Granular fertilizer consists of dry pellets designed to provide a steady supply of nutrients to a lawn or garden over time. These small, solid particles are popular because many formulations offer slow-release properties, feeding the turf for weeks after application. The correct methodology for spreading this material is paramount to achieving a uniform result and preventing chemical burns on the grass. A precise application process ensures the entire area receives the intended dose, activating the nutrients for healthy, consistent growth. Following this process prevents a lawn marked by green stripes or scorched patches.
Essential Preparation and Equipment Selection
Before application, mow the lawn to the regular height, allowing the granules to fall closer to the soil surface where they can be absorbed. The first step involves selecting the appropriate spreading tool, usually either a drop spreader or a broadcast spreader. A drop spreader releases granules straight down in a precise band, making it ideal for smaller lawns or areas near flower beds.
A broadcast or rotary spreader uses a spinning disc to scatter the granules in a wide arc, covering a much larger area more quickly. This type is better suited for large, open lawns because its wider coverage minimizes the number of passes required. Wear gloves and eye protection, as the chemical nature of the granules can irritate skin and eyes. Fill the spreader on a hard surface, such as a driveway, to contain any spills, which should then be swept up and returned to the hopper.
Calculating Application Rate and Calibrating the Spreader
The most technical aspect of the process is determining the exact amount of product needed and translating that to a spreader setting. This calculation starts by measuring the square footage of the area to be treated, excluding non-lawn areas like patios or walkways. The fertilizer bag provides the manufacturer’s recommended application rate, typically expressed in pounds of product per 1,000 square feet.
The next step is to match this rate to the spreader’s mechanical dial setting, which controls the size of the opening at the bottom of the hopper. Most fertilizer bags include a chart listing suggested settings for various common spreader models. Because settings can vary significantly, it is prudent to perform a small calibration test before treating the entire lawn.
A simple calibration involves measuring a known amount of fertilizer and spreading it over a measured test area to confirm the coverage matches the recommended rate. If the fertilizer runs out too quickly, the setting is too high; if there is too much left, the setting is too low. Adjusting the flow rate based on this test prevents both ineffective under-application and over-application, which can cause severe turf damage.
The Physical Application Technique
With the correct rate established, the physical application begins by creating a perimeter strip around the entire area. This border pass provides a buffer for turning and ensures the edges of the lawn receive a full application. The remainder of the area is then treated by walking in parallel, back-and-forth lines.
Maintaining a consistent, steady walking speed is necessary because the application rate of most spreaders is directly affected by the speed of the operator. When using a drop spreader, the wheel tracks from the previous pass should slightly overlap the new path to avoid leaving untreated gaps, which can result in visible stripes. Conversely, with a broadcast spreader, the overlap must be precisely judged to ensure the edge of the broadcast pattern meets the previous pass without doubling the dose.
To ensure the most uniform coverage, especially with broadcast spreaders, apply half of the calculated fertilizer amount in one direction and the remaining half in a perpendicular direction. This crisscross pattern minimizes the risk of streaking or missed spots. Turn off the flow of granules whenever the spreader stops, makes a turn, or crosses the perimeter strip, preventing a concentrated dump of material that will burn the turf.
Post-Application Steps and Cleanup
Immediate action is required after application to activate the fertilizer and safeguard the lawn. Granular fertilizers must be “watered in,” meaning thorough irrigation must follow the spreading process. This watering washes the granules off the grass blades and into the soil, where the nutrients can dissolve and be absorbed by the roots.
Failing to water immediately allows concentrated chemical salts to remain on the leaf surface, which draws out moisture and causes the characteristic brown scorch known as fertilizer burn. Water should be applied until the soil is thoroughly moist, but not enough to cause runoff, which would wash the nutrients away. A brief 20-minute watering with a sprinkler should be adequate for this initial activation.
Finally, any stray granules that landed on hard surfaces like driveways, sidewalks, or patios must be swept or blown back onto the lawn or collected for disposal. These granules left on impervious surfaces can dissolve and stain the material or be washed into storm drains, potentially polluting local waterways. The spreading equipment itself should be cleaned immediately with water to prevent corrosion and rust caused by the fertilizer salts, ensuring the spreader is ready for its next use.