Legal Question in Civil Litigation in California

It depends. Who suppleid the mower, you or the gardener?

Another non legal consideration: If gardener is poor and without much money, it might be the right thing to do to pay for the window replacement yourself.

I don't see why Mr. Kohler thinks who owns the mower matters. What matters from a legal standpoint is whether the gardener failed to exercise ordinary reasonable care under the circumstances and how the rock got there. Fault may be apportioned too. For example, my toddler leaves things in the lawn all the time, including rocks. So if this happened in my yard, and I knew the kid had been throwing rocks and the gardener didn't, it would probably be my fault, and I'd just thank goodness it hit my window and not one of the other gardening crew, because then I'd surely be sued. On the other hand if the rock was obviously in the way of the mower, and the gardener just decided to run over it thinking it wouldn't matter, he is probably liable. If the kid put the rock there and the gardener ignored it, liability would be allocated on some percentage between him and me.

Isn't it your rock?