By June the old trees around Marquand Park throw a shade so deep that the lawns beneath them learn a different kind of growing — slower, cooler, asking for a lighter hand. The Persian Rose Garden tends Princeton lawns in that spirit, cutting at a height the grass can live with and trimming close around trunk flare and bed edge without wounding what is already there. Shaded patches get overseeded, the sunny stretches get fed, and leaves are lifted before they mat down and smother the turf beneath. What a household notices is not the machinery but the walking: the give underfoot, the even green seen from a porch step. Week to week, that is what the work is aiming at.