Spring is the best time to catch winter damage on your Toronto trees before small problems become expensive ones. The six things worth inspecting closely are dead and hanging branches, frost cracks, co-dominant stems, root heave, Emerald Ash Borer signs, and fungal cankers at branch collars. Most trees come through winter without issue. The ones that do not can pose real hazards if the damage goes unnoticed until a branch comes down in a summer storm.
Toronto winters are hard on trees. Freeze-thaw cycles split bark, ice weight snaps structurally weak branches, and salt spray from roads can burn foliage buds and stress roots along boulevards and driveways. Spring is the window when damage becomes visible as the tree either leafs out or reveals what did not survive.
The stakes are not just cosmetic. A dead branch 30 feet up weighs more than most people expect, and once the bark dries out and the wood becomes brittle, it can fail with no warning. Catching it in April is far safer and less expensive than dealing with it after it lands on a fence, a car, or someone.
A dead branch in the canopy is called a widow maker for a reason. Look for branches with no leaf buds where the surrounding canopy has started to green up. Hanging branches that are caught in the crown without touching the ground are especially hazardous because they can fall at any angle. If you see one, do not walk under the tree until it is removed.
Frost cracks are vertical splits in the bark caused by the rapid temperature changes of Toronto winters. Cold nights followed by warm sunny days cause the bark to contract and then expand faster than the wood inside. You will often see a long vertical crack on the south or southwest side of the trunk. Most frost cracks do not kill a tree on their own, but they create entry points for decay and insects. An arborist can assess whether intervention is needed.
Ice load over the winter is the most common trigger for co-dominant stem failures. A co-dominant stem is where two equally sized leaders grow upward from the same point, often with bark pinched between them. That included bark weakens the attachment over time. Spring is when to look for any new cracking or shifting at that union point. If one stem is leaning slightly more than it was last fall, that is worth an arborist assessment before summer.
Ground freeze and thaw can lift the soil around a tree's base and shift surface roots. If you notice the ground has heaved noticeably around the tree base over winter, check whether the tree itself has shifted. A small tilt that was not there before, especially in a larger tree, is worth having looked at. Root heave on its own is usually not serious, but if it is accompanied by visible root damage or soil cracking, an arborist should assess stability.
If you have ash trees, spring is when EAB damage becomes hardest to miss. Look for D-shaped exit holes in the bark (about 3-4mm wide), S-shaped feeding galleries visible under peeling bark sections, crown dieback starting at the top and working down, and epicormic shoots sprouting from the trunk or major branches. EAB has spread through most of the GTA and an ash showing any of these signs should be assessed immediately. In many cases, treatment is still an option if caught early enough.
Cankers are sunken, discoloured areas in the bark where fungal or bacterial infections have killed a section of tissue. They often appear on branches that were wounded by winter damage. Similarly, look for mushrooms or conks growing at the base of a tree or from the trunk. These are the fruiting bodies of fungi that decompose wood from the inside out. A tree showing significant fungal growth at the base warrants an urgent structural assessment.
When to call now vs when to wait:
Spring is an excellent time to have structural pruning done on most deciduous trees. Crown cleaning (removing dead, crossing, and rubbing branches), crown raising (removing lower branches for clearance), and structural subordination (reducing the size of competing leaders) are all best done before the full leaf-out. Pruning wounds callus over faster in spring and the tree's energy is directed toward new growth that closes wounds quickly.
Species timing matters. Oaks and elms should be pruned in late fall through early spring only, before April, to reduce exposure to oak wilt and Dutch elm disease spores. Maples bleed sap heavily in early spring but this does not harm the tree. Fruit trees are best pruned just before bud break for the best disease control.
Our ISA certified arborists conduct full spring assessments covering structural integrity, winter damage, pest and disease signs, and pruning recommendations. We serve Toronto, North York, Etobicoke, Scarborough, East York and surrounding areas.
If a tree has no leaf buds anywhere on its canopy by late May and the scratch test confirms dead wood throughout, the tree is gone. A full failure to leaf out can result from severe root damage, drought stress from the previous summer, construction impact, or disease that was not visible externally. At this point the tree should come down before the wood dries out and becomes unpredictable.
Under Toronto's Chapter 813, even a dead tree requires a permit for removal if it measures 30cm DBH or more on private property. Our arborist handles the permit application as part of the removal process. See our guide to removing a dead tree in Toronto for the full process.
After a thorough spring inspection, you will often end up with a category of trees that do not look great but are not obviously dead. A maple that leafed out sparsely. An oak with a large dead section on one side but healthy foliage elsewhere. A spruce with browning at the tips. These trees warrant a professional assessment rather than either immediate removal or indefinite waiting.
An ISA certified arborist can assess tree health more thoroughly than a visual inspection allows. Mallet testing for hollow wood, resistance drilling in suspected decay zones, and crown density assessment are all part of a proper structural evaluation. For trees showing signs of disease, an arborist can identify the pathogen and advise on whether treatment is viable or whether decline is inevitable.
The goal of a spring assessment is not to remove trees. It is to triage what you have. Most trees get a clean bill of health. A few need pruning. Occasionally one needs to come down. Getting that picture in May means you can schedule the work at your pace rather than reacting to an emergency in July.
A formal arborist consultation for a residential property in Toronto typically costs $150 to $350 and provides a written report with findings and recommendations for each tree assessed. For properties with a significant number of mature trees or specific concerns, we can build a multi-year care plan as part of the assessment. If you proceed with pruning or removal work following the assessment, the consultation fee is often applied toward the work quote.
For a quick visual assessment with verbal recommendations rather than a written report, many arborists including the professionals we work with will visit a property at lower or no cost when combined with a quote for identified work. Call us and describe what you are seeing and we will advise on the right type of visit for your situation.
When is the best time to prune trees in Toronto?
Late winter to early spring is the best window for most deciduous trees in Toronto. Trees are still dormant or just breaking dormancy, pruning wounds seal quickly, and fungal spores from diseases like oak wilt have not yet peaked. Oaks and elms should not be pruned in summer at all.
How do I know if a branch is dead or just slow to leaf out?
Scratch a small section of bark with your fingernail. If the layer underneath is green, the branch is alive. If it is brown and dry all the way through, the branch is dead. Dead branches in the canopy should come down promptly. They become brittle and can fall without warning.
Does a spring pruning job need a permit in Toronto?
Pruning does not require a permit in Toronto. Only the removal of a tree meeting the Chapter 813 diameter threshold (30cm DBH on private property) requires a permit. If extensive pruning is needed on a tree that has not leafed out at all, an ISA certified arborist should assess whether removal may be the appropriate outcome.
How do I check my ash tree for Emerald Ash Borer?
Look for D-shaped exit holes in the bark about the size of a small fingernail, S-shaped galleries visible under peeling bark, crown dieback starting at the top, and epicormic shoots sprouting from the trunk. A certified arborist can confirm EAB and advise on treatment vs removal.
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