Arborvitae shrubs need selective trimming of dead branches rather than heavy shearing to maintain their natural shape. If you are wondering how to trim arborvitae shrubs, the key is to work with the plant’s growth habits rather than against them. Many homeowners make the mistake of cutting too much, which leaves bare spots that never fill in. This guide will walk you through the right techniques, tools, and timing to keep your arborvitae healthy and looking great.
Arborvitae are popular for privacy hedges and landscape accents because they grow dense and stay green year-round. But improper trimming can ruin their form and even kill the plant. Let’s start with the basics.
Why Trimming Arborvitae Is Different
Unlike many shrubs, arborvitae do not produce new growth from old wood. If you cut back into brown, leafless branches, those areas will stay bare forever. This is why light, selective trimming is better than aggressive shearing.
Think of arborvitae as having a “green zone” on the outer layer of branches. Only the green parts can sprout new growth. Your goal is to keep that green zone intact while removing what is dead or damaged.
Best Time To Trim Arborvitae Shrubs
Timing matters a lot. The ideal window is late spring to early summer, after the first flush of new growth appears. This gives the plant time to recover before winter.
You can also do light trimming in late summer, but avoid pruning after early fall. Cutting too late can stimulate tender new growth that gets killed by frost.
- Late spring (May to June): Best for major shaping and thinning
- Late summer (August): Good for light touch-ups
- Avoid winter: Frozen branches are brittle and prone to damage
- Avoid early spring: Sap flow is active, and cuts may bleed
Tools You Will Need
Using the right tools makes the job easier and safer for the plant. Sharp, clean cuts heal faster than ragged ones.
- Hand pruners: For small branches up to 1/2 inch thick
- Loppers: For branches up to 1 1/2 inches thick
- Pruning saw: For thick, woody stems
- Hedge shears: Only for light shaping of green tips
- Disinfectant: Rubbing alcohol or bleach solution to clean blades between cuts
- Gloves: Protect your hands from sap and scratches
Always clean your tools before starting. Dirty blades can spread diseases from one plant to another.
How To Trim Arborvitae Shrubs Step By Step
Now we get to the main event. Follow these steps carefully to avoid common mistakes.
Step 1: Assess The Shrub
Stand back and look at the whole plant. Identify dead, diseased, or broken branches. Also look for branches that cross or rub against each other.
Check for signs of pests or disease, like browning tips or sticky residue. Address these issues before trimming.
Step 2: Remove Dead Or Damaged Wood
Start by cutting out all dead branches. Cut them back to the main trunk or to a healthy side branch. Make clean cuts at a slight angle to shed water.
Dead wood is easy to spot—it is brown, brittle, and has no green leaves. Removing it improves air flow and reduces disease risk.
Step 3: Thin Out Crowded Branches
Look for branches that are growing inward toward the center. These can block light and air from reaching the inner foliage. Cut them at their point of origin.
Thinning helps the shrub stay open and healthy. It also reduces wind resistance, which can prevent breakage in storms.
Step 4: Shape The Outer Form
Now trim the outer edges to maintain the desired shape. For a natural look, follow the shrub’s existing form. For a formal hedge, use a string line as a guide.
Make cuts just above a leaf node or a side branch. This encourages bushy growth. Avoid cutting into the brown interior.
Step 5: Limit Shearing
Shearing with hedge trimmers is fast but can cause problems. It removes too much green growth and creates a dense outer shell that blocks light from the inside.
If you must shear, do it lightly and only on the green tips. Never cut back into the brown zone. Better yet, use hand pruners for selective cuts.
Step 6: Clean Up And Monitor
Remove all clippings from around the base. This prevents pests and diseases from overwintering. Water the shrub well after trimming to help it recover.
Check the plant over the next few weeks for signs of stress, like wilting or browning. If you see problems, adjust your watering or check for pests.
Common Mistakes To Avoid
Even experienced gardeners make errors with arborvitae. Here are the biggest ones to watch out for.
- Cutting into brown wood: This leaves permanent bare spots
- Over-shearing: Creates a thick outer shell that kills inner growth
- Trimming too late in fall: New growth won’t harden off before frost
- Using dull tools: Causes ragged cuts that invite disease
- Removing too much at once: Stresses the plant and slows recovery
If you accidently cut into brown wood, don’t panic. Just leave it alone and let the surrounding green growth fill in over time. It may take a season or two.
How To Trim Different Types Of Arborvitae
Not all arborvitae are the same. The technique varies slightly depending on the variety.
Emerald Green Arborvitae
These grow in a narrow, pyramidal shape. They need minimal trimming—mostly just removing dead branches. If you want to control height, cut the central leader back to a side branch.
Do not top them. Topping creates an unnatural look and weakens the structure.
Green Giant Arborvitae
These are fast growers and can reach 60 feet tall. Trim them lightly each year to keep them bushy. Focus on removing lower branches that die from shade.
For height control, cut the leader back in late spring. This encourages branching and a denser form.
Globe Arborvitae
These are rounded shrubs that stay small. They need very little trimming. Just snip off any stray branches that break the round shape.
Shearing globe arborvitae is common, but do it lightly. Aim to remove no more than 2 inches of green growth per year.
When To Call A Professional
Some situations are best left to experts. If your arborvitae is very tall or has large dead branches, a professional arborist can do the job safely.
Also call a pro if you suspect disease or pest infestation. They can diagnose the problem and recommend treatment before you trim.
If the shrub is near power lines or buildings, it is safer to hire someone with the right equipment.
Aftercare For Trimmed Arborvitae
Proper care after trimming helps the plant recover and thrive.
- Water deeply once a week if rainfall is low
- Apply a layer of mulch around the base to retain moisture
- Fertilize lightly in spring with a balanced fertilizer
- Watch for browning or wilting in the weeks after trimming
- Do not trim again until the next growing season
Overwatering can be as bad as underwatering. Check the soil moisture before watering. Stick your finger 2 inches into the soil—if it feels dry, water.
Frequently Asked Questions
Can I Trim Arborvitae In The Fall?
It is best to avoid fall trimming. New growth stimulated by cutting may not survive winter cold. Stick to late spring or late summer.
What Happens If I Cut Into The Brown Part Of An Arborvitae?
That part will not regrow. The brown area will remain bare unless surrounding green branches fill in over time. Avoid cutting into brown wood whenever possible.
How Much Can I Trim Off An Arborvitae At Once?
Never remove more than one-third of the green growth in a single season. Removing too much stresses the plant and can lead to dieback.
Do Arborvitae Need To Be Trimmed Every Year?
Not necessarily. If the shrub is healthy and has a good shape, you may only need to trim every 2-3 years. Annual trimming is only needed for formal hedges or fast-growing varieties.
Can I Use Electric Hedge Trimmers On Arborvitae?
Yes, but use them carefully. Electric trimmers can easily cut too deep. Only trim the green tips and avoid the brown interior. Hand pruners are safer for selective cuts.
Final Thoughts On Trimming Arborvitae
Trimming arborvitae is not complicated, but it requires patience and a light touch. The golden rule is to stay in the green zone and never cut into old wood. With the right timing and tools, you can keep your shrubs healthy and attractive for years.
Remember that less is often more when it comes to pruning these plants. A natural, unforced shape looks better and is healthier for the shrub. If you follow the steps in this guide, your arborvitae will reward you with dense, vibrant foliage season after season.
Take your time, make clean cuts, and always step back to check your progress. Your arborvitae will thank you with years of beauty and privacy.