Tree · Cupressaceae
Emerald Green Arborvitae
Thuja occidentalis
Plant it in full sun with steady moisture, guard it from deer and snow, and it gives you a dense green screen for decades.
Full sun
Every 5–10 days
USDA 3–7
12–14 ft · 3.7–4.3 m
Overview
Emerald Green Arborvitae is the narrow evergreen you see lined up as a living privacy screen across much of the cold north. It's a 'Smaragd' selection of the eastern white cedar, Thuja occidentalis, and it keeps a tight pyramid of bright green foliage all year. The plant tops out around 12 to 14 feet (3.7 to 4.3 m) tall and stays just 3 to 4 feet (91 to 122 cm) wide, which makes it a clean fit for a property line.
Growth is slow and steady rather than fast, so it asks for very little once it settles in. It shrugs off cold down to -40°F (-40°C) and handles a range of soils, even heavy clay, as long as the ground drains. What it won't forgive is drought or a soggy root zone.
The catch is winter and wildlife. Deer treat it as a favorite browse, heavy snow can splay a multi-stem plant open, and a dry, windy site burns the foliage brown. Get the placement and the winter prep right, and the rest is easy hedging for years.
Care
The short version: full sun to light shade, soil kept evenly moist but never waterlogged, and a deep drink in fall before the ground freezes. Shelter it from deer and harsh winter wind, and tie up multi-stem plants ahead of the snow.
Light
Give it full sun for the densest, healthiest growth, though it takes partial shade without much complaint. Too little light thins the foliage and opens gaps in what should be a solid screen.
Water
Keep the soil consistently moist and well drained, watering deeply every 5 to 10 days during dry spells. This plant has no tolerance for drought or dry, windy exposure, so give it a thorough soak in fall before the ground freezes to head off winter desiccation.
Soil
It grows in moist, fertile, well-drained loam and even tolerates clay, as long as water doesn't sit. The pH range is wide, from 6.0 to 8.0, which covers most garden ground from slightly acidic to alkaline.
Temperature
Cold is no obstacle here. The plant survives from -40°F to 100°F (-40°C to 38°C), which is what lets it serve as a hedge across the far north.
Humidity
Average outdoor humidity suits it, so there's no number to manage. Airflow and steady soil moisture matter far more than the air's dampness.
Feeding
Feed once in spring with a balanced, slow-release evergreen fertilizer. A single seasonal application is plenty for a plant that grows this slowly.
Pruning
Keep pruning light, shearing in late spring or early summer to shape a hedge. Never cut back into bare old wood, which won't regrow, and tie up or wrap multi-stem plants before winter so snow and ice can't splay them apart.
Repotting
This is a long-term landscape plant that's rarely repotted. In a container, circling roots at the edge of the root ball, stunted new growth, or water running straight through tell you it has outgrown its pot.
Size & spacing
Expect a mature plant 12 to 14 feet (3.7 to 4.3 m) tall and just 3 to 4 feet (91 to 122 cm) wide. For a solid screen, set plants close enough that the narrow crowns will knit together as they fill in.
When to plant
This is a plant-it-and-leave-it evergreen with no sowing season and no harvest. Set new plants out in spring or early fall so the roots can settle while the soil is warm, and skip planting in the dead of summer heat or hard winter.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: spring or early fall
- Harvest: Non-flowering; grown for evergreen foliage
Hardiness
USDA hardiness zones: 3–7
Temperature: down to -40°C
Troubleshooting
Most arborvitae trouble traces back to winter or to a few familiar pests. Browning foliage, stripped branches, and splayed stems each point to a different cause, so read the signs before you act. Match what you see below and step in early.
Lower branches stripped bare over winter
This is deer browsing, and Emerald Green is one of their favorite winter meals. The damage shows as a ragged line up to about deer height, often with tracks and droppings nearby, and rabbits will work the lowest foliage too. Fence or net young plants before the snow arrives, since hungry deer can hollow out a hedge once other food runs short.
Fix:
- Install fencing or netting around plants
- Apply deer repellents and reapply after rain
- Wrap plants with burlap over winter
Small brown bags dangling from stripped branches
Those little spindle-shaped sacks are bagworms, the worst defoliator this plant faces. Each bag runs 1 to 2 inches long and wears bits of foliage as camouflage, and you'll see them twitch when the larvae feed in early summer. Pick the bags off through fall and winter to clear out next year's eggs, and hit young larvae with Bt in late spring before a heavy run defoliates and kills the plant.
Fix:
- Handpick and destroy bags in fall and winter to remove overwintering eggs
- Apply Bacillus thuringiensis (Bt) to young larvae in late spring or early summer
- Use labeled insecticide for larger infestations
Browning, fading plant standing in soggy ground
When the soil stays waterlogged, root rot sets in and the foliage browns as the plant slides into decline. Dig at the root ball and you'll find dark, soft, mushy roots instead of firm white ones. Improve the drainage, ease off the water, and replant badly hit specimens somewhere the ground drains freely. The surest prevention is to keep this tree out of low spots that pool water.
