A method of installing a roof planter assembly includes providing first and second planter modules each including a bottom wall and a plurality of sidewalls that cooperate with the bottom wall to form an interior space adapted to receive plant matter therein, wherein at least a pair of the plurality of sidewalls cooperate to form a corner therebetween, the corner including first and second portions along a length of the corner and having bottom and top edges, respectively, that are entirely horizontally offset and spaced from one another.