Grass clumps are dense piles of cut grass left behind after mowing that are detrimental to lawn health. These piles smother the underlying turf, blocking sunlight and reducing the air circulation needed for healthy growth. This lack of resources can lead to the development of brown or yellow patches and increase the risk of fungal diseases. Preventing clumping involves a combination of preparing your equipment, managing your lawn’s condition, and adjusting your technique.
Essential Mower Preparation
The physical condition and setup of the lawnmower directly influence its ability to process and disperse grass clippings evenly. The sharpness of the cutting blades is primary and should be maintained regularly, typically after every 20 to 25 hours of operation. Dull blades tear the grass instead of slicing it cleanly, creating heavier clippings that are more likely to tangle and clump. This tearing also stresses the grass plant, making it more vulnerable to disease.
Cleaning the underside of the mower deck is another important task. Caked-on grass buildup disrupts the high-speed airflow created by the blades, which is necessary to lift the grass and effectively discharge clippings. Reduced airflow causes the cut material to drop immediately in dense piles rather than being dispersed thinly. For mulching mowers, ensure the deck’s baffling is clean and correctly positioned so clippings are chopped into the fine pieces needed for decomposition.
Optimizing Grass Conditions
Preventing clumps starts by ensuring the grass is in the best state for cutting. The most significant factor contributing to clumping is moisture, as wet grass blades stick together and are substantially heavier than dry ones. Mowing grass with heavy dew or after rain causes clippings to form dense, matted wads that clog the discharge chute or collect under the deck. Waiting until the grass is completely dry, often mid-morning or later, allows the mower to process the clippings more effectively.
Managing grass length using the “one-third rule” is another preventative measure. This rule suggests never removing more than one-third of the total blade height in a single mowing session. For instance, if you maintain your lawn at three inches, mow before it exceeds four-and-a-half inches. By only removing a small portion, the clippings produced are short and light enough to decompose quickly, eliminating large clumps. Adhering to this rule often requires increasing cutting frequency during periods of peak growth.
Refining Your Mowing Technique
How the operator moves the machine across the turf plays a large role in ensuring clippings are distributed rather than piled. Moving too quickly overloads the mower deck and does not allow the blades enough time to process and expel the cut material. Reducing your walking speed, especially in dense or overgrown areas, gives the mower’s airflow system the necessary time to discharge the clippings evenly and prevent clogging.
Employing overlapping passes is beneficial for a uniform cut and better clipping dispersal. Changing the direction of your mowing pattern with each cut helps prevent rut formation and ensures the clippings are spread out in different directions. When encountering thick or tall grass, raise the cutting deck to its highest setting for a first pass to remove the top portion. A second pass can then be made at the desired lower height, which reduces the volume of material processed in a single cut, lowering the chance of clumping.
Handling Existing Clippings
If clumping still occurs, cleanup is necessary to protect the lawn. The simplest approach for minor clumps is to use a leaf blower to lightly fan the piles, scattering them thinly over the turf. Spreading the clippings ensures the underlying grass receives sunlight and allows the organic matter to break down quickly, returning nutrients to the soil.
For heavier concentrations, a second, immediate pass with the mower can further chop and disperse the material. For this technique, raise the mower deck one setting higher than the initial cut to prevent overwhelming the machine. If the clumps are too large for a blower or a second pass, lightly raking them with a flexible fan rake is the final option for spreading the material or collecting them for composting.