If you are considering using lemon juice as a natural weed killer, the short answer is that yes, it can severely damage or kill lawn grass under the right conditions. This common remedy acts as a non-selective herbicide, meaning it will harm any plant it touches, including desirable turfgrass. The destructive effect is purely chemical, relying on the acidic nature of the citrus fruit to break down plant tissue. Lemon juice is not a targeted solution and must be applied with caution to avoid destroying patches of your lawn.
How Citric Acid Affects Plant Life
Lemon juice contains a high concentration of citric acid, a weak organic acid that is the primary agent responsible for its herbicidal properties. When applied directly to grass blades, the low pH (typically around 2.2) acts as a contact poison that rapidly disrupts the cellular structure of the plant. This extreme acidity breaks down cell walls and membranes on contact, initiating a process known as desiccation. Desiccation is rapid dehydration, where the acidic solution draws moisture out of the plant’s cells, causing them to leak their contents and leading to immediate “burning” or browning. Because the acid does not move through the plant’s vascular system, it is classified as a contact herbicide.
Practical Results on Lawn Grass
The observable outcome on a lawn is highly dependent on both the concentration and the application method used. Full-strength lemon juice or a concentrated application will cause visible browning and wilting of the grass blades within hours, especially on warm, sunny days when desiccation is accelerated. This non-selective effect means that a spray directed at a broadleaf weed will also destroy the surrounding turfgrass. While the foliage damage is immediate and striking, the effect is often superficial on established turf. Since lemon juice is not a systemic herbicide, deep-rooted perennial grasses or weeds will often survive the top-growth damage and eventually regrow, resulting in a temporary cosmetic fix rather than permanent eradication.
Long-Term Soil Consequences
Repeated or large-scale application of lemon juice introduces a substantial amount of acid into the soil, altering the delicate chemical balance of the environment. The most significant concern is the reduction of soil pH, making the area more acidic over time. Most turfgrass varieties thrive in a near-neutral pH range, and a significant drop can negatively affect their overall health and ability to absorb nutrients. This change in soil chemistry can also harm the beneficial microbial communities that are responsible for breaking down organic matter and cycling nutrients. Soil acidification can make essential elements like phosphorus and magnesium less available to plant roots, even if they are present in the soil.