Broadcast Spreader Technique
Broadcast spreaders do a great job of spreading grass seed, fertilizer and weed killer on larger lawns because they throw the material out more consistently over a wide area. However, unless you know how much area they cover for each type of product, you can end up spreading too much or too little and get bad results.
The best way to find out the actual dispersal pattern for your broadcast spreader is to do a test run on your driveway and then measure the results. Clean off a 12 x 20-ft. section of the driveway. Close the flow lever on your spreader and set the controls for the product you're using. Fill the spreader—do this on the driveway or sidewalk to avoid spills on the grass—then open the flow lever and push the spreader several feet down the center of the driveway at your normal pace, continuing for a few steps after you close the hopper.
Measure the average dispersal pattern to the sides and front. (Note: The right side of the dispersal pattern for spreaders is wider than the left side.)
Sweep up the test material and dump it back into the spreader, then apply the material to your lawn, walking back and forth in the long direction on your lawn (Figure A). Overlap each course 6 to 12 in., but close off the flow when you make tight turns.
Walk the spreader up the center of the driveway, then measure the total width and the width on each side.
Apply a "header strip" around the perimeter of the yard, then fill in the middle. Shut off the spreader when you turn.