Arborvitae Care Guide

Arborvitae have a reputation as the easy hedge. Plant a row, walk away, get privacy. That works often enough that people stop paying attention, and then one summer half the row turns brown and nobody knows why.

The plant itself is tough. Thuja occidentalis, the eastern arborvitae, grows wild from Canada down the Appalachians, and the University of Connecticut notes it’s most at home in northern swamps and on cold cliffs. What it can’t handle is a combination of things homeowners do by accident: planting too deep, planting in a wet spot, skipping water in August, and shearing it back to bare stems.

Everything below is pulled from university extension guides (Oregon State, Minnesota, Iowa State, UConn, Kansas State, Penn State, NC State and others) plus nursery spec sheets. I’ll link the main ones as we go.

Step zero: plant the right arborvitae

Most care problems start at the garden center. A variety that wants to be 50 feet tall will not stay 10 feet tall because you asked nicely, and constant cutting to hold it back is what creates bare patches.

Sizes come from the Iowa State cultivar table, Oregon State Extension, NC State’s Green Giant page and Monrovia’s North Pole listing. Sources disagree a little on heights, which is normal for plants. Climate and soil change the final size.

If you’re stuck between the two most popular ones, I compare them in detail in Emerald Green vs Green Giant.

Pick the spot

Sun. UConn says eastern arborvitae need about 8 hours of direct sun for best growth. Oregon State allows some afternoon shade but says more sun is better. In heavy shade the plant goes thin and open, and the Morton Arboretum notes shaded arborvitae develop a dead interior that won’t regrow.

Drainage. This is the big one. Oregon State puts it bluntly: boggy soil will kill arborvitae. Fix drainage before you plant, either by working in organic matter or, in bad cases, with drain tile. Root rot is a real risk in wet ground, and Oregon State’s plant disease handbook lists ‘Smaragd’ (Emerald Green) as the most susceptible of the arborvitae it rated.

Soil pH. Not fussy. UConn lists pH 6.0 to 8.0 as the sweet spot and recommends a soil test before planting.

Salt. Keep them away from heavily salted roads and the end of the driveway where plow spray lands. Minnesota Extension says salt spray and salty runoff both injure evergreens, and NC State lists Green Giant as intolerant of salt.

Air. NC State’s Henderson County office linked shade, dense planting and constantly wet bark to canker problems. Don’t cram them into a corner with no air movement, and don’t let your mower blow clippings into the base. If you use a string trimmer along the row, keep the line off the trunk; my notes on cordless string trimmers cover the guards.

How to plant arborvitae

1. Dig wide, not deep

Make the hole about twice as wide as the root ball (Oregon State). Colorado State goes further and suggests a saucer about three times as wide. Width matters more than depth, because new roots spread sideways into loose soil.

2. Get the depth right

Set the root ball on undisturbed soil so its top sits 1 to 2 inches above the surrounding ground. Planting too deep is one of the most common ways to kill an evergreen slowly. Penn State lists it as a factor in Phytophthora root rot. If you dug too deep, add soil back under the ball and firm it before you set the plant.

3. Deal with the burlap, wire and roots

For balled-and-burlapped plants, Colorado State says to put the tree in the hole first, then remove burlap, wire basket and twine from the top 12 inches or the upper two-thirds of the ball, whichever is more. Whatever is left at the very bottom can stay.

For container plants, look for roots circling the outside. Colorado State suggests shaving the outer 1 to 1.5 inches of the root ball with a knife or saw and cutting off larger circling roots with pruners.

4. Backfill with the soil you dug out

Use the native soil. A small amount of compost is fine, but Colorado State warns that heavily amended backfill (25 to 50 percent organic matter) can hold too much water and keep roots from leaving the hole.

5. Water it in

Soak the hole as you finish so the soil settles around the roots. Check the grade again after it settles and top up if needed.

6. Mulch

Spread 2 to 4 inches of wood chips or shredded bark over the planting area, keeping it pulled back from the trunk. Nebraska Extension adds: no landscape fabric underneath. Minnesota Extension says not to go deeper than about 3 inches on the root area, since thick mulch can block water and cause root problems in wet soil.

7. Stake only if you must

Colorado State says staking is usually unnecessary when the plant sits on firm undisturbed soil. Tall, narrow nursery stock in a very windy spot may need temporary support. Remove it after a season.

Watering: the part that decides everything

New arborvitae have only the roots that came in the pot or burlap, and those dry out fast. Here’s the first-year schedule from Minnesota Extension:

How much each time? Minnesota suggests one-quarter to one-third of the container’s volume for shrubs, so roughly 2 gallons for a 7-gallon pot. Kansas State suggests a weekly soak of about 10 gallons for larger spring- or summer-planted trees and shrubs after the first month, split into two smaller doses on sandy soil.

Skip a watering only after a real rain, more than an inch in a day. A passing shower doesn’t count.

