Fertilizing a lawn in Houston supports the rapid growth of warm-season grasses throughout the long Gulf Coast growing season. Houston’s sustained heat and humidity demand a specific, multi-step nutritional strategy, unlike cooler climates. Correct timing ensures the grass absorbs nutrients efficiently, preparing it to withstand intense summer stress and transition into winter dormancy. This tailored approach maximizes turf health against the region’s distinct environmental conditions.
Understanding Houston’s Lawn Needs
Houston’s subtropical climate features a long, warm growing season, high humidity, and heavy clay or alkaline soil. These conditions define the needs of local turf, which consists primarily of warm-season varieties like St. Augustine and Bermuda grass. These grasses thrive between 75 and 90 degrees Fahrenheit but enter dormancy during the cooler late fall and winter months.
The dense, slow-draining clay or high \(\text{pH}\) alkaline soil can lock up nutrients, making them unavailable to grass roots. The fertilization schedule must supply nitrogen for top growth, manage soil chemistry, and support deep root development before summer. The goal is to feed the grass when it is actively growing and can use the nutrients quickly.
The Critical Timing for Fertilization
The fertilization schedule is divided into three distinct periods aligning with the grass’s growth cycle.
Spring Application
The first application should occur in the spring, once the grass has broken dormancy and been mowed at least once or twice. This typically happens when soil temperatures reach 65 degrees Fahrenheit, usually in late March or early April. This initial feeding helps the turf recover from winter and encourages robust root growth before the summer heat. Applying fertilizer too early, before active growth begins, leads to nutrient runoff and waste.
Summer Application
The second application supports the turf through the peak growth period, usually between June and July. This mid-season feeding is important because high temperatures accelerate nutrient use and quickly deplete soil reserves. Summer feeding sustains the dense leaf growth needed to shade the soil and improve tolerance to drought and heat stress. Bermuda grass, a heavy feeder, may require a lighter application every four to eight weeks throughout the summer to maintain color and density.
Fall Application
The final application is performed in late summer or early fall, typically late August through September, serving as a winterizing treatment. This feeding shifts the grass’s energy away from top growth toward building carbohydrate reserves in the root system and stolons. This strengthens the plant’s underground structures, improving resilience against winter cold and ensuring a faster spring green-up. Nitrogen application should stop four to six weeks before the first expected frost, as applying it after mid-September can stimulate tender new growth susceptible to cold damage.
Selecting the Right Fertilizer
Fertilizer choice is guided by the N-P-K analysis, which represents the percentage of Nitrogen, Phosphate, and Potash. For warm-season grasses, a general \(\text{4-1-2}\) ratio is often recommended if a soil test is unavailable, such as a \(\text{16-4-8}\) or \(\text{15-5-10}\) blend. Nitrogen (\(\text{N}\)) promotes above-ground growth, Phosphorus (\(\text{P}\)) supports root development, and Potassium (\(\text{K}\)) aids in overall plant health and stress tolerance.
A slow-release nitrogen source is recommended, especially during hot summer months. These fertilizers are coated, allowing nutrients to dissolve gradually over weeks or months. This controlled release minimizes the risk of fertilizer burn common with quick-release products in intense heat, providing consistent feeding. This steady supply also supports deeper root growth, helping the lawn manage drought periods.
Iron deficiency is common in Houston’s alkaline soil, causing a yellowing, or chlorotic, appearance even when nitrogen levels are adequate. Iron supplements, often chelated for better absorption, are frequently necessary to achieve a deep green color. These treatments are helpful in late summer or early fall to maintain color without encouraging excessive top growth before dormancy.
Application Best Practices and Watering
Proper application ensures the fertilizer is distributed evenly and safely, preventing localized burning of the turf. Before spreading granular fertilizer, the lawn should be dry so granules do not stick to the grass blades. Mowing the lawn to the recommended height before application also exposes the soil surface for better contact.
Using a calibrated spreader (rotary or drop type) is necessary to apply the exact amount recommended on the product label. Over-application leads to fertilizer burn, where high salt concentration draws water out of the grass. Applying half the recommended rate in two perpendicular passes across the lawn ensures complete and uniform coverage.
Watering immediately after applying granular fertilizer activates the nutrients and washes granules off the grass blades into the soil. A light watering of about one-quarter inch is sufficient to dissolve the granules and move them to the root zone, preventing leaf burn. If using a liquid fertilizer, wait a few hours before watering to allow the product to be absorbed through the foliage.