Lightning damage to trees: what the sources describe
Lightning can strip a band of bark, split a trunk or leave no mark at all on the outside. The Maryland and South Dakota extension services and the Missouri Botanical Garden describe what happens inside the tree and why the full damage can take time to show.
Checked against the sources at the bottom of this page on October 8, 2026. Rules, fees and pay change: the source has the last word.
This page describes what the named extension services and the Missouri Botanical Garden say. It does not diagnose a tree, say whether any struck tree is safe or unsafe, or tell anyone whether to keep, treat or remove one. Lightning is a one-off event, unlike the seasonal stresses in the rest of this group, and the sources agree that assessing the result is hard.
What the sources say happens in the tree
University of Maryland Extension (Home and Garden Information Center, updated March 1, 2023) says that when lightning hits a tree, water in the cells under the bark is heated past boiling, and the steam causes an explosion that removes strips of bark. The Missouri Botanical Garden gives the same mechanism: the electricity vaporizes water in the trunk, which expands and can split the tree open. South Dakota State University Extension (Tree Pest Alert, August 5, 2026, John Ball) describes a linden struck during storms that left half the tree as large splinters, and offers two common explanations for shattered trees: the discharge turns water in the sapwood to steam, and the pressure wave of superheated air can compress the bark and wood.
The range of damage the sources describe
Maryland describes a continuous groove of bark stripped along the whole length of the trunk or main branch, and says a crack that does not run the full length may point to a side flash, where electricity travels down the trunk and then jumps to an object with less electrical resistance. It says a deeper strike may blow the whole tree apart, that the trunk may or may not show blackened or charred areas, and that in some cases the internal wood or roots may burn with no obvious outside symptoms. Maryland ties the wide range of damage to the intensity of the strike, the moisture on and in the tree, and the tree's type and structure. Missouri says that, of the trees that are struck, twenty percent may show no visible injury and have minor damage, while in other cases only a strip of bark is blown off one side, usually from top to bottom. South Dakota adds that the discharge can leave injured roots, which it says may result in slow decline.
Why the full result takes time
Missouri says assessing overall damage and a tree's chances of recovery can be difficult, and that the full extent may not be clear for weeks, months or even years. Maryland says, if possible, to wait a full growing season to determine the extent of the damage. Missouri describes cases where only a narrow strip of bark is lost and says healing can still occur, and adds that damage which looks slight at first can become extensive over time. South Dakota describes a split open to the interior that it says exposes the wood to decay fungi, and notes the explosive force may have caused hidden defects. These are the named sources' views of one case each; this page does not say what any particular tree's outcome will be.
What the sources list for management
Maryland lists pruning damaged branches soon after a strike, having an arborist prune if the tree is large, hazardous or near power lines, and, where the cambium under loose bark is still moist, tacking bark back in place and covering it temporarily, or otherwise removing loose bark. It advises consulting an arborist for a valuable specimen or a tree that has become a hazard to people or property. Missouri lists dealing with dangerous branches, waiting to see how the tree responds, and cleanly removing loose bark so the wound can heal. For the decay and defect side, see the guide on cracks in trees and the page on human-caused damage.
The other pages in this group are listed on the weather, soil and chemical damage page.