Property Line Rights
For those who are trying to find the answer to the question "can you plant trees on a property line", the answer may not be as simple as you think. There are various rules and regulations that are defined by towns and cities all over the United States about the legal rights of property owners when it comes to property lines. While the property line is theoretically considered the line that borders two parcels of land, there may be other circumstances where towns or cities have rights to this land as well.
Chances are that when you purchased your home, a land survey was done. This survey clearly delineated the lines between your property and the abutting properties. In addition, the property may have also shown things like sewer lines, utility poles and perhaps even wetlands that are near the property.
In the event that there is a sewer line (whether private sewer or city/town sewer) on or near the property line, the owner (private or muncipality) has the right to access that line. In addition, properties that abut wetlands mean the municipality has control over what goes on on the line. These events create what is called a property easement, allowing the owner the right to access your property.
Easements versus Encroachment
Easements and encroachments are not the same thing. Easements are created when another property owner (or interested party) requires access to property that may only be accessed from the primary owner's property. In some cases, this could be sewer lines laid by the town or wetlands that are beyond the property line but have no access from the road. In some instances, homes were built behind other homes, resulting in a right of access easement where the homeowner of the back lot could only access it via the driveway from the front lot.
Encroachments on the other hand are controllable intrusions. Fences, shrubs and trees are common encroachments. In some cases, if a homeowner does not fight an encroachment through the legal system, the property line may eventually be changed.