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Emerald Arborvitae
Thuja occidentalis ‘Smaragd’
Description & Overview
Emerald Arborvitae is an iconic, versatile plant in the landscape with its compact, narrow to pyramidal form. Flat sprays of lustrous green foliage retain their color in colder winter months, adding four-season interest. Growing to heights of 20 to 25 feet with a spread of about 3 to 5 feet, and boasting low maintenance and adaptability, Emerald Arborvitae is a popular and reliable choice for most locations. Emerald Arborvitae is a cultivar of Northern White Cedar (Thuja occidentalis), a Wisconsin native conifer.
Core Characteristics
Suggested Uses:
For the best growth, Emerald Arborvitae should be planted in full sun in well-draining soils. Although it can tolerate part shade, growth will be dramatically diminished and the foliage will become less dense. Heavy clay soils are not detrimental to the plants; however, light and loamy soil allow the roots to spread and take up plenty of nutrients and water. Arborvitae prefers soils that are neutral to alkaline – perfect for southeastern Wisconsin.
Do you have a fence that isn’t quite tall enough to give you the privacy you need? If installing a new fence is out of your budget, not your style, or simply not allowed by your municipality, Emerald Arborvitae is the answer. Narrow in habit, it won’t take up too much space in the landscape, and as a bonus, the soft, emerald green foliage is refined and modest in the landscape, and not likely to offend the neighbors. Learn more about Green Screens: Living Privacy Fence with Evergreens.
More than a privacy screen, Emerald Arborvitae is a great barrier against wind and sound. Plant a row as a windbreak or block the view and noise of a busy road/highway. Not only will a row of Emeralds muffle the sound with its lush foliage, but it will add wonderful color and texture to your yard. Want to block the sight of your boring utility box, shed, or compost? Emerald Arborvitae can do that too!
If you’re a creative person that enjoys expressing yourself through topiary, you’re in luck because Emerald Arborvitae handles shearing and pruning very well. Want a dolphin, star, or football in your yard? Sheer away!
Salable 5-foot B&B Emerald Arborvitae | Pictures early May.
Salable 6-foot B&B Emerald Arborvitae | Pictures early September.
Salable 7-foot B&B Emerald Arborvitae | Pictures early September.
Wildlife Value:
A cultivar of the native Northern White Cedar, Emerald Arborvitae supports quite a few creatures. While it may not be as beneficial as the native, it does have its merits.
Deer, Snowshoe Hares, and porcupines will heavily browse the foliage, which you may or may not want. If your goal is to feed wildlife, this is a great option. If it’s not, well, there are less palatable choices such as a Star Power™ Juniper.
Carpenter ants are an associated ‘pest’ for Arborvitae but attract insectivorous birds such as Pileated Woodpeckers, Downy Woodpeckers, Hairy Woodpeckers, Red-bellied Woodpeckers, Golden-crowned Kinglets, Blackburnian Warblers, Ovenbirds, Northern Parulas, Yellow-bellied Flycatchers, Winter Wrens, and White-throated Sparrows who enjoy ants as a snack. Supporting our declining songbird population is a good thing.
Arborvitae, in general, is a host plant for many different insects including the Arborvitae Leafminer moth (Argyresthia thuiella), Brown Angle Shades (Phlogophora periculosa), Chain-dotted Geometer (Cingilia catenaria), Curved-lined Angle (Digrammia continuata), Evergreen Bagworm moth (Thyridopteryx ephemeraeformis), Juniper Geometer (Patalene olyzonaria), Large Maple Spanworm moth (Prochoerodes lineola), Pale Beauty (Campaea perlata), Pine Measuringworm moth (Hypagyrtis piniata), Cranberry Spanworm moth (Ematurga amitaria), the Joker (Feralia jocosa), and the Variegated Midget (Elaphria versicolor).
The dense foliage provides birds and other animals with cover, habitat, and nesting locations.
Maintenance Tips:
Emerald Arborvitae is easy to grow and low-maintenance. Emerald Arborvitae, and Thuja occidentalis, are tolerant of drought once they are established. It is important to deeply water newly planted Arborvitae to help the roots anchor and stay healthy. Adding mulch around the base of your planting will reduce plant stress and retain soil moisture.