Fix:
- Improve drainage around the root zone
- Avoid overwatering
- Replace severely affected plants in well-drained sites
Bronzed, dried foliage on the windward side after winter
This is winter burn, the result of dry foliage losing water faster than frozen roots can replace it on exposed, windy sites. It shows up late winter to early spring on the sun and wind side, and while 'Smaragd' holds its color better than the plain species, harsh exposure still scorches it. Water deeply in fall before the ground freezes, screen with burlap where wind is fierce, and prune out the dead brown once new growth returns. A bit of plain winter bronzing is normal and greens back up on its own.
Fix:
- Water deeply in fall before ground freezes
- Wrap or screen with burlap on exposed sites
- Prune out dead brown areas in spring once new growth resumes
Stems splayed open or snapped after a snow load
Heavy snow and ice pry multi-stem plants apart, bending the leaders outward or cracking them. Unwrapped specimens with several trunks take the brunt of it. Brush snow off gently after storms, tie the stems together with soft material, and wrap multi-stem plants before winter. In snowy regions, a single-leader plant holds its shape far better.
Fix:
- Gently brush snow off branches after storms
- Tie stems together with soft material
- Stake or cable weakened leaders
Stippled, yellowing foliage with fine webbing in summer heat
Spider mites move in during hot, dry spells, leaving a fine speckling and faint webbing across the foliage. To confirm them, tap a branch over white paper and watch for tiny crawling specks. Blast the foliage with a strong jet of water, follow with horticultural oil or a miticide if needed, and keep the soil moist, since a stressed plant draws mites in.
Fix:
- Spray foliage with strong water jet to dislodge mites
- Apply horticultural oil or miticide
- Maintain adequate soil moisture to reduce stress
Toxicity
Emerald Green is a low-risk plant for a home with animals. Its foliage carries thujone oils that can mildly upset the stomach if a pet eats a good amount, but most animals leave the bitter leaves alone. The real thing to lock away is any concentrated thuja essential oil, which is far more dangerous than the plant.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · People
Safe for
Birds
Cats Mild
A nibble of foliage usually passes with little fuss, but a cat that eats much can drool, vomit, or go off its food. Cats are the most sensitive of the household pets here, and concentrated thuja essential oil is far more dangerous than the plant itself, so keep any oil products well out of reach.
Dogs Mild
A curious dog that chews the foliage may drool or have an upset stomach for a while, though small tastes rarely cause more than that. The real hazard is the essential oil, never the odd mouthful of clippings.
Horses Mild
The thujone oils in the foliage can irritate a horse's stomach if it grazes the branches, bringing on mild colic or a dull appetite. Most horses leave the bitter foliage alone, so trouble shows up only when little else is on offer.
Rabbits Mild
Rabbits should not be fed arborvitae, since the aromatic oils can unsettle a small digestive system. A stray nibble is unlikely to do harm, but it has no place in their diet.
Livestock Mild
Cattle, goats, and sheep generally pass over the bitter foliage and come to no harm. Eaten in quantity, though, the thujone can mildly upset the gut, so it pays to keep prunings out of the pasture.
People Caution
No part of this tree is meant to be eaten, and the thujone in the foliage can irritate the stomach and skin. Keep children from chewing the leaves, and wear gloves if the sap leaves your skin itchy when you shear a hedge.
Birds Safe
Backyard and wild birds shelter and nest in the dense foliage without trouble, and the plant poses no real risk to them.
Keep clippings and any thuja essential oil products away from pets; the concentrated oil is the main concern.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Arborvitae comes in many shapes, from towering screens to tidy little globes. These are the cultivars worth knowing when you're choosing one for a spot.
'Green Giant'
A much bigger, faster hybrid that climbs 40 to 60 feet at 3 to 4 feet a year and shrugs off the deer and disease that plague deer-favored 'Emerald Green'.
'Techny' (Mission)
A broad, dense pyramid in deep green that keeps its winter color and takes hard cold in stride.
'North Pole'
A very narrow, columnar selection bred for tight vertical screens where space is short.
'Holmstrup'
A slow, compact, narrowly pyramidal cultivar that holds its rich green right through winter.
'Hetz's Midget'
A dwarf globe only about 3 to 4 feet tall and wide, rounded rather than conical.
'Danica'
A compact dwarf globe grown as a small, rounded foundation accent.
How to propagate
Named cultivars like this one are grown from cuttings rather than seed, so the new plants match the parent exactly. Layering is a slower backup if you only need one or two.
Stem cuttingsModerate
Late summer to fall (semi-hardwood) or late winter (hardwood) · 6 to 12 weeks to root
Cuttings are how you keep a named cultivar true to its parent, since seed won't. Take semi-hardwood cuttings in late summer or fall, or hardwood ones in late winter, dip them in rooting hormone to lift your odds, and expect roots in 6 to 12 weeks.
LayeringModerate
Spring · One growing season
You can pin a low branch to the ground in spring and let it root in place over a single growing season. It works, but cuttings remain the standard way to bulk up cultivars.
Myths
Every arborvitae, Emerald Green included, is deer-proof.
Far from it. Emerald Green ranks among the plants deer browse most often and most severely, and they hit it hardest in winter when other food is gone. Only the hybrid 'Green Giant' is genuinely deer-resistant, so plant that one instead where deer pressure runs high.