CORVALLIS, Ore. — For a hedge, arborvitae has its place. It’s tall, narrow, evergreen, low maintenance and inexpensive.
“Some people look down on arborvitae, but it fits in places where other plants can’t. And it’s about as low maintenance a plant as you can buy, if it’s sited correctly.”
“Some people look down on arborvitae, but it fits in places where other plants can’t,” said Neil Bell, a retired horticulturist with the Oregon State University Extension Service. “And it’s about as low maintenance a plant as you can buy, if it’s sited correctly.”
When choosing a location, Bell recommends full sun and well-drained soil.
“They can take some afternoon shade,” he said. “But when I say afternoon shade, I mean after 3 p.m. The more sun, the better. Otherwise, the foliage will suffer.”
If your soil is boggy, arborvitae won’t survive. Bell suggests correcting drainage problems before planting. Digging in organic material may help, but in serious cases you may need to install drainage tiles.
“You’ve got to have good drainage,” he said. “If there’s standing water, it’s one of the few situations where they will not thrive.”
Hot, dry summers can also cause problems. During recent droughts, many arborvitae showed dieback. Even though people often think established trees don’t need watering, Bell advises soaking them every two to three weeks during dry spells.
“Even if plants are established, they need water,” he said. “They may not wilt right away, but you’ll see damage in fall. They’ll turn brown. If you prune out the damaged tissue and water the next summer, they may recover.”
Planting and growth
Unlike laurel hedges, arborvitae do not produce new growth if cut back to bare stems. Avoid hard pruning, but light pruning any time of year is fine if needed to maintain shape.
“If they are well sited, planted properly and get enough sunlight, they will form a natural vertical green fence by themselves,” Bell said.
The most common hedge arborvitae in the Pacific Northwest is ‘Emerald Green.' At maturity it typically grows about 12 to 15 feet tall and 3 to 4 feet wide, making it a good fit for small urban lots.
Another popular choice is ‘Green Giant’, a vigorous hybrid often used for tall privacy screens. It commonly reaches 40 to 60 feet tall and 12 to 18 feet wide at maturity, so it’s best for larger spaces. For context, the species Thuja occidentalis can grow to about 40 feet in landscape settings, though it may grow taller in the wild.
Plant arborvitae like any other tree. Dig a hole twice as wide as the root ball and just deep enough so the top sits 1 to 2 inches above ground. A helpful resource is Selecting, planting and caring for a new tree from OSU Extension. Space trees 3 to 4 feet apart.
Winter, pests and deer
Some cultivars turn a washed-out brown in winter, though ‘Emerald Green’ typically does not. Winter browning usually affects all the foliage, while drought stress appears sporadically on individual trees in a hedge.
Arborvitae have few pest problems. Mites are uncommon but may appear, leaving a grayish cast on foliage.
Deer browsing is more common in Eastern Oregon, but deer in Western Oregon will also eat arborvitae when they find it. Deer usually feed on the bottom 4 to 5 feet of the plant. Repellents require frequent reapplication and aren’t proven effective. Fencing is a more reliable solution.
If your area receives snow, tie up the tops of arborvitae to prevent splitting. “Freezing rain is worse than snow,” Bell said. “It tends to peel them apart, and once the limbs are bent over they will stay bent.”
When replacing
If a tree dies, first determine the cause before replanting. Choose the largest replacement you can find so it catches up to neighboring trees. For help diagnosing problems, contact the Extension Master Gardeners in your county.
The bottom line, Bell said, is that arborvitae planted in full sun with good drainage will perform well for many years.
Previously titled Arborvitae stands tall as easy-care hedge
