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Arborvitae’s struggles highlight advantages of choosing native plants

By Julie Banken
WSU Chelan/Douglas County Master Gardener

August 25, 2025

Deer browsing, summer heat, and winter scorch took their toll on this moisture-loving arborvitae hedge. Pruning to remove dead foliage and branches creates a new look, and soon, better-adapted native plants will fill the empty space. – Provided photo/Julie Banken

Julie Banken – WSU Master Gardener intern – Provided photo/WSU Master Gardeners

When my family bought our home almost 25 years ago, a friend made a prophetic comment. “Good luck with that hedge,” he said.

In retrospect, “that hedge” was probably why no one else bought our house. It was a 90-foot green wall of arborvitae, a considerable responsibility. Arborvitae may be one of the most common landscaping plants sold in nurseries, but it is notoriously difficult to keep healthy in Eastern Washington.

Arborvitae is not a weak plant. It thrives where it grows naturally, in the humid climate of northeastern North America. Like its Western Red Cedar relative, arborvitae trees grow in places such as lakeshores and bog edges, where the ground stays moist year-round. In contrast, Eastern Washington growing conditions are almost the opposite of what arborvitae has evolved to handle, and it is therefore prone to struggle.

Plants adapted to arid regions have strategies to protect themselves from drying out. When summer temperatures are high and humidity is low, a significant amount of water can escape through tiny holes in their leaves called stomata. Our native plants can quickly close these holes, trading the opportunity to photosynthesize for the safety of staying hydrated.

Moisture-loving arborvitae trees, meanwhile, are less efficient at conserving water. Open stomata are advantageous on the East Coast where the air is humid and the ground gets 30 to 50 inches of precipitation per year, but here our air is dry and windy, and our rainfall is a fraction of that. Arborvitae’s stomata close more slowly and less tightly and can easily dry out without continuous irrigation.

Even in winter, arborvitae bushes can get too dry. Arborvitae don’t mind the cold as long as their shallow roots have access to water. They are adapted to spending winters insulated by deep snow, but here snowfall is unpredictable. If the ground is bare, it can freeze solid, and water will be locked up as ice. On sunny winter days, roots can’t replace moisture lost through their leaves, and plants will dry out. In spring, leaf tips will turn brown, and branches will show signs of winter scorch.

Arborvitae that manage to stay hydrated in the dry climate of Eastern Washington still have to survive another danger: deer. They are a food source for deer in their native habitat, so it should be no surprise that deer love them here, too. There are other cypress relatives that are more deer-resistant, but a hedge of the most common species, Thuja occidentalis, is practically a free buffet to hungry browsers in the winter.

Unfortunately, once the leaves have turned brown or are eaten off an arborvitae’s branches, they will not grow back. You can cut a lilac down to the ground and it will sprout up again, but the gangly branches on an arborvitae have no buds. Bare patches in a hedge are frustratingly permanent.

These popular evergreen plants also come with a hidden danger. Their waxy foliage is so dense, new leaves block light to the ones below them, and without sunlight, they can’t photosynthesize. Old leaves will die and drop off. Arborvitae bushes that manage to stay leafy green on the outside can hide a flammable thicket of dry branches and dead leaves on the inside.

Because they collect so much debris in their branches, even a healthy arborvitae can quickly go up in flames during an Eastern Washington wildfire. Kamloops, B.C., recognizes the hazard of having these plants close to a home in a fire-prone region. They offer free chipping services and will even pay residents to remove arborvitae shrubs that are planted within 16 feet of a structure.

My colossal hedge is on its last legs now. I will not miss trimming it while standing on a 14-foot orchard ladder or wrestling with black nylon deer fencing each year, but I will miss the green wall of privacy it has provided. Given that arborvitae was never meant to grow here in the first place, I give it credit for surviving as long as it has.

Sadly, record summer heat, relentless wind, and sudden sub-zero freezes have taken their toll. Someday soon, I will replace it with a native hedge, one already adapted to life in our arid climate.

A WSU Chelan-Douglas County Master Gardener column appears weekly in The Wenatchee World. To learn more, visit bit.ly/MGchelandouglas or call (509) 667-6540.