A healthy, vibrant lawn requires proper nutrition, a process known as fertilization, which supplements the nutrients the soil naturally lacks. This step drives deep green color, increases turf density, and promotes strong, deep root systems. Fertilizing your lawn yourself offers greater control over the products used and can be significantly more cost-effective than hiring a professional service.
Preparing the Lawn and Determining Application Timing
The success of fertilization depends on proper timing and preparation. Optimal timing depends entirely on the type of grass you cultivate: cool-season or warm-season.
Cool-season grasses, like Kentucky bluegrass and fescue, grow most vigorously in spring and fall. These turf types benefit most from a light feeding in early spring and a heavier application in the fall, which strengthens roots before winter dormancy.
Warm-season grasses, such as Bermuda and Zoysia, thrive in the heat of late spring and summer, making this their primary feeding window. These varieties should be fertilized starting in late spring or early summer when soil temperatures consistently reach 65 to 70 degrees Fahrenheit.
Regardless of your grass type, mow the lawn a day or two before application, keeping the height slightly shorter than usual. If using a granular fertilizer, water the lawn lightly a few days prior, ensuring the soil is moist but the grass blades are dry on application day.
Before applying any product, consider a soil test to understand your lawn’s specific needs. This test provides a detailed analysis of existing nutrient levels and pH balance, allowing you to choose a fertilizer that precisely addresses any deficiencies.
Understanding Fertilizer Types and N-P-K Ratios
Choosing the correct product requires understanding the three numbers prominently displayed on every fertilizer bag, known as the N-P-K ratio. These numbers represent the percentage by weight of Nitrogen (N), Phosphorus (P), and Potassium (K), the three primary macronutrients grass requires. For example, a 20-5-10 fertilizer contains 20% nitrogen, 5% phosphate, and 10% potash by weight.
Nitrogen (N) is the nutrient most responsible for promoting rapid growth, deep green color, and a dense appearance. Phosphorus (P) supports strong root development and the establishment of new seedlings. Potassium (K) helps the grass tolerate environmental stresses, such as drought, heat, and disease. Most established lawns primarily need nitrogen, with P and K applications often guided by soil testing results.
Fertilizers are generally available in two forms: granular and liquid. Granular fertilizers are the most common choice for homeowners, offering a slow-release feed over an extended period, typically eight weeks. The granules must dissolve in water before the nutrients can be absorbed by the roots. Liquid fertilizers provide quick, immediate nutrient availability because they are absorbed through the leaves and roots almost instantly.
A third category is “weed and feed” products, which combine fertilizer with a broadleaf weed killer. While convenient, the timing required for optimal weed control often conflicts with the best time for general fertilizer application. If you opt for a weed and feed, follow the label instructions exactly, as the application method may vary from a straight fertilizer product.
Step-by-Step Guide to Fertilizer Application
Fertilizer application is best accomplished using a spreader, which ensures even coverage and prevents uneven growth patterns. The two main types are the broadcast (rotary) spreader and the drop spreader. Rotary spreaders cover a wide area by throwing granules in a circular pattern, making them ideal for large, open lawns. Drop spreaders release the fertilizer straight down, offering greater precision near garden beds and walkways.
Before filling the hopper, calibrate the spreader to the rate specified on the fertilizer bag for your specific product and spreader model. Using the wrong setting will result in over-application (leading to fertilizer burn) or under-application (yielding poor results). Start with the spreader’s flow setting closed, fill the hopper on a hard surface like a driveway, and then move to the lawn to begin spreading.
Begin by spreading a perimeter strip around the entire lawn to create a turning area. For a rotary spreader, engage any side-shield features to prevent granules from scattering onto non-turf areas. Once the perimeter is complete, walk back and forth in straight, parallel lines across the lawn, much like mowing.
Overlap each pass slightly to ensure comprehensive coverage, typically by moving over about half the distance of the spreader’s previous spread pattern. Maintain a consistent walking speed for a uniform application rate. Always close the spreader gate when turning at the ends of the pass or when stopping to prevent fertilizer from pooling and scorching the grass.
Immediate Care After Fertilization
The most important step immediately following the application of granular fertilizer is watering the lawn. Watering within 24 hours is necessary to wash the granules off the grass blades and down into the soil, where they dissolve and release nutrients. This immediate moisture also prevents the high salt content of the granules from scorching the turf (fertilizer burn).
A light, thorough watering of about 15 to 30 minutes is usually sufficient to activate the product without causing runoff. If you applied a liquid fertilizer, wait until the product has completely dried on the leaves, typically two to four hours, before watering. Waiting allows the nutrients to be fully absorbed by the foliage.
After application, sweep any fertilizer granules that landed on sidewalks, driveways, or patios back onto the lawn. This cleanup prevents the granules from running into storm drains, which can cause nutrient pollution in local waterways. Wait at least 24 to 48 hours before mowing the lawn again, and keep pets and children off the treated area for a minimum of 24 hours to allow the fertilizer to fully settle and dry.