Q&A: Do Nails Hurt Trees?
Q: Does nailing something to a tree hurt the tree?
A. Good question. Generally, no, something the size of a nail hammered into a tree won't hurt it. The nail would most likely be inserted about an inch to an inch and a half into the bark. "The tree should compartmentalize and heal the wound around it," says Grant Jones, technical advisor with Davey Tree Company in Kent, Ohio.
Where there might be cause for concern, Jones says, is with trees that are young and small or have signs of existing decay or pest problems. With such trees the nail could damage the tissues responsible for moving water and nutrients throughout the tree's system. The tree could take longer to heal and therefore be under more stress. Stressed-out, unhealthy plants are more vulnerable to pest or disease problems than healthy plants.
Keep in mind that something heavy — a piece of garden art or someone lying on a hammock — hanging from the nail on a young or diseased tree, this added weight could put additional stress on the tree, ultimately leading to tearing of the bark or opening wounds to pests.
But generally speaking, it would take a lot more than that to harm the tree. Other sources of damage include lawn mower or string trimmer damage to tree bark, weather-related injuries, diseases or insects, construction damage, soil compaction, too much or too little water, the presence of too much pavement and poor cultural practices such as tree topping and improper pruning.