Killing grass, often referred to as “drying it out,” is a strategy used to eliminate turf and unwanted vegetation completely, often to prepare an area for new landscaping. This permanent elimination is typically achieved through desiccation (extreme moisture removal), nutrient deprivation, or thermal stress. Effective grass removal is about interrupting the plant’s fundamental biological processes, such as photosynthesis and nutrient uptake, ensuring the root system cannot recover.
Killing Grass Using Solarization and Heat
One highly effective, non-chemical method relies on thermal stress known as solarization, which utilizes the sun’s energy to superheat the soil. This technique requires covering the area with clear plastic sheeting, typically 2 to 6 mil thick, to create a concentrated greenhouse effect. The clear plastic traps sunlight, raising the temperature of the topsoil to levels lethal to grass, seeds, and even some pathogens.
Before laying the plastic, the area should be watered thoroughly, as moist soil conducts and retains heat more effectively than dry soil. The edges of the plastic must be completely sealed by burying them in a trench or weighing them down to prevent heat from escaping. For the process to be successful, the soil temperature in the top six inches must consistently reach 110° to 140°F. This thermal death usually takes between four and eight weeks during the hottest, sunniest part of the year.
Smothering Grass by Blocking Light
Another non-chemical strategy focuses on depriving the grass of the light necessary for photosynthesis, a process called occultation. By completely blocking this light source, the plant exhausts its stored energy reserves and eventually dies, leading to desiccation.
This method involves covering the grass with an opaque barrier, such as thick black plastic tarps, heavy cardboard, or multiple layers of newspaper. The material must be secured tightly to the ground to ensure zero light penetration and left in place for an extended period. Because this technique relies on starvation rather than intense heat, it works more slowly than solarization, typically requiring six weeks to several months for complete root death. The use of dense, biodegradable materials like cardboard can also provide the benefit of breaking down into soil organic matter, improving the bed for future planting.
Applied Methods of Desiccation
For immediate results, the application of external substances offers a quicker path to grass death through active desiccation. Chemical options include broad-spectrum, non-selective herbicides, which work systemically by being absorbed through the leaves and translocating throughout the entire plant, including the root structure. Following all manufacturer instructions and wearing appropriate safety gear is necessary when handling these chemicals.
Natural desiccant alternatives rely on caustic compounds to rapidly strip moisture from the plant tissue. Concentrated horticultural vinegar, which contains acetic acid at levels of 10 to 45 percent (far higher than household vinegar), acts as a contact herbicide. It quickly disrupts plant cell membranes, causing the foliage to burn and dry out within hours of application. High concentrations of acetic acid are corrosive, requiring protective eyewear and gloves during use.
A less common, but effective, natural approach involves using high concentrations of salt, such as sodium chloride, to induce severe osmotic stress. The salt pulls water out of the grass roots and tissue, leading to dehydration and death. However, this method carries a significant risk because salt does not readily break down and can remain in the soil for years, severely altering the soil’s structure and rendering the area infertile for future planting.