When turfgrass faces a prolonged lack of water, it enters a state of drought stress, which triggers a defense mechanism to slow growth and conserve energy. This process can lead to dormancy, where the green leaf tissue turns brown to protect the plant’s crown and root system. Mowing a lawn under these conditions presents a dilemma: normal cutting practices can inflict damage that the stressed plant cannot overcome. Understanding the grass’s current state of health is necessary to decide on the appropriate course of action, which involves careful adjustments to technique and timing.
Assessing Grass Condition Before Mowing
The first step before bringing out the mower is to determine if the turf is actively growing or has entered a protective dormant state. A simple method to check for early drought stress is the footprint test, where you walk across the lawn. If your footprints remain visible on the grass for more than a few seconds, the grass blades lack turgor pressure and are wilting, indicating a high degree of stress.
Another early symptom of dehydration is a change in the turf’s color, which may shift from a vibrant green to a dull, grayish-blue hue. If the grass is still primarily green but showing signs of stress, reduce mowing frequency significantly, perhaps to once every two to three weeks, as growth will be minimal. The most important rule during a drought is to never mow grass that is completely brown and crisp, as this signifies full dormancy.
Mowing dormant turfgrass can irreparably damage the plant’s crown, which is the growing point located near the soil surface. The grass will already have stopped actively producing new leaves to survive the extended dry period, and the mechanical trauma from the mower can kill the plant entirely. Limiting all traffic, including that from a mower, is the safest way to ensure the plant survives until rainfall returns.
Adjusting Cutting Height for Drought Stress
If the grass is still growing slowly and a cut is deemed necessary, raising the mower’s cutting deck is a powerful technique to aid the stressed turf. Experts generally advise raising the cutting height to the highest possible setting, often between three to four inches, depending on the grass species. This adjustment promotes a greater leaf area for the plant to perform photosynthesis, producing the energy needed to survive and recover from stress.
The longer blades of grass also offer a physical defense by providing shade to the soil surface. This shading keeps the soil cooler, which directly reduces the rate of water evaporation. By lowering the soil temperature, the grass helps conserve the limited moisture available, making the lawn more resilient.
A higher cut also supports a deeper root system, allowing the plant to access water deeper within the soil profile. The fundamental “one-third rule” of mowing—never removing more than one-third of the blade length in a single cut—becomes even more important during a drought. Violating this rule removes too much of the plant’s photosynthetic capacity, forcing it to expend stored energy reserves better used for drought survival.
Managing Clippings and Timing the Cut
Managing the grass clippings correctly provides a significant advantage to a drought-stressed lawn. Instead of bagging the clippings, they should be left on the turf to decompose, a practice known as mulching. These small pieces of organic matter act as a light protective layer, further shading the soil and helping to lock in moisture by reducing water loss from evaporation.
Grass clippings are composed of 80 to 85% water and contain essential nutrients like nitrogen, phosphorus, and potassium. As they break down, they return these nutrients and moisture to the soil, functioning as a natural, slow-release fertilizer that helps the turf maintain health. For the mulching to be effective, ensure the clippings are very small and spread evenly, which requires the mower blade to be sharp.
The timing of the cut is also a factor in minimizing stress on the plant. Mowing should generally be avoided during the hottest part of the day, typically between 10 a.m. and 4 p.m. When temperatures are highest, the grass is already struggling with heat and moisture loss, and the added trauma of cutting can be detrimental.
The optimal time to mow a drought-stressed lawn is during the late afternoon or early evening, between 4 p.m. and 6 p.m. Mowing at this time allows the grass to recover from the injury during the cooler evening hours before nightfall, which reduces the risk of fungal infections. Conversely, mowing in the early morning while dew is still present can tear the grass blades and encourage disease, while also leading to clumping clippings that can smother the turf.