Overwatering a lawn is a common mistake that can be just as damaging as drought. When excess water is applied, it fills the pore spaces in the soil, displacing the oxygen that grass roots require to survive. This lack of oxygen effectively suffocates the roots, leading to stress and eventual death of the plant tissue. Overwatered grass develops a shallow, weak root system because the roots remain near the surface where oxygen is still available.
Primary Symptoms of Overwatering
The most observable sign of overwatering is the texture of the soil, which will feel soft, squishy, or spongy underfoot. Walking across the lawn may leave distinct footprints that remain visible for an extended period, indicating the soil is not draining properly. Visible signs of standing water or runoff onto hardscaped areas immediately after irrigation also confirm the soil is saturated past its absorption capacity.
The grass blades may initially appear lush and vibrant, but they quickly become limp and lose their vitality. This is followed by a distinct yellowing, or chlorosis, which also occurs with drought stress. The yellowing from overwatering happens because the excess water leaches away essential nutrients, such as nitrogen. Furthermore, the lack of oxygen prevents the roots from absorbing the remaining nutrients. Unlike drought stress, the overwatered grass is limp, and the soil beneath is damp.
Secondary Damage Caused by Excess Moisture
Prolonged soil saturation creates an ideal environment for various biological threats that cause significant secondary damage. The constant wetness encourages the growth of fungal pathogens, leading to common turf diseases such as Brown Patch, Dollar Spot, and Pythium blight. Brown Patch thrives in hot, humid conditions when the turf remains wet for extended periods, creating irregular circles of damaged grass.
Dollar Spot is characterized by small, bleached spots and is exacerbated by excessive moisture and high humidity. The lack of oxygen also leads to root rot, which is the internal breakdown of the root system. Root rot prevents the grass from taking up water and nutrients, ultimately causing the plant to die. The constantly damp soil also attracts specific pests, including fungus gnats and certain types of harmful nematodes.
Immediate Steps to Reverse Overwatering
The most immediate action when overwatering is suspected is to completely stop all irrigation until the soil has an opportunity to dry out significantly. The soil should be allowed to dry down to a depth of at least two to three inches before any water is reintroduced. This pause allows the soil’s pore spaces to refill with oxygen, which is necessary for the surviving roots to begin recovery.
To hasten the drying process and improve oxygen flow, mechanical aeration is highly beneficial, as it alleviates the soil compaction caused by the excess water. Using a core aerator to create small holes across the lawn allows air to penetrate deep into the root zone, improving drainage and strengthening the roots. For areas with severe pooling, improving localized drainage or applying a thin layer of compost can enhance the soil structure and absorption capabilities.
Once the soil has dried, water should be reintroduced with a deep and infrequent schedule to encourage the development of deep, resilient roots. Aiming for about one inch of water per week, factoring in natural rainfall, is a common goal for established lawns. Watering early in the morning is preferable, as this allows the grass blades to dry completely before nightfall, minimizing the surface moisture that encourages fungal growth.