A drought, marked by a prolonged lack of rainfall, quickly changes lawn care practices. Turfgrass responds to this moisture deficit by showing visible signs of stress, such as shifting from green to a dull, bluish-gray, or browning and wilting. This raises the question of whether to continue mowing. The answer is yes, but only with significant adjustments to protect the grass during its vulnerable state. Normal mowing practices can severely damage a lawn struggling to survive.
How Drought Affects Lawn Health
Turfgrass uses a defense mechanism called summer dormancy when faced with limited water. This survival strategy involves the plant intentionally stopping active shoot growth and redirecting its limited energy to protecting the roots and the crown. The crown is the small, lower section where the stem and roots meet and where new growth originates.
During dormancy, grass blades turn brown because the plant stops producing chlorophyll, but underground structures remain alive, waiting for moisture. Mowing severely stressed or fully dormant grass is dangerous because it can easily damage the sensitive crown tissue. Damaging the crown forces the plant to expend stored energy on recovery rather than survival, which prevents it from reviving once the drought ends.
A common sign of drought stress is when footprints remain compressed on the lawn after walking across it, indicating the blades lack the water pressure to spring back up. In this state, the plant is already functioning at a reduced capacity. Cutting the blades further reduces the plant’s limited surface area for energy production, compounding the stress. A stressed lawn will recover, but one whose crowns are damaged may thin out or die completely.
Mowing Adjustments During Dry Periods
The primary adjustment during a dry period is to raise the cutting deck on the mower to its highest setting. Taller grass blades provide a natural, insulating layer of shade for the soil surface, which reduces soil temperature and slows water evaporation. This helps the turfgrass conserve the small amount of moisture remaining in the soil.
Most turfgrasses benefit from a cutting height between 3 and 4 inches during drought. This greater height encourages a deeper root system, as roots generally mirror the height of the shoots above ground. Deeper roots allow the plant to access deeper pockets of soil moisture, improving resilience to drought conditions.
Mowing frequency must be drastically reduced, or halted entirely, if the grass has stopped growing and entered full dormancy. If the grass is still growing, adhere strictly to the “one-third rule.” This dictates that no more than one-third of the total blade length should be removed in a single cutting session. Removing too much leaf tissue causes a shock the stressed plant cannot absorb.
When mowing is necessary, adjust the timing to minimize stress. Mowing during the cooler parts of the day, such as early morning or late evening, is preferable to avoid midday heat. Additionally, ensure the mower blades are sharp. Dull blades tear the grass, creating ragged wounds that lose moisture more quickly and invite disease.
Managing Clippings and Fertilization Under Stress
The decision regarding grass clippings changes during a drought. Leaving the finely cut clippings on the lawn, known as grasscycling, is beneficial during dry spells. These clippings act as a light, natural mulch, aiding in shading the soil and reducing moisture loss through evaporation.
As the clippings break down, they return valuable nutrients and organic matter to the soil, supporting microbial life. Ensure the clippings are short and dispersed evenly so they do not clump together and smother the existing grass. If the grass is cut when wet or is too long, the resulting thick clumps should be raked up and removed.
Fertilization practices must be suspended during periods of drought and high heat. Applying nitrogen fertilizer encourages new leaf growth, which requires a significant amount of water to sustain. Forcing this new growth when water is scarce puts an unsustainable demand on the plant’s limited resources.
The salts in many synthetic fertilizers can also draw moisture away from the parched grass roots, resulting in “fertilizer burn.” It is best to wait to apply fertilizer until the drought has passed. Consistent moisture and cooler temperatures allow the grass to recover naturally before fertilization resumes.