Arborvitae handles pruning and shearing like a champ, but pruning is typically not necessary as they hold their shape well. In those instances where pruning is a must, only trim back the new growth of the current season and remove dieback. Any shearing should be done in early spring before the first flush of new growth.
You shouldn’t need to fertilize your tree, but you can do so before new growth pushes in spring.
Contrary to popular belief, wrapping evergreens in winter is not needed and can hold ice and snow against the needles far longer, causing winter burn and damage. Emerald Arborvitae is hardy and cold-tolerant to Zone 3 (most of Wisconsin is Zone 5).
Pests/Problems:
Black Walnut Tolerant: No
Deer Resistant: No
Rabbit Resistant: No
Deer love to eat Arborvitae. Those soft needles are like candy to our leggy friends. If you have heavy deer pressure in your area you may want to go with a less palatable option such as a spikier juniper. If you’ve only an occasional snackortunist, you can either accept the nibbling or try using deer fencing or deterrent sprays like Bobbex. Read more about Deer Protection, Buck Rub & Resistant Plants.
Ensuring your trees are not stressed (proper siting and water application) is also important so the plant has the strength to combat being browsed upon. Note that flooding or higher-than-normal water levels will reduce growth and may eventually kill trees.
Emerald Arborvitae has few issues with pests or diseases. Bagworm larvae may sometimes happen, but they can be difficult to spot until they’ve already formed their bags and begun chewing. Inspect your trees in the fall when eggs are laid, and again in May through June when they hatch. The least damaging removal method is hand-picking or cutting the bags from the plants. If this is too difficult (and gross), contact an arborist for assistance.
Spider mites are the other pest that can afflict Arborvitae. They are incredibly tiny and tough to see with the naked eye. An indicator that there is a problem is that foliage begins to turn a dull green. Mites are difficult to treat and require multiple applications of a targeted product to avoid harming beneficial insects. We recommend contacting an arborist for assistance.
The best prevention is appropriate care. Make sure your Arborvitae are watered properly and a bark mulch ring is applied around the base of the tree to help reduce moisture loss and protect the roots in winter.
Leaf Lore:
The genus name Thuja is Greek for “a kind of juniper,” while the specific epithet occidentalis means “from the Western (Occidental) world.” The cultivar name ‘Smaragd’ is Danish for “Emerald.”
Emerald Arborvitae originated as a seedling selected in 1950 by D.T. Poulsen Nursery in Kvistgaard, Denmark.
The mother plant, Northern White Cedar (Thuja occidentalis) reaches ages over 800 years.
Thuja occidentalis in general was used by several Indigenous tribes for many purposes. Arborvitae foliage is rich in vitamin C and was used to treat scurvy. All parts of Northern White Cedar as a cough syrup, a deodorant, a disinfectant to fumigate for smallpox, to treat headaches, and as a smudge to revive unconscious people. Wood was made into canoe ribs, fishing spears, and toboggans, and bark was used for weaving bags.
Leaves have been used in steam baths to treat rheumatism, arthritis, and colds.
Companion Plants:
Adding biodiversity to your green screen is important to avoid a mass wipeout (think ash trees) and will add lovely texture and color. Combine Emerald Arborvitae with Taylor Juniper, Mountbatten Juniper, Eastern Red Cedar, Iowa Juniper, Burkii Juniper, Star Power™ Juniper, Cypress Spruce, White Spruce, Norway Spruce, Eastern White Pine, Degroot’s Spire Arborvitae, Holmstrup Arborvitae, Pyramidal Arborvitae, Wintergreen Arborvitae, or Green Giant Western Arborvitae.
Use Emerald Arborvitae as a backdrop to colorful plants such as Redosier Dogwood, Royal Raindrops Crabapple, Glossy Black Chokeberry, Dwarf Bushhoneysuckle, St. John’s Wort, Center Glow Ninebark, American Filbert, or Common Winterberry.
