growth and can lead to root rot, preventing the tree from ever reaching a healthy size.
Climate Zone: Hardy in USDA zones 3-7, they thrive in cooler regions. In the hotter end of their range (zone 7), growth might be slightly slower or the plant may experience more stress, potentially limiting ultimate height.
Spacing and Competition: Planting them too close together or near large trees that compete for water and nutrients will limit their size. Each plant needs its own space to access resources.

Using Their Size in Your Landscape Design

Knowing the mature dimensions is key to smart design. Here’s how to use this information effectively.

Privacy Hedges & Screens: This is their most common use. For a continuous screen, plant them 2 to 3 feet apart, center to center. At this spacing, they will grow together to form a solid, tall green wall. For more individual specimen spacing, 3-4 feet apart is better.
Foundation Planting: Their narrow profile is excellent for framing the corners of a house without overwhelming the structure. Just ensure you plant them at least 3-4 feet from the foundation to allow for air circulation and future growth.
Accent or Specimen Plant: A single Emerald Green makes a elegant focal point in a garden bed, especially when contrasted with rounder shrubs or colorful perennials.
Windbreaks: In a row, they can provide a effective windbreak for a patio or smaller garden area.

Planting for Success: A Step-by-Step Guide

To give your arborvitae the best start and ensure it reaches its healthy potential height, follow these steps.

Choose the Right Spot: Select a location with full sun to partial shade and enough horizontal space for its mature 4-foot width.
Dig a Proper Hole: Dig a hole two to three times as wide as the root ball, but no deeper. The top of the root ball should be level with or slightly above the surrounding soil to prevent settling and water pooling around the trunk.
Prepare the Root Ball: Gently loosen any circling roots on the outside of the ball. If it’s container-grown, you can tease the roots apart slightly.
Amend and Backfill: Mix some compost into the native soil you removed. Place the plant in the hole and backfill with your soil mix, tamping gently to remove large air pockets.
Water Deeply: Create a shallow berm of soil around the planting hole to form a water basin. Soak the area thoroughly immediately after planting.
Mulch: Apply 2-3 inches of organic mulch, like shredded bark, around the base. Keep the mulch a few inches away from the trunk itself to prevent moisture and pest issues.

Ongoing Care to Support Healthy Growth

Consistent care in the first few years is crucial for establishment. Once established, these trees are quite low-maintenance.

Watering: Water deeply once a week during the first growing season, especially during dry spells. The goal is to encourage deep root growth. Established trees are somewhat drought-tolerant but will look their best with occasional deep watering during extended dry periods.
Fertilizing: In early spring, you can apply a balanced, slow-release fertilizer formulated for evergreens. Avoid fertilizing in late summer or fall, as this can promote new growth that won’t harden off before winter.
Pruning: Emerald Greens rarely need heavy pruning. The best time to prune is in early spring before new growth starts. If you need to shape them or control height, you can also do a light trim in early to mid-summer. Never cut back into old, brown wood, as it may not regenerate new green growth.

Common Problems That Can Stunt Growth

Even with good care, sometimes problems arise. Being proactive is the best defense.

Bagworms: These pests create small cone-shaped bags on the branches and can defoliate a tree if left unchecked. Hand-pick bags in winter or use an appropriate insecticide in early summer when the larvae are small.
Spider Mites: Cause foliage to look dusty or bronzed. A strong spray of water from a hose can dislodge them, or use a miticide if the infestation is severe.
Root Rot: Caused by poorly drained soil. Symptoms include discolored, wilting foliage and stunted growth. Prevention through proper site selection and drainage is key, as there is no cure.
Winter Burn: In exposed, windy sites, foliage can dry out and turn brown in winter. Anti-desiccant sprays can help, as can planting in a more sheltered location or providing a burlap screen.

FAQ: Your Questions Answered

How fast do Emerald Green Arborvitae grow per year?
They have a moderate growth rate, typically adding 6 to 9 inches in height and 2-3 inches in width each year under ideal conditions.

Can I keep them shorter than 15 feet?
Yes, you can. By pruning the central leader (the top vertical shoot), you can control the ultimate height. However, this requires annual attention, as the tree will continually try to regain its natural form.

What’s the best time of year to plant them?
Early fall is ideal, giving the roots time to establish before winter. Spring is also excellent, as long as you can provide consistent watering through the first summer.

How close to a fence can I plant Emerald Green Arborvitae?
Given their mature width of 3-4 feet, plant the center of the tree at least 2 feet from a fence line. This allows for some growth on the backside and ensures good air circulation, which is vital for preventing disease.

Do they have invasive roots?
No, their root systems are relatively compact and fibrous. They are not known to damage foundations or sidewalks like some large tree species can, making them very safe for planting near structures.

Choosing Emerald Green Arborvitae for your garden is a decision that pays off for decades. By understanding their growth potential and providing simple, consistent care, you’ll be rewarded with a beautiful, structural evergreen that provides privacy, color, and elegance throughout the year. Remember, the key to their impressive heights starts with giving them a strong foundation and the right space to thrive.