Bermuda grass is a warm-season turf known for its dense, vibrant growth, but it requires precise timing for its annual weed and feed cycle. This turf enters winter dormancy, turning brown until soil conditions are right for spring green-up. Successful lawn care hinges on synchronizing fertilizer and herbicide applications with exact soil temperatures, rather than following calendar dates. Understanding these temperature triggers ensures the products are effective and the grass is supported during its most active growth phases.
Waking Up Bermuda Grass: Early Spring Timing
The first actions of the year are dictated by the warming ground, signaling the transition out of winter dormancy. Bermuda grass begins to show signs of life when the soil temperature consistently reaches 60 to 65 degrees Fahrenheit at a four-inch depth. This temperature is the cue to start a light feeding schedule to gently encourage the turf out of its winter sleep.
The most time-sensitive action in early spring is the application of the first pre-emergent herbicide, which creates a chemical barrier in the soil. This treatment must be applied before summer annual weed seeds, such as crabgrass, begin to germinate. Crabgrass germination typically opens when soil temperatures reach 53 to 58 degrees Fahrenheit for several consecutive days. Timing the application before this threshold is reached is paramount for season-long control.
Applying a product containing an active ingredient like prodiamine too early will cause the protective barrier to degrade before the weed seeds sprout, wasting the material. Conversely, waiting until the soil warms past 65 degrees means the weeds have already germinated, rendering the pre-emergent ineffective. Tracking local soil temperatures daily is the most reliable method to ensure accurate placement of this initial weed control.
The first feeding should occur shortly after the initial green-up begins, using a low-nitrogen, balanced fertilizer to ease the grass into growth. A formula with a ratio close to 3-1-2, such as a 12-4-8 blend, provides the necessary nutrients without shocking the roots with overwhelming nitrogen. This initial light meal supports immediate recovery and provides a foundation for the vigorous growth period that follows.
Summer Maintenance: Sustained Feeding and Weed Control
The summer months represent the high-demand period for Bermuda grass, which thrives in heat and requires an aggressive feeding regimen to maintain density and color. This turfgrass can utilize a significant amount of nitrogen, requiring up to four to five pounds of actual nitrogen per 1,000 square feet annually. This total is divided into frequent applications throughout the active growing season.
The feeding schedule should involve applying a high-nitrogen, slow-release fertilizer every four to eight weeks, depending on the specific product and desired growth rate. Formulas with a high first number, such as 20-0-10, provide the fuel needed for rapid shoot growth and recovery from wear. Consistency is necessary because the grass is actively growing and quickly consuming available nutrients in the soil.
Despite pre-emergent efforts, some broadleaf weeds will inevitably penetrate the barrier, requiring a different approach. Post-emergent herbicides are used to treat weeds that have already sprouted and are applied directly to the foliage. These products are reactive, meaning they are applied only when weeds are visible.
Careful attention to temperature is necessary when applying post-emergent herbicides to avoid damaging the Bermuda turf. Applications should not be made when temperatures exceed 90 degrees Fahrenheit, as the combination of the herbicide and extreme heat can lead to chemical burn on the grass blades. The best time for spot treatments is typically in the early morning or late evening when the air is cooler and the grass is not under heat stress. These applications require moisture to be effective, so the lawn should be adequately watered a day or two before application and the product watered in according to label instructions.
Preparing for Dormancy: Fall Applications
As summer heat subsides and the days shorten, the focus shifts from growth stimulation to preparing the turf for winter survival. This requires a gradual change in the fertilizer composition to fortify the plant’s defenses. The final high-nitrogen application of the season should be completed approximately four to six weeks before the first expected hard frost date.
The final feeding of the year must prioritize root strength and cold tolerance over green color and shoot growth. This is achieved by switching to a high-potassium, low-nitrogen fertilizer, often called a winterizer. A formula such as 5-10-30 or a straight potash product like 0-0-25 provides the potassium needed to thicken cell walls and encourage root development, helping the grass withstand winter stress.
The second pre-emergent application of the year is timed for the fall to prevent cool-season weeds from germinating. These winter weeds, most notably Poa annua (annual bluegrass), begin to sprout when soil temperatures fall back below 70 degrees Fahrenheit. Applying a pre-emergent at this time establishes a protective layer that controls these weeds throughout the cooler months.
Missing this fall application window allows winter weeds to germinate and establish themselves, where they will be visible and disruptive as the Bermuda grass enters its brown, dormant state. Once the grass has turned completely brown after a hard frost and entered full dormancy, all feeding and chemical applications should cease. The turf will not absorb the nutrients or chemicals effectively, and the products could be wasted or potentially harm the dormant grass.