St. Augustine grass is a popular choice for warm-climate lawns, prized for its dense, carpet-like growth and deep green color. When large patches of brown or dying turf appear, understanding the difference between stressed and truly dead grass is the first step toward successful revival. This guide will help diagnose the problem and restore your St. Augustine lawn to health.
Assessing the Damage: Is It Truly Dead?
Before initiating treatment, determine if the grass is dormant or truly dead, as revival efforts are futile on dead turf. A simple “tug test” or “scratch test” on the stolons (the runners that spread horizontally) can provide the answer. Gently tug on the brown grass blades; if they come out easily with no resistance, the roots have failed, and the grass is dead.
If the grass offers resistance, it is likely only stressed or dormant and has a chance of recovery. For a more precise check, examine the stolons by scraping the surface of a runner with your fingernail. If the tissue beneath the brown leaf blades is still white or green, the plant’s crown is alive and capable of new growth, indicating revival is possible.
Pinpointing the Cause of Decline
Effective treatment begins with understanding why the grass declined, as St. Augustine is vulnerable to specific pests and diseases that require targeted remedies. The pattern of damage across your lawn provides the best visual clues for an accurate diagnosis.
The Chinch Bug is one of the most destructive pests, causing dry, irregularly shaped patches that often appear first in the hottest, driest areas, such as along sidewalks or driveways. These tiny insects suck the sap and inject a toxin, resulting in brown patches that do not green up even after watering.
In contrast, Brown Patch fungus typically presents as distinct, circular patterns, usually one to five feet in diameter. This fungus thrives in cool, wet conditions, often appearing in the spring or fall when nighttime temperatures are below 70°F.
If the damage is widespread and uniform, the cause is often cultural stress, such as over- or under-watering, scalping the lawn with a mower set too low, or a nutrient deficiency. Improper mowing can damage the grass’s thick stolons.
Immediate Steps for Grass Revival
Once the underlying problem is identified, immediate, focused action can begin the revival process. For drought stress, the most common cultural issue, transition to a deep, infrequent watering schedule.
Apply about one to one-and-a-half inches of water per week, spread over one or two sessions, which encourages deeper root growth and better resiliency.
Watering in the early morning is best to ensure the grass blades dry quickly, minimizing conditions favorable for fungal growth. If the diagnosis points to Chinch Bugs, apply a contact insecticide containing active ingredients like bifenthrin to the affected areas and slightly beyond.
Because Chinch Bugs reproduce quickly, a second application two to three weeks later may be necessary for full eradication. For Brown Patch fungus, apply a granular or liquid systemic fungicide. Temporarily reducing watering and avoiding late afternoon or evening watering is crucial, as the fungus needs prolonged moisture to spread.
After addressing the stressor, a light application of a slow-release fertilizer can encourage new growth from the living stolons. Avoid heavy fertilization, especially with high-nitrogen products, which can worsen fungal problems or chemically burn the stressed grass.
Maintaining a Healthy St. Augustine Lawn
Preventative maintenance is the best defense against future decline, focusing on cultural practices that keep St. Augustine robust against pests and disease. Mowing height is particularly important; St. Augustine should be cut at a height between 3.5 and 4 inches.
Maintaining this height shades the vulnerable stolons and soil, which helps to conserve moisture and suppress weed growth. Continue deep and infrequent watering, soaking the turf only when the grass shows the first signs of wilting.
This technique trains the roots to grow deeper, making the plant more resilient to dry periods and heat. Fertilization should be timed seasonally, typically in late spring or early summer and again in the early fall, using a slow-release formula for consistent nutrition.
Regularly monitor your lawn for early signs of stress, especially in hot, sun-exposed areas where Chinch Bugs often begin damage. Adhering to these cultural practices ensures your St. Augustine lawn maintains the vigor needed to fight off common threats that cause decline.