Fertilizing a lawn gives the grass the necessary elements to develop strong roots, thick blades, and a vibrant green color. These applied nutrients help the turf resist environmental stressors, disease, and the encroachment of weeds, leading to a healthier, more resilient yard. Successfully feeding your lawn requires careful selection of the product, precise timing, and an accurate application technique. Understanding these steps ensures the fertilizer is used efficiently, promoting vigorous growth without risking damage. This guide focuses on the practical methods for applying fertilizer correctly to achieve a consistently lush, healthy lawn.
Selecting the Appropriate Fertilizer
Choosing the right fertilizer starts with understanding the three numbers displayed on the bag, known as the N-P-K ratio. These numbers represent the percentage by weight of Nitrogen (N), Phosphorus (P), and Potassium (K) in that order. Nitrogen promotes vigorous leaf growth and color; phosphorus is essential for root development; and potassium enhances the grass’s stress tolerance and hardiness. A general spring or summer fertilizer might have a high nitrogen ratio, such as 25-5-5, to encourage green-up.
Fertilizer products are also categorized by how quickly their nutrients become available to the grass, either as quick-release or slow-release formulas. Quick-release nitrogen, which is water-soluble, offers an immediate visual greening effect, but it carries a higher risk of burning the grass if over-applied. Slow-release products, often coated granules, provide a sustained supply of nutrients over several weeks or months, maintaining consistent growth with a lower risk of chemical burn. Granular fertilizers, which are dry pellets applied with a spreader, are typically more cost-effective and have a longer shelf life compared to liquid options. Liquid fertilizers offer immediate nutrient delivery and are often used as starter fertilizers or for quick nutrient boosts, but they require careful application to avoid over-concentration.
Optimal Timing and Pre-Application Steps
The best time to apply fertilizer is when your specific type of grass is actively growing, which varies depending on whether you have a cool-season or warm-season lawn. Cool-season grasses, like Kentucky bluegrass and fescue, grow mainly in the spring and fall, making those the ideal application windows. Conversely, warm-season grasses, such as Bermuda and Zoysia, thrive in heat and should be fertilized in the late spring or early summer when their growth is most dynamic. Applying fertilizer outside of these active growth periods can be ineffective or stimulate tender growth susceptible to frost damage.
Before spreading any product, the lawn should be mowed to its regular height a day or two prior to application. Granular fertilizer must be applied to a dry lawn so that the particles do not stick to the grass blades, preventing them from reaching the soil and increasing the risk of leaf burn. Determine the correct application rate based on your lawn’s square footage and the product instructions. The final preparation step is calibrating your spreader, which means adjusting the flow rate mechanism to match the setting recommended on the fertilizer bag.
Spreader calibration is necessary because settings can vary significantly between different spreader models and fertilizer formulations. If a suggested setting is not provided, start with the mechanism about one-third open and test the output over a small, measured area. For the most accurate application, choose a spreader setting that delivers half the total required rate. This halved rate allows you to make two passes over the lawn in perpendicular directions, ensuring maximum coverage uniformity and eliminating skips or missed areas.
Technique for Even Application
Achieving an even application requires a methodical approach, beginning with establishing a border strip around the perimeter of the lawn. This initial pass, known as the header strip, should be applied at the half-rate setting and serves as a turnaround area. This border ensures that the edges receive coverage without over-applying fertilizer during the turns. The main application should then be performed by walking in straight, parallel lines across the lawn.
Maintain a consistent walking speed throughout the entire application, as variations in speed will directly affect the amount of fertilizer distributed. With a rotary spreader, which throws the product in a wide arc, carefully overlap each pass to cover the area missed between the throws. The wheel track from your current pass should align with the visible outer edge of the fertilizer pattern from the previous pass to ensure seamless coverage. When using a drop spreader, the technique is simpler, requiring you to align the edge of the spreader with the track of the previous pass to prevent gaps.
The most effective technique for uniformity is the “half-rate, two-pass” method. After completing the first pass over the entire lawn in one direction, load the spreader with the remaining half of the product and apply it by walking in lines perpendicular to the first set. This cross-hatch pattern compensates for minor misses or overlaps from the first application, resulting in a uniform distribution of nutrients. Always close the spreader gate when you stop walking or when turning at the end of a row to prevent fertilizer from dumping in a concentrated spot, which causes grass burn.
After the entire lawn area has been covered, sweep or blow any fertilizer granules that have landed on sidewalks, driveways, or patios back onto the lawn. This cleanup is necessary because fertilizer left on hard surfaces can be washed into storm drains, introducing excess nutrients into local waterways and potentially leaving rust-like stains on the pavement. Ensuring the product is only on the grass where it is needed is a step in both application accuracy and environmental stewardship.
Essential Post-Fertilization Care
Immediate watering is necessary, particularly when using a granular fertilizer, to activate the nutrients and move them into the soil. Watering serves to dissolve the granules and wash the fertilizer off the grass blades, which reduces the risk of “fertilizer burn” where the salts dehydrate the leaf tissue. A light but thorough watering immediately following the application is sufficient to initiate this process, helping the roots absorb the new nutrients.
After watering, keep pets and children off the treated lawn until the product is completely dry and has settled into the soil. For granular products, this waiting period is typically until the surface is dry to the touch, which can take anywhere from a few hours up to 72 hours, depending on weather conditions. Liquid fertilizers dry faster, often within a few hours. Following the application, the spreader should be thoroughly cleaned to prevent corrosion from the fertilizer salts, ensuring the equipment remains in good working order.