Techny Arborvitae vs. Emerald Green

Written by Rebecca Mathews
Updated: January 23, 2023
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Arborvitae trees are evergreen conifers used for landscaping and privacy screens. There are lots of species and cultivars to choose from. Techny Arborvitae and Emerald Green are two of the most popular, but what are the differences? Let’s take a look.

Techny Arborvitae Emerald Green Arborvitae
Height/Spread15 feet by 10 feet15 feet by 7 feet
FoliageEvergreen, partially sheds, flat, scaly and dark green. Skirts the ground.Evergreen. Flat, scaly, and bright green.
ConesSmall ½ inch brown cones.Small brown cones ½ long
FlowersSmall, white, hardly noticeableSmall, white, hardly noticeable
ToxicityToxic to humans, dogs, cats, and horses if chewedToxic to humans, dogs, cats, and horses if chewed
Growing Zones2b-72b-7

What are the Main Differences Between Techny Arborvitae and Emerald Green?

Techny Arborvitae and Emerald Green are very similar evergreen arborvitae trees but there are a few differences. Techny Arborvitae is a naturally occurring variation whereas Emerald Green is a cultivar, but the main difference is their foliage.

Emerald Green has bright green foliage that reaches a maximum of 7 feet wide, whereas Techny has deep green foliage that spreads up to 10 feet. Techny is more of a heavy-based pyramid than Emerald Green and it also drops some foliage in fall.

What are Arborvitae?

Arborvitaes are evergreen conifer trees in the cypress Cupressaceae family and their botanical name is Thuja occidentalis. Techny Arborvitae and Emerald Green are just two of the many thuja species and cultivars that are widely used in landscaping and parks.

They have other common names including American arborvitae, Swamp cedar, Northern white cedar and Eastern white cedar, but they are not actually cedar trees. Cedar trees are a different genus.

Techny Arborvitae vs. Emerald Green: Origins

You may have guessed from the common name that American arborvitae trees are native to North America, but they grow in eastern Canada, too.

Arborvitae trees have been used by humans for thousands of years. The Ojibwe, (traditional Anishinaabe people) who are native to modern-day midwestern United States and southern Canada, used arborvitae trees for shelter and their bark and foliage as medicines. The tree is so important to them that it’s called Grandmother Cedar and forms the north plant of their traditional medicine wheel.

Today arborvitae trees’ potent sap and leaves are harvested for essential oils, used as natural pesticides, and researched for their medicinal properties. This article from the journal Molecules explains why thuja occidentalis’ anti-fungal, anti-bacterial, and anti-microbial oils are so important.

And its name? Well, arborvitae is Latin for “tree of life”, and thuja occidentalis is ancient Greek for “perfume of the west.” It’s called perfume because when their scaly leaves are rubbed, they emit a strong sweet scent.

Emerald Green

Emerald Green Arborvitae is a cultivar that was bred 30 years ago. It’s also known as Smaragd. It’s one of the most popular arborvitae cultivars planted in the States because it’s such a bright shade of green and doesn’t get too tall.

Emerald green arborvitae

Emerald green is a slow-growing tree that produces bright green foliage.

©iStock.com/Aliaksandr Yarmashchuk

Techny Arborvitae

In contrast, Techny Arborvitae is a naturally occurring plant that was found in Mission Gardens in Techny, Illinois, hence its name Techny. It’s loved for its dark green foliage.

Techny Arborvitae vs. Emerald Green: Height and Spread

Some arborvitae trees can reach over 200 feet tall, but Techny and Emerald Green are much shorter.

Emerald Green will reach around 15 feet in height and spread over roughly 7 feet. Techny reaches 15 feet so it’s the same height, but it spreads up to 10 feet wide and skirts the ground.

How Fast Do Techny Arborvitae and Emerald Green Grow?

Emerald Green is a slow grower that only puts on nine inches a year after it’s established. Getting established can take several years, so it’s a good choice for containers and short hedging.

In contrast, Techny grows faster. It can put on up to two feet a year so it’s a better choice for fast-growing privacy screens.

Techny Arborvitae vs. Emerald Green: Foliage

Techny Arborvitae and Emerald Green both have evergreen scaly foliage. In both species, this foliage is dense and almost impossible to peek through. This makes them good for privacy screens and a haven for wildlife, including squirrels, birds, and insects.

