Calgary sits in one of the most hail-prone regions in North America. Every summer, powerful thunderstorms roll off the Rockies and dump everything from pea-sized pellets to golf-ball hailstones on our neighbourhoods. While the damage to roofs, cars, and siding gets most of the insurance attention, your trees take a beating too. Understanding how to assess and respond to hail damage can mean the difference between a tree that recovers fully and one that declines over the following years.
Immediate Safety First
After a severe hailstorm, your first priority is safety. Do not go near trees until the storm has fully passed. Look for hanging branches, split limbs, and leaning trunks from a safe distance. If a tree has fallen on power lines or a structure, stay well clear and call 911 or ENMAX. Do not attempt to clear debris that involves downed electrical lines under any circumstances.
Once it is safe to approach, walk your property and identify any immediate hazards: branches that are broken but still hanging in the canopy, limbs that are cracked and could fall, and trees that are leaning at a new angle. These are priority items that need professional attention before anyone spends time under or near those trees.
Understanding Hail Damage to Trees
Hail damages trees in several ways, and not all of them are immediately obvious. The most visible damage is broken branches and stripped foliage. Large hailstones can snap branches outright, while even moderate hail strips leaves and shreds remaining foliage. A tree that was fully leafed out before a storm can look almost bare afterward.
Less visible but often more consequential is bark damage. Hailstones striking the trunk and major branches create wounds by bruising and breaking the bark. On young trees with thin bark, these wounds can be severe enough to girdle branches or create entry points for disease. On mature trees with thick bark, the impact damage is usually superficial but can still create openings for fungal infection.
The third type of damage is the most insidious: physiological stress. A tree that loses 50 to 80 percent of its foliage in a hailstorm has lost most of its ability to photosynthesize for the remainder of the season. It must draw on stored energy reserves to push new leaves, which depletes resources it would normally use for root growth, winter preparation, and disease resistance.
Assessing the Severity
Not all hail damage warrants the same response. Here is how to categorize what you are seeing:
- Minor damage: Some leaf stripping and small twig breakage, but the canopy structure is intact and the majority of foliage remains. Most trees recover from this level of damage without intervention.
- Moderate damage: Significant leaf loss, some branch breakage, visible bark wounds on the trunk or main limbs. The tree will likely recover but may benefit from supportive care.
- Severe damage: Major branch loss, extensive bark damage, most foliage stripped. The tree's survival depends on its species, age, health before the storm, and the care it receives afterward.
- Catastrophic damage: Split trunk, uprooting, loss of the main leader, or destruction of more than half the major scaffold branches. Removal may be the most practical option.
What to Do in the First Week
Resist the urge to do everything at once. In the days following a major hailstorm, tree service companies in Calgary are overwhelmed with calls. Use the first week to assess and prioritize rather than rushing into work.
Remove any branches that are hanging dangerously or blocking access. If you can safely reach them from the ground with a hand saw, go ahead. Anything that requires a ladder or climbing should wait for a professional. Clean up fallen debris from the lawn and garden beds so you can assess the overall situation clearly.
Water your damaged trees deeply. A stressed tree needs adequate moisture to fuel its recovery response. Give each affected tree a slow, thorough soaking, especially if the post-storm weather is hot and dry.
The Recovery Period
Most healthy trees that sustain minor to moderate hail damage will push a second flush of leaves within two to four weeks if the damage occurs early enough in the growing season. Storms in June or early July leave enough growing season for trees to partially rebuild their canopy. Storms in August or September leave less time, and the tree may not fully re-leaf before fall.
During recovery, avoid fertilizing damaged trees. Fertilizer stimulates growth, which is counterproductive when a tree is trying to stabilize and heal. The tree needs its energy reserves for wound closure and defensive chemistry, not for pushing new growth. Wait until the following spring to consider fertilization, and only if the tree shows signs of nutrient deficiency.
Do not prune more than necessary in the weeks following the storm. Over-pruning a stressed tree removes energy-producing foliage and stored carbohydrates that the tree needs for recovery. Limit initial pruning to hazard reduction — removing broken, hanging, and structurally compromised branches. Detailed corrective pruning can wait until the following dormant season when you can better assess what the tree needs.
Insurance and Documentation
If you have homeowner's insurance, tree damage from hailstorms may be covered, particularly if a tree fell on your house, garage, fence, or other insured structure. Most policies cover the cost of removing a fallen tree that has damaged a structure, but they typically do not cover the removal of a standing damaged tree unless it poses an immediate hazard.
Document the damage thoroughly with photographs before any cleanup begins. Take wide shots showing the overall scene and close-ups of specific damage to each tree. This documentation is valuable for insurance claims and for tracking recovery progress over the following months.
Long-Term Monitoring
Hail damage effects can take one to three years to fully manifest. A tree that appears to recover well in the first season may show delayed decline in subsequent years as the cumulative stress catches up. Watch for increasing dead wood in the canopy, smaller than normal leaf size, reduced growth, and bark cankers developing at hail impact sites.
Annual monitoring by a certified arborist for the first two or three years after significant hail damage is a worthwhile investment. Early detection of secondary problems like disease entry through hail wounds allows for timely treatment that can prevent further decline.