Homeowners often worry about accidental grease spills, whether from a barbecue or a vehicle, damaging their lawn. A concentrated spill of grease or oil will quickly damage and ultimately kill turfgrass. This damage occurs through a physical and biological disruption of the plant’s essential life processes, not a chemical burn. The severity of the damage depends directly on the type and volume of the grease spilled.
The Immediate Impact of Grease on Grass
A substantial grease spill, especially if hot, causes immediate and visible injury to the lawn. Within hours, the grass blades in the affected area will wilt and discolor, turning a dark green before transitioning to yellow or brown. This rapid decline occurs because the grease forms a hydrophobic, or water-repelling, film over the plant tissue.
The physical coating prevents the plant from performing respiration and transpiration. The grass is effectively suffocated as the grease blocks the tiny pores on the leaf surfaces, known as stomata. These pores are necessary for the exchange of gases like carbon dioxide and oxygen. The resulting dead patch of grass often appears greasy and matted down.
How Grease Damages Plant Life and Soil
The damage extends beyond the visible leaf blades, impacting the entire plant structure and the surrounding soil environment. Grease coats the stem and root systems, stopping the absorption of water and dissolved nutrients from the soil. This blockage leads to internal dehydration and starvation, accelerating the plant’s demise.
In the soil, the grease spill creates an impenetrable layer that disrupts the balance necessary for healthy growth. The hydrophobic layer prevents oxygen from reaching the roots, impeding root respiration. It also inhibits the activity of beneficial soil microorganisms. These microbes break down organic matter and cycle nutrients, and their suppression can effectively sterilize the immediate area.
The composition of the grease influences the extent of the soil damage. Cooking grease is organic and will eventually be broken down by soil bacteria, though slowly due to oxygen deprivation. Mineral oils, such as motor oil, present a greater problem because they contain toxic, persistent hydrocarbon compounds that cause long-term soil contamination. In either case, the soil structure is compromised, becoming less permeable and unable to support new turf growth until the grease is removed or degraded.
Practical Steps for Cleaning Up a Grease Spill
Immediate action is necessary to minimize damage and prevent the grease from migrating further into the soil. First, gently blot the wet area with absorbent materials like old towels or paper towels. Be careful not to rub or spread the grease deeper into the turf. Avoid using high-pressure water, which pushes the contaminant down into the root zone.
After removing the bulk of the liquid, apply a generous layer of an absorbent powder over the spill area. Materials like cat litter, cornmeal, or sawdust work well to draw out the remaining residue from the grass and topsoil. Allow the absorbent material to sit for several hours to fully saturate, then carefully sweep it up and dispose of it.
To treat the remaining residue, apply a small amount of liquid dish soap—a known degreaser—mixed with water. The soap acts as an emulsifier, breaking the grease into smaller droplets that can be rinsed away. Use a standard dish soap, not an antibacterial one, as the latter can harm the beneficial soil microbes needed for recovery.
For spills that have caused deep, severe damage, the most effective remediation is soil replacement. This involves carefully cutting out the dead grass and removing the top four to six inches of contaminated soil. The excavated area should then be filled with fresh topsoil before reseeding or laying new sod.