If you live in Los Gatos, or anywhere along the Santa Cruz Mountains like Almaden, Saratoga or Los Altos, you probably live with trees very near your home, as the San Jose area values its "urban forest". And often enough, those trees arch over fences and property lines.

Ever wonder how tree ownership works in regard to property lines? Well, last week I found out. I had a tree and property line question here in Silicon Valley so called the California Association of Realtors legal hotline and spoke to an attorney about it. (The lawyer referenced case law and sent me info on it: Miller and Starr §§ 14:15, 14:16.)

If the tree trunk is located wholly on one property, the tree is "owned" by that property owner. Even if the branches go over the property line. If the trunk straddles the property line, you have a shared tree.

What about trimming those branches that go over a neighbor's yard?

First of all, this is the wrong time of year for trimming trees. It is best to do it in spring. But if tree branches are an issue for someone now, the neighbor with the branches reaching onto his or her yard has the right to trim those branches back to the property line (and pay for it himself or herself). The neighbor cannot demand that the tree owner pay to trim the branches. And the neighbor cannot harm the tree or kill it (or chop it down). If the neighbor harms the tree, he or she could be liable for damages.

This is also true of the roots. The neighbor can trim the roots if they are really causing a problem, but cannot harm the tree. Cutting back roots can cause trees to die or become so unstable as to fall down, so trimming roots should be the last resort.

The tree owner's responsibility regarding the tree and the property adjacent to it is simple: if the tree harms the neighbor's property, the tree owner could be liable for damages. So enormous oak trees with limbs hanging over a neighbor's roof could spell disaster (oak trees are known for simply dropping big branches on hot summer days). Tree branches interwoven with phone lines could be a problem in a winter storm too.

It's always best to talk with the neighbor before doing anything, of course, and to give them a little notice. If you're the neighbor, ask when the tree owner wants to trim the tree.(It will probably be in spring.) If you're the tree owner, ask your neighbors when you plan to trim your tree if they'd like you to trim the part hanging into their yard too. Some will say yes, and some no!