Crown cleaning is the removal of dead, dying, diseased, broken and weakly attached branches from a tree's crown, without cutting off healthy living growth. Deadwood does not recover, and in Ottawa it tends to come down in wind, ice or heavy wet snow, so it is best taken out before winter weather tests it. It is one of the simplest ways to make a mature tree safer, and the City of Ottawa does not require a permit for pruning that maintains a tree's health and follows good arboricultural practice.
What crown cleaning actually removes
"Crown" is the part of the tree made up of its branches and leaves. Crown cleaning (some people search for it as crown clearing) is a specific, limited kind of pruning. In arboricultural standards it covers the selective removal of:
- Dead branches, from small twigs to limbs as thick as your leg.
- Dying and diseased branches, such as limbs with cankers, fungus or sparse, stunted leaves.
- Broken and hanging branches, including ones snagged in the crown after a storm.
- Weakly attached branches, for example limbs growing from a tight V-shaped fork with bark squeezed between them.
- Crossing and rubbing branches that wear wounds into each other.
- Water sprouts and suckers growing straight up from branches or the base.
What it does not do is shrink the tree. Crown cleaning is not thinning the crown for light, raising it for clearance or reducing its height. Those are different jobs with different goals, and a tree can need one without the other.
Why deadwood matters more in Ottawa
A dead branch has no flexibility left. A living limb bends in a gust and springs back, but dead wood is brittle and snaps. It also gets heavier when it holds snow or freezing rain, and our freeze and thaw cycles gradually weaken the attachment point.
That is why deadwood tends to fall at the worst times: on a windy afternoon, after an ice storm, or in the first heavy snowfall. A branch that has been hanging in a crown for weeks can drop without warning on a driveway, a car, a deck or a person.
Dead wood also invites decay. Fungi that feed on dead branches can work their way back toward the trunk, and open wounds give insects a way in. Removing a dead limb properly, back to the right point, lets the tree seal the wound.
How to spot deadwood
The easiest time to see deadwood is in summer, when living branches are in leaf and dead ones are bare or hold brown, shriveled leaves. If you notice a bare limb in July, note which one it is. In winter, with no leaves, a dead branch and a dormant one look much alike.
If you are checking now, these signs help:
- Bark that is loose, peeling or missing, with bare wood showing underneath.
- No buds at the tips. Living twigs carry small, firm buds. Dead twigs have none or have shriveled ones.
- A snap test. A living twig bends before it breaks. A dead one snaps cleanly and looks dry and tan inside, not green or moist.
- Fungus growing on a limb, such as shelf-shaped brackets, which often signal decay.
- A limb that holds old brown leaves well after the others have dropped.
- A branch lying in the crown at an unnatural angle, or one resting against another.
One caution: a few dead twigs in a large tree are normal. Large dead limbs, or a lot of deadwood across the whole crown, are a different matter. That can point to a stressed or declining tree and is worth having an arborist look at, because pruning the symptom does not fix the cause.
Dead branches versus a dead tree
Removing deadwood is for a tree that is mostly alive. If most of the crown is dead, the question changes from pruning to whether the tree should come down. Under Ottawa's Tree Protection By-law, the exemption for a dead tree only applies when an arborist confirms it is dead, and ash trees killed by emerald ash borer are exempt from the permit requirement. Our guide to Ottawa tree removal permits lays out the rules, and our post on when you need an arborist report explains what a City application involves.
When to do it
Deadwood can be removed at any time of year, because season does not matter once a branch is a hazard. For routine crown cleaning there are good reasons to schedule it for the fall or winter:
- Pruning cuts made in the dormant season stay clean, and insects and fungi are less active.
- With the leaves down, an arborist can see the branch structure and any cracks, cavities or poor forks.
- It clears the weak wood out before the heaviest snow and ice loads.
- Frozen ground means less disturbance to the lawn and beds below the tree.
Dead and hanging branches that are an immediate danger should not wait for the right season. If a limb is hanging over a driveway or a roof, it is worth dealing with right away.
Why this is a job for a trained crew
Dead wood is unpredictable. It can fail under the weight of the person climbing it, and a branch under tension can swing or kick when cut. The risk goes up with height, with any limb close to a power line, and with any tree you cannot safely reach from the ground. If a branch is near a utility line, stay away and call the utility.
A professional crew also knows where to cut. A good pruning cut is made just outside the branch collar, the slightly swollen ring where a branch meets the trunk or a larger limb. Cutting flush with the trunk, or leaving a long stub, slows healing and invites decay. Wound paint and sealants are not needed.
Frequently asked questions
Is crown cleaning the same as tree trimming?
Crown cleaning is one type of trimming. It removes dead, diseased, broken and weak branches only. Trimming can also mean thinning, shaping or raising the crown, which remove living branches for other reasons.
Do I need a permit in Ottawa to remove dead branches?
No. The City does not require a permit for pruning that maintains a tree's health and follows good arboricultural practice. Heavy cuts, topping or root damage can still count as injuring a protected tree, so keep the work limited to what the tree needs.
Can I cut dead branches myself?
Small, low branches that you can reach from the ground with hand tools are manageable. Anything that needs a ladder, a chainsaw above shoulder height, or is near a power line or over a building is a job for a trained crew.
Will removing deadwood save a declining tree?
Not by itself. It removes a hazard and gives the tree less to carry, but it does not fix the underlying cause of the decline. If a lot of the crown is dying, an arborist should find out why.
When is the best time to remove deadwood?
Any time. If you are choosing a time for routine work, fall and winter are good, but dead limbs over a driveway, roof or play area should not wait.
Get your trees checked
Tree King does tree pruning in Ottawa, including deadwood and storm-damaged limb removal, and can advise on whether a tree needs an arborist or removal. Call 613-627-2017 or book a free quote.
Sources
- Tree Protection By-law No. 2020-340 (City of Ottawa)
- ANSI A300 (Part 1) Pruning standard, definition of crown cleaning (Tree Care Industry Association)