Grass and weeds in the narrow gaps of sidewalks and driveways is a common maintenance issue. These cracks provide a protected environment where wind-blown debris and soil accumulate, creating a perfect seedbed for unwanted vegetation. Addressing this persistent problem requires quick and effective techniques that target the plant while minimizing damage to the surrounding pavement. The following methods offer various solutions, ranging from immediate physical removal to long-term chemical and structural fixes.
Physical and Thermal Removal Techniques
Physical removal offers an immediate, non-chemical solution. Specialized tools, such as wire brushes, crack scrapers, or even a sturdy flathead screwdriver, can be used to scrape out the plant material and the soil it is rooted in. This manual process is most effective when the soil is damp, as it allows for the removal of more of the root system, which helps to slow regrowth.
Applying intense heat destroys the plant’s cellular structure. Pouring boiling water directly into the crack causes the plant tissue to rupture almost instantly, acting as a contact killer. For larger areas, a propane-fueled weed torch can be used to scorch the foliage; however, this requires extreme caution and should only be performed in dry conditions away from flammable materials. Both thermal methods primarily kill the visible portion of the plant, meaning deep-rooted perennial grasses may regrow and require repeat applications within a few weeks.
Household Ingredient Solutions
Common household products can be repurposed to create effective, non-commercial weed control solutions. The active ingredient in vinegar, acetic acid, works as a non-selective, contact herbicide by drawing moisture from the plant and causing rapid desiccation. Standard household white vinegar typically contains about 5% acetic acid, which is strong enough to kill young, tender grass but is less effective against mature plants.
For tougher weeds, a cleaning or horticultural vinegar with a concentration of 10% to 30% acetic acid is significantly more potent. To enhance the vinegar’s effectiveness, a small amount of liquid dish soap can be added to the mixture to act as a surfactant, helping the solution stick to the waxy surface of the grass blades. When using any vinegar solution, it is important to apply it on a warm, sunny day when the sun’s heat can accelerate the dehydration process.
Adding salt, such as table or rock salt, to a vinegar mixture can increase the killing power by disrupting the plant’s internal water balance. However, this practice should be approached with caution, as sodium does not break down readily and can sterilize the soil, preventing any future growth in the area. Excessive salt application may also contribute to the degradation of the concrete or pavement over time. Therefore, salt is best reserved for use in contained areas where soil contamination is not a concern.
Commercial Herbicide Use
For a more lasting solution, manufactured chemical herbicides provide targeted control over unwanted vegetation. These products are broadly categorized into two types based on their mode of action: contact and systemic. Contact herbicides, like the thermal and vinegar methods, kill only the plant parts they directly touch, resulting in a quick visual effect, often within hours or days.
Systemic herbicides are absorbed by the plant’s foliage and translocated through its vascular system down to the root structure. This mechanism is especially useful for established perennial grasses, ensuring the entire plant, including the underground root crown, is eliminated. Non-selective formulas are the most appropriate for sidewalk cracks, as they kill all vegetation they encounter without discrimination.
When applying any commercial product, follow all safety precautions, including wearing protective gloves and eyewear. The product should be applied directly into the crack to thoroughly coat the grass and minimize runoff onto surrounding desirable turf or landscaping. For best results, use a product with a built-in applicator wand or a dedicated sprayer to ensure precise delivery of the chemical agent.
Preventing Future Growth
Once the grass is killed and removed, implementing preventative measures is the most effective way to address the recurring nature of the problem. Grass and weeds take root in the organic matter and loose soil that collects in the cracks. Routine sweeping with a stiff broom helps to remove this debris, starving any newly germinated seeds of a suitable growing medium.
The most permanent solution involves physically sealing the crack to block the entry of seeds, soil, and sunlight. For narrow gaps, a flexible, self-leveling concrete caulk or sealant designed for pavement joints is recommended. Before application, the crack must be thoroughly cleaned and often lined with a foam backer rod to provide a stable foundation for the sealant.
In paved areas like walkways with pavers, replacing the existing joint sand with polymeric sand can significantly inhibit growth. This specialized sand contains additives that solidify when activated by water, creating a firm, weed-resistant barrier between the stones.