A rotary spreader is a lawn tool designed to quickly distribute granular materials across a wide area. It functions by dropping material onto a spinning disk, which broadcasts the granules in a broad arc, often spanning several feet. This speed and coverage make it the preferred choice over a drop spreader for treating large lawns with materials like fertilizer, seed, or pest control products. Achieving a consistently even application requires careful attention to the setup and technique.
Pre-Application Setup and Rate Setting
Accurate product application begins with careful preparation, as improper setup causes uneven material distribution. The first step involves consulting the product packaging for the recommended flow rate setting, which is typically based on the specific material and spreader model. Since the relationship between the dial setting and the output rate is not linear, simply halving the numerical setting will not necessarily halve the amount of product dispensed.
Once the appropriate setting is determined, the flow gate mechanism should be closed before adding any material to the hopper. The hopper should be filled on a hard surface, such as a driveway or patio, instead of directly on the lawn. This precaution ensures that any accidental spills are contained and can be swept up easily, preventing a concentrated overdose of product that could damage the turf.
Many manufacturers suggest calibrating the spreader to deliver half the desired application rate. This half-rate strategy is utilized in conjunction with a specialized application technique to enhance uniformity across the treated area.
Mastering the Application Technique
Before treating the entire area, establishing a perimeter is necessary to ensure the edges are properly covered and to provide a safe turning area. This is accomplished by making one or two passes around the boundary of the lawn, creating a section often referred to as a header strip. By defining this border, the main body of the lawn can be treated without broadcasting material onto driveways, walkways, or garden beds.
The application across the main area should be performed in parallel lines, moving back and forth across the longest dimension of the space. Maintaining a consistent, steady walking pace is important, as variations in speed can directly affect the spread width and the resulting application rate. A faster pace generally results in a lighter application.
To achieve uniformity and prevent striping, each parallel pass must slightly overlap the previous one. Rotary spreaders naturally distribute material in a bell-shaped curve, with the heaviest concentration near the center and a tapering effect toward the edges. Overlapping the spread pattern by approximately 30 to 50% ensures that the thin outer edges of one pass are reinforced by the heavy center of the next.
The most effective strategy for superior uniformity is the half-rate method, which involves applying half the required amount in one direction, followed by the second half in a perpendicular direction. For example, after applying the first half north-to-south, the user would then apply the second half east-to-west. This cross-hatch pattern minimizes the visual impact of any slight inconsistencies in the spreader’s distribution pattern.
When reaching the header strip or turning at the end of a pass, the flow gate must be shut off while the spreader is still in motion. This action prevents the accumulation of product, which can otherwise result in a localized area of over-application. The flow gate should be re-engaged only after the user has begun moving forward again on the next pass, maintaining the consistent application rate.
Post-Use Care and Storage
Immediately after the application is complete, any remaining granular material must be removed from the hopper. Granular fertilizers often contain salts that are highly corrosive to metal components, and storing product in the hopper can cause serious damage. The remaining material should be poured back into its original bag and tightly sealed for future use.
The spreader should then be thoroughly washed with water to remove all traces of fertilizer dust and residue. Low-pressure water is recommended for cleaning the hopper and agitator mechanism, as high-pressure washing can force corrosive residues into sealed bearings and control linkages. After cleaning, the equipment must be allowed to dry completely before being put away.
To ensure the longevity of the spreader, a light protective lubricant should be applied to all moving components. The axle, gears, and control cables are particularly susceptible to corrosion and benefit from a coating of a rust inhibitor. Proper post-use maintenance ensures the spreader is ready for the next application and maintains its ability to deliver an even pattern.