Horticultural vinegar, a concentrated form of acetic acid, is a non-selective contact herbicide that can kill grass. The short answer is yes, but its effectiveness depends on the product’s concentration and how it is applied. Horticultural vinegar is specifically formulated to be potent enough to destroy plant tissue, unlike the common vinegar found in kitchen cabinets.
Horticultural Vinegar vs. Household Vinegar
The effectiveness of any vinegar-based product as a herbicide depends entirely on its acetic acid concentration. Standard household white vinegar, used for cooking and cleaning, contains about 5% acetic acid. This low concentration has limited effectiveness in killing mature grass or established weeds, often causing only minor surface burn to the foliage. Horticultural vinegar is a specialized product with significantly higher concentrations, often ranging from 20% to 30% acetic acid. This difference in strength transforms the mild kitchen ingredient into a viable herbicide, allowing the solution to rapidly destroy plant cells on contact.
How Acetic Acid Destroys Plant Cells
The mechanism by which concentrated acetic acid kills grass is through a process called desiccation, or rapid drying. Acetic acid acts as a non-selective contact herbicide, meaning it causes damage only to the plant tissue it directly touches. The acid penetrates the waxy outer layer of the grass blade, called the cuticle, and quickly dissolves the integrity of the plant’s cell membranes. Once compromised, the acetic acid draws moisture out of the plant cells. This rapid dehydration leads to the collapse of the cell walls and the visible “burning” or browning of the foliage, often within hours. Since this process is non-selective, it destroys any green plant tissue, including both unwanted grass and desirable plants.
Practical Application and Treatment Limitations
For horticultural vinegar to effectively kill grass, it must be applied directly to the unwanted foliage to ensure complete coverage. The best results are achieved when the product is sprayed on a hot, dry, and sunny day. Sunshine and warmth accelerate the desiccation process, helping the acetic acid work quickly before it can be diluted by rain or morning dew.
A major limitation of using horticultural vinegar is its contact-only mode of action; it does not translocate systemically down to the plant’s root system. While the above-ground part of the grass is quickly destroyed, the roots of perennial grass or deep-rooted weeds often remain intact. The plant frequently regrows from the unaffected root crown, requiring repeated applications to manage new growth. For this reason, concentrated acetic acid is most effective on young, small annual grasses with shallow root systems.
Safety and Environmental Considerations
Handling horticultural vinegar (20% or higher acetic acid) requires significant safety precautions due to its highly corrosive nature. The concentrated acid poses a serious risk of chemical burns to the skin and can cause permanent damage, including blindness, if it contacts the eyes. Product labeling often carries a signal word like “DANGER” because of these risks.
Appropriate personal protective equipment is necessary when handling and applying the solution. This includes wearing protective splash goggles or a face shield, chemical-resistant gloves, and long-sleeved clothing to prevent skin exposure. Additionally, inhaling the vapors or mist may cause irritation to the respiratory tract and mucous membranes.
From an environmental standpoint, acetic acid breaks down rapidly, preventing long-term residue buildup in the soil. However, the high acidity can temporarily lower the soil’s pH in the treated area. This pH change could affect the growth of future plantings, particularly if the product is used extensively.