Mowing a lawn requires specific conditions for the best results. When grass is wet, typically from heavy morning dew or recent rainfall, it becomes heavier and more pliable, changing how it interacts with a mower’s blade. This moisture-laden state makes cutting the lawn inefficient and potentially damaging to both the turf and the equipment. Turf management professionals advise against mowing wet grass to preserve the health of the lawn and the longevity of the machine.
Damage to Grass Health
Cutting wet grass compromises the health and appearance of the turf because moisture causes blades to bend instead of standing upright. The mower blade tears the wet, pliable grass rather than slicing it cleanly, resulting in ragged, open wounds on the tips. These torn tips quickly dry out and turn brown, giving the lawn a dull, unhealthy appearance.
The presence of moisture and open wounds creates an ideal environment for fungal diseases. Fungal spores, such as those causing brown patch or dollar spot, thrive in damp conditions and spread easily via the mower’s deck and wheels. Wet grass clippings tend to clump into dense mats deposited onto the lawn, which can smother healthy grass and cut off sunlight and air circulation. These clumps act as an incubator for mold and disease, intensifying the risk of turf infection.
Strain on Mowing Equipment
Wet grass increases the mechanical strain placed on the mower’s engine and cutting components. The heavier, denser wet clippings quickly accumulate and stick to the underside of the mower deck, leading to clogging of the discharge chute. This clogging disrupts the airflow that lifts the grass for a clean cut, forcing the engine to work harder to rotate the blade through the stuck material.
This resistance puts stress on the engine or motor, potentially leading to overheating or premature component wear. The constant friction against the wet mass causes the blades to dull faster than when cutting dry grass, exacerbating the tearing effect on the turf. Leaving wet grass residue caked on the deck invites rust and corrosion, compromising the structural integrity and lifespan of the equipment.
Operator Safety Risks
Mowing wet grass introduces several hazards due to reduced traction and slippery conditions. Wet grass underfoot increases the risk of slipping, especially when mowing on slopes or making sharp turns, which can lead to a loss of control or a fall near the moving blades. The mower wheels can lose traction and slide, particularly on inclines, increasing the potential for accidents.
Wet clippings stick together more firmly and are expelled with greater mass than dry clippings, increasing the danger of discharged projectiles. For operators using corded electric mowers, wet conditions pose a risk of electrical shock. Water and electricity are a dangerous combination, making it unsafe to handle a corded machine on any damp surface.
Mitigation and Timing Strategies
If a delay is impossible due to overgrowth or scheduling constraints, certain strategies can help mitigate the damage caused by cutting damp grass. The best approach is to wait until the morning dew has evaporated, typically until late morning or early afternoon when the grass is driest. If the grass must be cut while damp, ensure the mower blades are razor-sharp to maximize the chance of a clean slice rather than a tear.
The cutting height should be raised slightly higher than normal to reduce the volume of wet material the mower has to process. Moving the mower at a slower pace allows the blade more time to cut the heavier grass and reduces the strain on the engine. Frequent cleaning of the underside of the mower deck during the process is necessary to prevent build-up and clogging.