They also have a dislike of salt sprays in common. In general, arborvitae trees don’t like exposed coastal areas because salt-laden wind burns their foliage.

Emerald Green Arborvitae has tough sprays of flat scaly foliage that grows upright. It’s a popular choice for gardens because this foliage remains bright green all year round. Techny’s foliage is also flat, with fan-shaped clusters but it’s softer and a deeper green. It also has a wider base and touches the soil with branches that hang down further than Emerald Green.

Like Emerald Green, Techny doesn’t change color in winter, but it drops some of the previous year’s foliage in early fall. The branches never appear bare because the current year’s foliage remains in place. The dropped foliage makes an excellent mulch.

Do Arborvitae Trees Have Flowers?

Yes, arborvitae trees including Techny and Emerald Green both produce flowers in spring. The flowers are tiny and insignificant though, so you’ll probably only spot them if you’re having a good look.

The flowers are dull because Thuja occidentalis species don’t need pollinators. Instead, they have male and female flowers that are wind-pollinated. That said, you may still see pollinating insects taking an interest in the flowers.

Do Arborvitae Produce Cones?

Cones produced by arborvitae trees like Emerald Green and Techny are not as showy as pine cones and a little disappointing if you’re hoping to get some free holiday decorations. The cones are around half an inch long and have very sparse woody lips. They start out life green and mature to mid-brown by winter.

Growing Zones for Arborvitae

Both Techny Arborvitae and Emerald Green grow in zones 2b to 7. They prefer cooler temperatures and survive down to minus 40 degrees if their roots are well-drained.  

Zones above 7 are too humid for healthy arborvitae where they tend to develop fungal infections because their evergreen foliage is so dense not a great deal of breeze can air them out.

Techny Arborvitae vs. Emerald Green: Sun Exposure

Even though arborvitae trees prefer cooler temperatures, they still need plenty of sunshine (it’s humidity that causes problems).

Techny and Emerald Green do best when they have six hours of sunshine each day. This brings out the best colors, but they can cope with partial shade too. In full shade, their foliage is dull and becomes spindly over time.

Is Arborvitae Toxic to Dogs?

All species of arborvitae foliage are toxic to humans, dogs, cats, and horses. Its potent essential oils cause vomiting, diarrhea, and shortness of breath if it’s chewed on.

Do Deer Eat Techny Arborvitae?

Deer will eat all species and cultivars of arborvitae including Techny and Emerald Green. Herds of deer can actually strip young trees and kill them.

deer

Deer enjoy eating a variety of plants, including Techny and Emerald Green arborvitae.

©Ginger Livingston Sanders/Shutterstock.com

There’s another creature than eats arborvitae too, but it’s much less obvious. It’s called the Juniper Pug Moth. This Lepidoptera species lays eggs on thuja foliage and their caterpillars eat as much as they can before transforming. They don’t deal much damage to arborvitae trees.

Techny Arborvitae vs. Emerald Green: Which is Best?

Because they’re so similar it’s difficult to choose which is best.

In common they are both evergreen, densely foliaged, and reach the same height of 15 feet. The main difference is their foliage. Emerald Green has scaly bright green foliage. whereas Techny has deep green scaly foliage and its branches touch the ground. Techny is also wide at the base.

If you want to grow arborvitae in a container, then Emerald Green is a better choice because it’s a slow grower. Techny grows up to two feet a year but Emerald Green only grows nine inches.

The best one is really down to which suits your space and preference.

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The photo featured at the top of this post is © Sten Porse / CC BY-SA 3.0 – License / Original


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About the Author

Rebecca is a writer at A-Z Animals where her primary focus is on plants and geography. Rebecca has been writing and researching the environment for over 10 years and holds a Master’s Degree from Reading University in Archaeology, which she earned in 2005. A resident of England’s south coast, Rebecca enjoys rehabilitating injured wildlife and visiting Greek islands to support the stray cat population.

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Sources
  1. RHS, Available here: https://www.rhs.org.uk/prevention-protection/potentially-harmful-garden-plants
  2. Royal Botanic Gardens, Available here: https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:263956-1