What Is Arborvitae’s Old Wood? (Growth & Pruning)
Arborvitae’s old wood is the older, often bare stem inside the plant, where green scale-like foliage no longer grows. Arborvitae usually cannot replace enough foliage after a cut into this bare wood, so the spot may stay open. To keep a plant full, prune back to green growth, and trim hedges only within their green outer layer.
A common pruning rule is, “Cut back to a live side branch.” That advice matters with arborvitae because a branch that looks bare may not grow new foliage after you shorten it. When I explain this to a new gardener, I start with a simple check: find the green foliage before choosing where to cut.
Identify Arborvitae Old Wood and Choose Compatible Tools
Old wood is the older interior stem beneath an arborvitae’s green outer growth. It may look brown, gray, or bare, while living foliage appears green and leafy. Knowing the difference helps you avoid cuts that leave permanent gaps and choose a tool suited to the branch, not the whole plant.
Arborvitae are conifers in the genus Thuja. Their foliage is made of small, scale-like leaves arranged along flattened sprays. As a plant grows, newer leafy growth forms toward the outside. Older stems can become shaded and lose foliage, leaving bare wood in the interior.
That bare interior is not the same as a branch that has died. A bare stem may still be part of the plant, but arborvitae generally produce little or no dependable new growth from leafless old wood. The response varies with species, cultivar, plant vigor, and growing conditions. So, do not count on a brown, bare section filling in after a hard cut.
| What you see | What it may mean | Safer next step |
|---|---|---|
| Green foliage at the tip and along the branch | Live leafy growth | Make any reduction cut where a green side branch remains |
| Bare, woody stem with no green foliage | Old wood, or possibly dead material | Avoid cutting it back if that would expose a gap |
| Brown, dry foliage or brittle branch | Possible dieback or damage | Check the branch and plant condition before removing it |
| Green outside, bare inside | Normal dense hedge growth may have shaded the interior | Trim only the green surface; do not cut deeply to “open” the hedge |
Choose tools for the cut
For a selective cut on a small branch, use clean, sharp hand pruners. Loppers provide more leverage for a larger branch that still fits within the tool’s cutting capacity. Follow the tool maker’s limits, and do not force a cut.
A hedge trimmer is for light trimming of green outer foliage, not for cutting deep into the woody interior. Routine arborvitae pruning does not call for a chainsaw. Tool choice depends on branch size and access, not engine displacement. Fuel mix, chain pitch, bar gauge, chain clearance, and engine RPM are not relevant to this job.
Key takeaway: Find the green growth first. If you cannot leave green foliage on the retained branch, the cut may leave a lasting bare spot.
Prune and Shape Without Cutting Into Bare Wood
Pruning means removing selected branches or shoots. Shaping means trimming the outside of a plant to maintain its size or form. For arborvitae, both tasks should preserve green foliage on the parts you keep, because cutting past the green layer can reveal old wood that may not fill back in.
Before cutting, take a moment to inspect the plant. Look for green shoots, dead or damaged branches, signs of stress, and bare areas that could be exposed by trimming. Also check for overhead hazards and nearby utilities. Wear eye protection, gloves, and sturdy footwear. If you use a powered trimmer, add hearing protection and check its guards, handles, and cutting edges before starting.
Make selective cuts
- Remove dead or damaged branches first. Confirm that a branch is dead before removing it. When disease or pests may be involved, avoid spreading affected material to other plants.
- Find a live green lateral. A lateral is a side branch growing from the stem. If a shoot is too long, shorten it back to a suitable green lateral rather than leaving a long bare stub.
- Keep the plant’s natural form. Do not cut flush into the main trunk, and do not make a reduction cut where it leaves only bare wood.
- Work gradually. For routine maintenance, remove no more than about one-third of the foliage in a season. Less is better for a stressed, mature, or heavily shaded plant.
This one-third limit is a ceiling, not a target. A plant that is dry, declining, or already thin may need little or no pruning until its condition is understood. Removing too much foliage at once can leave it with less green growth and make its shape harder to restore.
Trim hedges conservatively
Use a hedge trimmer only on the current green outer growth. Keep green foliage on every retained branch, and stop when another pass would expose brown stems. A hedge can look lush from the outside while its center is bare, so a green surface does not mean it will tolerate a deep cut.
Where the shape allows, keep the top of the hedge slightly narrower than the base. This can help lower foliage receive light. Avoid making the sides so steep or the top so wide that the lower part becomes shaded. The aim is a modest shape, not a drastic haircut.
| Pruning task | Suitable approach | Avoid |
|---|---|---|
| Shortening one overlong shoot | Hand pruners or loppers; cut back to a live green side branch | Cutting the shoot back to a bare stem |
| Removing confirmed dead material | Selective cut with a tool sized for the branch | Assuming all brown interior wood is dead |
| Maintaining a hedge | Light passes over green outer foliage | Repeated deep passes into the brown interior |
| Reducing a large, bare section | Assess options before cutting | Severe “rejuvenation” pruning as a reliable fix |
Key takeaway: Make each cut only when you can retain green foliage on the branch or surface that remains.
