When to Trim Cedar Hedges in Canada (and When to Leave Them Alone)

The best time to trim a cedar hedge in Canada is early spring, before the new growth starts. A second light trim in mid-summer keeps it tidy. Don't trim cedars in the fall. Fall-pruned evergreens get hurt more by winter. So if you're reading this in October, put the shears away and plan a spring trim instead.

What is the best time of year to trim cedar hedges?

Early spring wins. Iowa State University Extension says to prune evergreen shrubs in late March or early April, before new growth begins. Penn State Extension agrees. It says sheared hedges should be pruned in early spring.

Why then? The hedge is about to push out fresh green shoots. Those shoots fill in around your cuts. By early summer, the hedge looks full again, not chopped.

Those dates come from Iowa. Spring shows up at different times across Canada. So watch the hedge, not the calendar. The sign you want is simple: trim before the new soft, bright green growth starts. In colder places, that day comes later in spring.

Can you trim a cedar hedge in summer?

Yes, lightly. Iowa State says light pruning may also be done in mid-summer. Penn State calls a summer trim optional.

A summer trim is a touch-up, not a big cut. It cleans up the new shoots that stick out after the spring flush. Keep it to the soft, green tips.

Some hedges need more than two trims. Iowa State says most hedges need pruning 2 to 4 times, or more, during the growing season to stay sharp. That's normal for a formal, flat-sided hedge. A looser, natural cedar row can get by with less.

Why shouldn't you trim cedars in the fall?

This is the big one for October. Iowa State says to avoid pruning evergreen shrubs in the fall, because fall-pruned evergreens are more likely to get winter injury.

The University of Arkansas Extension gives two more reasons:

• It looks chopped all winter. Fresh cuts won't fill in until spring.
• Late growth is weak. A fall trim can trigger new shoots that aren't hardy enough for the cold.

Canadian winters are hard on those soft shoots. So the fall job for your cedars is easy: leave them alone. Rake the fallen leaves out from under them instead. Our fall lawn cleanup checklist covers that and the other jobs to finish before snow.

Do nesting birds change when you can trim?

They do. Dense cedar hedges are a favourite place for birds to nest. Environment and Climate Change Canada says the general nesting period can start as early as mid-March and run until late August.

The federal rules are clear. Migratory birds are protected at all times. Their nests are protected when they hold a live bird or an egg that can still hatch.

That overlaps with both the spring and summer trim. Here's how to handle it:

• Trim early in spring. Canada's guidance says to use caution at the start of the nesting period. An early trim beats a late one.
• Look before you cut. Walk slowly along the hedge. Watch for birds flying in and out of the same spot.
• Skip any active nest. Leave that section for later in the season, once the birds are gone.

How much can you cut off a cedar hedge?

Less than you think. Cedars don't grow back like a lilac or a privet. Penn State says cutting back to brown wood won't make that branch grow again. Yews are the exception, not cedars.

So stay in the green. Arkansas Extension says to try to keep green foliage on every branch you cut. It also says not to remove more than one third of the plant at once.

Here's what that means with shears in your hand:

• Cut only the newest, soft growth on the outside.
• Stop as soon as you see brown, bare stems inside.
• Take a little each time instead of a lot once a year.
• Step back every few metres and check the line.

A bare brown patch on a cedar can stay bare for years. That's why a careful hand matters more than speed.

What shape should a cedar hedge be?

A little wider at the bottom than the top. Penn State says hedges should take on an inverted "V" shape, so sunlight reaches the lower branches. Iowa State says this shape lets the lower leaves get the sun they need for a full hedge from top to bottom.

Most thin, bare-bottomed cedar hedges have the same problem. They're wider at the top. The top shades the bottom, and the bottom thins out.

You don't need a big slope. A slight lean in on each side is plenty. Pull a string line along the top if you want it dead level.

Clean edges help too. If your hedge borders the lawn, a crisp line along the base looks sharp. That's part of what trimming and edging covers.

Can you cut the top off a tall cedar hedge?

You can, but go slow. University of Maine Extension says the top of an arborvitae won't regrow once it's removed. Arborvitae is another name for the cedars used in hedges.

UMaine also warns that taking too much at once can leave dead spots on top and hurt the plant. Its advice for a big height cut is to spread it over 2 to 3 years. That gives the plants time to adjust.

Here's another reason to keep up with it. The Ontario government says eastern white cedar can reach 15 metres (about 50 feet) high. It's slow-growing, but it doesn't stop. A hedge that gets a light trim every year never needs a drastic cut.

Very tall hedges that need a big ladder aren't a job for a lawn crew. Our partner crews trim what they can reach from the ground or a short step ladder.

Why do cedar hedges turn brown?

Trimming is only one cause. Ontario's page on eastern white cedar says it grows best in moist soil and does not tolerate road salt. It does handle some shade.

So check where the brown shows up:

• Along the street or driveway. Salty snow piled on the hedge all winter can be the cause.
• On the inside, deep in the hedge. Older inner foliage often browns as it gets shaded out.
• Right where you cut last time. That may be a cut into bare wood that won't regrow.

Pests or disease can play a part too. Our partner crews don't spray, and Golden Oak doesn't give advice on chemicals.

What's a simple yearly plan for a cedar hedge?

When	What to do
Early spring, before new growth	Main trim. Check for nests first.
Mid-summer	Light touch-up of the soft tips. Check for nests again.
Fall	No trimming. Clear leaves from under the hedge.
Winter	Keep salty snow off the hedge when you shovel.

Can a local crew trim your cedar hedge for you?

Yes. Golden Oak Lawn Care matches you with a vetted, insured local crew in your city. They do the work. We stand behind it with the Golden Oak Guarantee.

Your crew can handle hedge and shrub trimming in spring and a light trim in summer. They check for nests first and clean up the clippings. Most people book it with their weekly mowing, so the same crew does both.

We price every yard from satellite images, so no one has to come by. Hedge length and height, gates, slopes and haul-away all change the price.

Want it handled? Get your price in 60 minutes, or call 1-866-904-LAWN.

Cedar Hedge Trimming Questions

Sources: Iowa State pruning times, Iowa State formal hedges, Penn State Extension needled evergreens, University of Arkansas arborvitae, University of Maine arborvitae hedges, Ontario eastern white cedar, ECCC nesting periods, Migratory Birds Regulations FAQ.