A fertilizer spreader may be used to dispense fertilizer, grass seed and granular weedkillers evenly and accurately. The spreader is made up of a hopper set on wheels, which may be manoeuvred using a long handle. The hopper should have a switch that adjusts (or stops) the rate of flow of material. The flow rate may be calculated as follows:

Calibrating a Spreader

To calculate the distribution rate for any machine, you must first calibrate the spreader. Chalk out an area of approximately 4 sq m (4 sq yards) on a flat, dry area of asphalt or concrete. Quarter fill the machine, and then set it to "Medium". Spread the fertilizer (or grass seed or weedkiller) over the marked area as evenly as possible at the same speed you would use on the area you are going to work on, then brush up all the material and weigh it. Divide this weight by the area (in this case, 4 sq m or 4 sq yards) to calculate the application rate in grams per square metre or ounces per square yard. Adjust the machine and re-test until the application rate is at the desired level.

Using the Spreader

Once the machine is calibrated, weigh out the right amount of material for the entire area and divide it in half. Put the first half in the spreader, making sure that the spreading holes are closed. Apply the first half in one direction, working up and down the area in the same way as mowing a lawn; however, remember that each strip should join but not overlap the last. You may want to set out garden line or canes on the ground as a guide; both can be moved as you proceed. Close off the supply hole as you turn at the end of each row. Apply the second half at right angles to the first application strips and continue until you have finished the area.

After applying fertilizer, ensure that you wash the machine out thoroughly; fertilizers are corrosive and can damage any metal parts.