Snow & Ice Damage to Trees: What to Do (and Not Do)

A wet March snow or a genuine ice storm will do more damage to North Shore trees in six hours than a summer of thunderstorms. The reason is simple weight: a quarter inch of ice accumulation can add a load of several hundred pounds to a single large limb, and half an inch roughly triples the effective weight of the branch structure it coats.

Trees that stood up to every summer storm for forty years come apart under ice, and the species that fail are predictable.

Why ice is worse than wind

Wind loads a tree dynamically. The crown moves, sheds energy, and the whole structure is evolved for it. Ice loads it statically and from every direction at once - every twig, every bud, coated. The crown cannot shed the load, cannot move, and the weight keeps increasing for as long as the freezing rain falls.

Heavy wet snow does the same thing, which is why an early-season or late-season snow is far more destructive than a January snow. In November the leaves are still on, giving the snow enormous surface area to pile on; in late March the sap is moving and the snow is wet and dense. A dry February powder mostly blows through the crown.

The species that fail first here, in rough order:

• Bradford and callery pear - these do not survive ice storms, as a category. The narrow upright branch unions split straight down the trunk.
• Silver maple - fast growth, weak wood, heavy co-dominant stems.
• Siberian elm and box elder - volunteer trees with brittle wood.
• Birch - bends to the ground, often permanently.
• Arborvitae and upright evergreens - splay open and stay splayed.
• Honey locust and ash - better, but a dead ash is in a category of its own. Brittle dead wood plus ice load is why dead ash removals spike every winter.

Oaks and hackberry generally do well. Any tree with co-dominant stems and a tight V-shaped union, regardless of species, is the one at risk - that union is the structural weak point and ice is what finds it.

The one thing never to do

Do not knock the snow or ice off a loaded branch.

This is the most common and most damaging homeowner instinct. A branch bearing an ice load is already at the edge of its strength. Hitting it with a broom adds a shock load in exactly the wrong direction and is a reliable way to snap a limb that would otherwise have survived the thaw. Frozen wood is also substantially more brittle than the same wood in July - the fibers do not flex, they break.

The same goes for pulling, shaking, or trying to straighten anything while it is frozen.

Light, dry snow on a small ornamental can be gently brushed upward and outward with a soft broom, if you must. Ice: never. Ice does not come off without taking bark and buds with it. Let it melt.

What to do instead

Stay out from under loaded trees. Branches let go without warning, and they let go during the thaw as often as during the storm. Keep cars out from under the crown and take the long way around to the garage.

Look for wires. Ice storms bring down conductors along with limbs. A downed wire is 911 and ComEd, immediately, and nobody goes near the tree. See trees near power lines and tree on your house or a power line.

Identify the hangers. The real post-storm hazard is the widow-maker - a broken limb that did not fall, now hanging in the crown or caught on another branch. These come down later, on their own schedule, and they are the reason someone gets hurt a week after the storm. Over a driveway, walk, or play area, a hanger is a prompt call.

Photograph the damage before any cleanup, for insurance. Does homeowners insurance cover tree removal covers what the policy actually pays for, and the short version is that damage to a structure is usually covered while cleanup of a tree that fell in the yard often is not.

Do not get on a ladder in winter to cut anything. Frozen ground, ice underfoot, overhead load. This is the single worst DIY setup in tree work.

What can be saved

Once things have thawed and the hazards are off, the assessment is reasonably straightforward.

Usually saveable:

• Clean breaks on small to medium branches. Prune back to the branch collar at the nearest lateral or the trunk, and the tree handles it.
• Damage to under about a quarter of the crown on an otherwise healthy tree.
• A bent but unbroken young tree. Many straighten themselves over the next season once the load is off. Give it a full growing season before intervening. Staking a young tree back upright can work if the bend is recent and the root plate did not lift, but it is a one-season fix, not a permanent cable.

Usually not:

• A split at a co-dominant union running down into the trunk. This is the classic ice failure and it is a structural defect now, not a wound. Sometimes cabling and bracing can hold a valuable tree together - that is a real option worth asking about on a specimen tree - but on a Bradford pear it is money after bad.
• More than about half the crown gone. The tree cannot feed itself back into shape.
• A lifted or heaved root plate. Soil cracking or a mound on the opposite side of the lean means the root system moved. That tree is unstable regardless of how the crown looks. See 7 signs a tree is dangerous.
• Splayed-open arborvitae. They rarely resume their original form, and tying them back is a long-term disappointment.

Resist the urge to have everything "cleaned up" aggressively. Topping or heavily cutting back a storm-damaged tree produces weak regrowth and sets up the next failure. The right post-storm pruning is restorative and conservative: remove the broken, leave the sound, and let the tree re-establish. When to remove a tree vs save it covers how that call gets made.

Preventing it before next winter

Ice damage is one of the more preventable tree failures, and all of the prevention happens in the dormant season.

Structural pruning is the whole game. Reducing the end weight on long overextended limbs, removing deadwood that will break under any load, and addressing co-dominant stems while the tree is young is what separates the trees that come through an ice storm from the ones that come apart. This is ordinary tree trimming and pruning work, done in winter, and it is the best value in tree care.

Deadwood is the first thing to break. A crown full of dead limbs is a yard full of debris waiting for the first wet snow.

Dead ash cannot wait. A standing dead ash is the highest-risk tree in any North Shore yard going into winter. See why dead ash cannot wait.

Cable the trees worth cabling and plan to replace the ones that are not. A Bradford pear with a splitting union is a decision you can make in October or have made for you in February.

Winter is also the cheapest time to do the work. Frozen ground, easier access, clearer scheduling - why the dormant season wins and the best time of year to remove a tree both cover why.

One more, unrelated to ice but entirely a winter issue: the salt your street and driveway get all season does real damage to the trees along them. See road salt and tree damage.

The short version

1. Never knock ice off a branch. Let it melt.
2. Stay out from under loaded trees, including during the thaw.
3. Hangers are the real hazard after the storm clears. Get them down.
4. A split co-dominant union is structural. A clean branch break is a wound. Different decisions.
5. Prune for structure in the dormant season. That is what prevents next year's damage.

Lake-effect snow and freezing rain off the lake hit Evanston, Wilmette, Winnetka, Highland Park, and Lake Forest hardest, and the ice line often sits right across the North Shore. If a storm left you with broken limbs or hangers, request a free on-site estimate, or use the online estimate tool for a range.