The title is usually placed in the center, either above or below the graph. The proper form for a graph title is "y-axis variable vs. x-axis variable." For example, if you were comparing the the amount of fertilizer to how much a plant grew, the amount of fertilizer would be the independent, or x-axis variable and the growth would be the dependent, or y-axis variable. Therefore, your title would be "Amount of Fertilizer vs. Plant Growth.
