Load the lawn spreader with castor oil pellets. Generally, 3.75 lbs. of product is enough for up to 2,500 square feet, but check the packaging to determine the proper amount for the particular brand you use.
Run the spreader along the edges of the lawn, then push it back and forth in the area bounded by the treated edges. This method helps you apply the castor oil pellets evenly.
Reapply the castor oil pellets every two months or more frequently in rainy seasons.