Will putting a nail in a tree harm the tree?
Certified GKH Gardening Expert
Driving a nail into solid wood of a healthy, vigorous tree is not likely to cause immediate harm. But it's certainly not a good thing to do and it should be avoided if possible; there may be longer term negative consequences. There is potential for introducing pathogens. The degree of harm depends on the several factors, including the tree species and its ability to resist infection and decay.