Years two and three. Kansas State says young plants usually need regular watering through their first three growing seasons. Water every 10 to 14 days without rain, soaking 8 to 12 inches deep.

Established hedges. Wisconsin Extension uses about 1 inch of water per week as the baseline for established trees and shrubs, more on sandy soil in severe drought. Oregon State says even established arborvitae need a deep soak every 2 to 3 weeks during dry spells.

How to check. Push a long screwdriver or your finger into the soil near the root ball. Moist a few inches down means wait. Dry means water.

Water slowly. A soaker hose under the mulch works well for a long row. Fast water runs off; slow water sinks in.

Lawn sprinklers aren’t a good substitute. The lawn wants shallow, frequent water and the hedge wants deep, slower soaks. My guide to how often to water a lawn covers the grass side.

Fall watering and winter prep

Drought damage on arborvitae often shows up months later. Oregon State notes it may not appear until fall, and Wisconsin says evergreens that go into winter dry can burn badly by spring.

Minnesota Extension’s fall routine is simple: ease off slightly in September so the plant hardens off, then water thoroughly in October until the ground freezes. They also say watering only in late fall, after a dry summer, doesn’t fix the problem. It has to be steady through the season. Put it on your fall lawn care list so it doesn’t get forgotten.

Winter burn

Winter sun and wind pull water out of the foliage while the roots sit in frozen soil. Minnesota lists arborvitae among the most susceptible evergreens, and new transplants are the most sensitive. Damage shows on the south, southwest and windward sides.

If your plants burned before, put up a burlap screen on those sides in late fall, leaving the top open. Minnesota Extension found anti-desiccant sprays don’t work for this, so I’d skip them.

Snow and ice

Upright arborvitae split under heavy snow. Michigan State names Emerald Green and Green Giant among the columnar types that don’t handle heavy snow or ice well. Oregon State adds that freezing rain is worse than snow because it can bend limbs for good.

The fix is to tie them up for winter. Minnesota suggests strips of cloth, carpet or old nylon stockings wrapped around the plant about two-thirds of the way up. Michigan State uses burlap, which also keeps deer off. The important part: take it all off in spring. Forgotten ties girdle branches.

After a storm, brush wet snow off gently with a broom, pushing upward.

Fertilizing

Arborvitae don’t need much. UConn suggests a soil test first, then fertilizing in early spring if the test calls for it, spread over the whole root zone and ideally before a good rain. Follow the product label for the amount.

Two don’ts from the extension sources: don’t fertilize in late summer, because soft new growth won’t harden off before winter, and don’t fertilize a plant that’s drought stressed. UConn also notes that arborvitae next to a regularly fertilized lawn usually need nothing extra.

Pruning

Arborvitae need very little pruning, and most damage comes from overdoing it.

When. The Morton Arboretum recommends routine shaping in spring around when new growth starts, and heavier work in early spring before growth begins so new shoots hide the cuts. Light touch-ups are fine later in the season. Dead or broken branches can come off any time.

How much. Only cut into green growth. Oregon State and UMass both say arborvitae won’t regrow from bare stems. If you cut back past the green to brown twigs, that spot will stay bare.

Shearing. It’s fine for a formal hedge and makes the outer shell denser. The catch, according to UMass, is that a dense shell shades the inside so the inner needles drop. That’s normal. Just don’t cut into that bare zone. I keep the bottom of a hedge a touch wider than the top so light still reaches the lower branches.

Height. You can top an arborvitae, but it won’t grow a new leader from a bare stub, and the cut top will show for a while. It’s much better to plant a variety that tops out where you want it.

Lost leader. If snow snaps the top, Morton suggests tying a side branch upright to become the new leader. Remove the tie before the next growing season.

For a short row, battery hedge trimmers are plenty. I use EGO tools in my own yard, and my overview of battery yard tool systems covers the platforms.

Deer

Deer love eastern arborvitae. UConn calls it a favorite food, and Iowa State says winter browsing can do severe damage. Oregon State notes deer usually work the bottom 4 to 5 feet, which leaves the classic “lollipop on a stick” look.

Oregon State also says repellents need frequent reapplication and aren’t proven, and that fencing is more reliable. If you have heavy deer pressure, Green Giant is the better pick. UConn says it’s seldom browsed.

Keeping an eye on problems

Arborvitae have few serious pests, but a handful show up often enough to check for twice a year.

Clear out the pile of dead needles inside the base each year too. NC State’s Henderson County office says built-up needles hold moisture against the stems and can invite canker.

I go through each cause and what to do in Why is my arborvitae turning brown?.

Arborvitae care calendar

It slots in nicely alongside the lawn care calendar.

Replacing a dead plant in a row

Oregon State’s advice is to find out why it died before replanting, because the same cause will kill the replacement. Wet soil is the usual suspect. Then buy the largest replacement you can, so it has a chance to catch up with its neighbors.