Trim Emerald Green arborvitae lightly once a year, in late spring after the new growth has flushed, with an optional touch-up in early summer. Cut only within the green, leafy foliage and never back into the brown interior, because arborvitae does not sprout new growth from bare wood. In New England, much of keeping them looking good actually happens in winter: tying stems against snow splay, watering before the ground freezes, and protecting them from deer.
Emerald Green is one of the most common screening plants in North Shore yards, and it is easy to keep handsome once you know its few rules. Zacarias Tree & Landscaping, a family-run tree and landscape company based in Lynn, trims, plants, and replaces arborvitae hedges across Essex and Middlesex Counties, and this is how we approach them.
Know the plant you have
Emerald Green, sometimes sold under its cultivar name 'Smaragd', is a narrow, slow-growing form of eastern arborvitae. It typically matures somewhere around 10 to 15 feet tall and only 3 to 4 feet wide, which is why it is so popular along property lines. It is cold hardy well beyond anything our winters bring; you can confirm your own zone on the USDA Plant Hardiness Zone Map.
It is often confused with Green Giant arborvitae, a different, much larger hybrid that can grow several feet a year and reach heights many times that of Emerald Green. If you are constantly fighting to hold a hedge down, check the plant tag: you may have Green Giant, and no amount of trimming will turn it into a narrow screen.
When to trim
- Main trim: late spring, once the season's first flush of soft new growth has appeared. Cuts are hidden quickly by the growth that follows.
- Touch-up: early summer, if you want a crisper shape.
- Avoid: late summer and fall. New growth triggered late in the season does not harden off before winter and is easily damaged by cold and wind.
- Any time: remove dead, broken, or snow-damaged branches as you find them.
How to trim Emerald Green arborvitae, step by step
- Use the right tools. Sharp hand pruners for individual cuts and clean hedge shears for light shaping. Dull blades crush foliage and leave brown edges.
- Shape wider at the bottom. Keep the base slightly broader than the top, so sunlight reaches the lower branches. A hedge that is wider at the top shades itself out and goes bare at the bottom.
- Take a little, from the outside. Trim back only the current year's growth, a few inches at most. Step back often to check the shape.
- Stay in the green. Before each cut, part the foliage and look. If there is no green growth below where you plan to cut, do not cut there.
- Handle the top carefully. You can cut the central leader to hold height, but the top will flatten and may send up several new shoots. If height is the real problem, the plant is probably the wrong size for the spot.
The bare-wood rule
The inside of an arborvitae is naturally brown. Needles there get little light and drop off over time, which leaves bare stems covered only by the green outer shell. Cut into that zone and the plant will not fill the hole back in; you will see a brown patch for years. It is also normal for older interior foliage to turn brown and shed each fall. That seasonal browning on the inside is not a disease, and you can gently shake or brush it out.
Snow splay and ice
Emerald Green often grows with several upright stems. Heavy wet snow, common in nor'easters, pushes those stems apart and can leave the plant permanently splayed open. To prevent it:
- In late fall, loosely spiral soft, wide tree strapping or garden ties around the plant from bottom to top, snug enough to hold stems together but not tight enough to cut into bark.
- Remove the ties in spring so they do not girdle growing stems.
- After a snowfall, brush snow off with a broom using gentle upward strokes.
- After an ice storm, leave the ice alone. Knocking it off frozen branches breaks them. Let it melt, then tie back any stems that were pushed out.
Winter burn and salt
Winter burn shows up in late winter or early spring as brown or bronze foliage, usually on the side facing the sun or the wind. It happens when needles lose moisture on bright, windy days while the ground is frozen and roots cannot replace it. Plants near the coast, and those beside salted roads and driveways, get hit harder.
- Water deeply in fall until the ground freezes, especially after a dry summer.
- Keep 2 to 3 inches of mulch over the root zone, pulled back from the trunks.
- For exposed spots, set a burlap screen on stakes a little away from the plants rather than wrapping them tightly.
- Do not rush to cut burned foliage. Wait for spring growth; buds under the brown surface often survive and green up.
Deer
Deer browse arborvitae heavily in winter, often leaving a bare band up to the height they can reach. Netting or temporary fencing from late fall through early spring is the most reliable protection. Once lower foliage is browsed to bare wood, it rarely fills back in, so prevention matters more than repair.
Frequently asked questions
Can you cut the top off Emerald Green arborvitae?
Yes, you can cut the leader to limit height, but expect a flat top and several new shoots competing to take over. It works best as light, regular maintenance rather than one heavy cut.
How much can I trim off an arborvitae?
Only the green outer growth, usually a few inches of the current year's growth at a time. Never cut back past the last green foliage on a branch.
Why is my arborvitae brown inside?
Interior browning, especially in fall, is normal needle shed. Browning on the outside, on the sunny or windy side, is more likely winter burn, salt, or dry soil.
Is Green Giant the same as Emerald Green arborvitae?
No. Green Giant is a separate hybrid that grows much faster and far larger. Emerald Green stays narrow and moderate in height.
When the hedge needs more than shears
If a row has splayed, gone bare at the bottom, or outgrown its spot, our tree trimming and pruning crews can reshape what can be saved, and our planting and mulch installation team can replace plants that cannot. For taller screening trees like Leyland cypress, see our guide to cutting back Leyland cypress. Request a free estimate, usually scheduled the same day.