Inspect, Clean, and Maintain Pruning Tools
A clean, working tool helps you make controlled cuts and reduces the chance of carrying plant debris between cuts. Before pruning, check that blades are sharp, handles are secure, and guards on powered trimmers are in place. Clean tools after use, and take extra care if you suspect disease or pests.
Dull blades can crush or tear plant material instead of making a neat cut. Do not use a damaged tool or reach into a powered trimmer’s cutting area while it is running. Follow the manufacturer’s instructions for setup, operation, cleaning, and maintenance.
After pruning:
- Remove stuck-on sap and plant debris as the tool maker directs.
- Store tools dry and safely, with cutting edges protected.
- If disease is suspected, clean and disinfect tools between plants using a suitable product according to its label.
- Collect diseased or infested material separately and dispose of it in line with local guidance.
These steps do not make a bad pruning cut harmless, but they support safer, cleaner work. Key takeaway: Check the tool before cutting, and clean it between plants when disease may be present.
Protect Arborvitae Through Seasonal Care
Seasonal care means adjusting pruning to the plant’s condition and the local growing season, rather than cutting on a fixed schedule. Timing can vary by climate, species, and cultivar. Avoid pruning a plant that is under stress until you have considered likely causes, such as poor growing conditions or damage.
Before deciding that a bare section needs trimming, look at the whole plant. Is the soil dry or waterlogged? Is one side shaded? Has the plant been damaged, or is the brown area spreading? These clues do not confirm a cause on their own, but they can show that pruning is not the only issue to consider.
Do not assume that cutting an arborvitae hard will make it bushier. Unlike plants that reliably sprout from older bare stems, arborvitae usually do not replace enough foliage on leafless wood to restore a full surface. A severe cut can therefore turn hidden bare stems into a visible opening.
Practical examples
The following are common pruning situations, not claims about a particular plant:
- One long green shoot sticks out of the hedge. Follow it inward and locate a green side branch. If you can shorten the shoot and leave that green branch, make a selective cut there.
- A hedge is green on the outside but bare inside. Lightly trim the green surface if needed. Cutting back to the bare center is unlikely to fill the gap reliably.
- A large brown opening is already visible. Do not try to erase it with a severe cut. Assess the plant’s health and consider gradual replacement, selective removal, or replacing the plant.
- Several branches look dry or damaged. Confirm what is dead, remove only what is appropriate, and review the plant’s condition before doing more pruning.
If extensive bare wood is exposed, replacement may be more practical than trying to force new growth from old stems. The right choice depends on the size of the gap, the condition of the plant, and whether nearby plants can grow into the space.
Key takeaway: Prune healthy green growth conservatively, and treat widespread bare wood as a planning problem rather than a cue for a hard cut.
Conclusion: Keep the Green Layer
Arborvitae’s old wood is the bare, older stem inside the plant, beneath its leafy exterior. Because dependable regrowth from this wood is limited, protect the green layer: use hand pruners or loppers for selective cuts, and hedge-trim only light outer growth. If a cut would expose bare stems, stop and consider another option.
Frequently Asked Questions
These answers focus on identifying old wood and deciding how to prune without creating avoidable gaps. When a plant is stressed, damaged, or extensively bare, assess its condition before making additional cuts.
What does old wood look like on arborvitae?
It is the older, woody stem inside the plant, often bare of green foliage. It may be brown or gray and can be hidden beneath a green outer layer.
Will arborvitae grow back from old wood?
Usually, not reliably. Arborvitae generally produce little or no dependable new foliage from leafless old wood, though the response can vary by species, cultivar, vigor, and site.
Can I cut an arborvitae back to the trunk?
Avoid it as a routine pruning method. A cut into bare interior wood may leave a permanent gap, and cutting flush into the trunk is not a suitable way to shorten a branch.
Where should I cut an overgrown arborvitae branch?
Shorten it back to a live, green side branch when possible. Do not leave a long bare stub or make a cut that leaves only leafless wood.
Can I use a hedge trimmer on arborvitae?
Yes, for light trimming of green outer foliage. Do not use it to cut deeply into bare stems or to expose the brown interior.
How much arborvitae can I prune in one season?
For routine maintenance, remove no more than about one-third of the foliage in a season. Remove less from stressed, mature, or heavily shaded plants.
Can a bare spot in an arborvitae hedge fill in?
It may not. If the opening exposes leafless old wood, dependable regrowth is unlikely. Avoid severe pruning and consider gradual replacement or replacing the plant.
Should I remove every brown branch?
Not without checking it. Brown foliage may indicate dieback, but bare interior stems are not automatically dead. Inspect the branch and the wider plant before cutting.
Do I need a chainsaw to prune arborvitae?
Routine pruning does not call for a chainsaw. Hand pruners or loppers suit selective cuts; a hedge trimmer is for light trimming of green foliage.
When should I prune arborvitae?
Timing depends on local conditions, species, and cultivar. Avoid pruning a stressed plant without first assessing its condition, and follow local horticultural guidance when timing is uncertain.
(This article was written by one of our staff writers, Evan Bradley. Visit our Meet the Team page.)
