Dew is condensation that forms on grass blades when temperatures drop and humidity is high, usually overnight. While it might seem convenient to mow early, cutting turf saturated with moisture is strongly discouraged by turf management experts. This practice introduces biological, mechanical, and safety concerns that affect both the lawn’s quality and the equipment’s lifespan.
Why Mowing Wet Grass is Problematic
Water droplets add weight and flexibility to individual grass blades, causing them to bend and stick together rather than standing upright. When the mower blade passes over the lawn, it pushes these moist, clumped blades down instead of providing a clean, vertical cut. This results in an uneven and ragged appearance, leaving many blades partially uncut and folded over. The high moisture content also increases friction, demanding more effort from the cutting mechanism and hindering the natural dispersal of clippings back into the soil.
Damage to Turf Health
Mowing saturated turf compromises the plant’s natural defense mechanisms by damaging the individual grass blades. Instead of a clean slice, the wetness often leads to a tearing or shredding action, leaving the grass with open, jagged wounds. These ragged edges take longer to heal and present a whitish or brownish appearance on the lawn surface. The presence of excess moisture combined with fresh wounds dramatically increases the lawn’s susceptibility to fungal infections like brown patch or dollar spot.
When wet clippings are discharged from the mower, they form heavy, dense clumps that settle directly onto the turf. These wet mats block sunlight and air circulation, effectively smothering the grass underneath. If not quickly removed, these clumps cause localized yellowing and death of the underlying turf. The physical act of walking or rolling the mower over saturated soil also leads to compaction, which restricts the movement of water and oxygen to the root zone.
Risks to Mower Function and Safety
Wet clippings are heavy and sticky, quickly building up inside the mower deck and chute. This accumulation drastically reduces the air vacuum necessary for the blades to lift the grass effectively, leading to poor cutting performance and clumping. The reduced efficiency forces the engine to work harder to maintain blade speed, placing undue stress on the motor and shortening its service life.
Continuous exposure to moisture accelerates wear and tear on the metallic components of the mower. The combination of wet plant matter and fresh cuts can cause accelerated rust and corrosion, particularly on the cutting blades and internal deck surfaces. Sharpened blades lose their edge more quickly when consistently exposed to moisture and the heavier load of wet grass.
Mowing on dew-covered grass introduces safety hazards for the operator. The wet turf provides poor traction, increasing the risk of slipping, especially when maneuvering on slopes or uneven terrain. If the deck becomes severely clogged, the sudden resistance can lead to engine kickback or stalling, which compromises the operator’s control.
Optimal Timing for Mowing
The best time for turf maintenance is when the grass blades are completely dry and standing upright. This typically means waiting until mid-morning or early afternoon after the sun has evaporated the overnight moisture completely. A simple method to check the lawn’s readiness is the “foot test”; if walking across the lawn leaves dark, wet tracks, it is advisable to wait longer.
It is also important to avoid mowing immediately after a significant rainfall event, as saturated soil and turf pose the same problems as heavy dew. While mowing in the late afternoon is acceptable, avoid the late evening when temperatures begin to drop and conditions favor dew formation.