The appearance of grass and weeds in the cracks of sidewalks and driveways is a common issue for property owners. Narrow gaps accumulate dirt, dust, and organic debris, providing a suitable medium for seeds to settle and germinate. Coupled with trapped moisture and sunlight, these cracks function as miniature planters where resilient vegetation thrives. Addressing this requires a multi-pronged approach, moving from immediate removal to long-term prevention.
Mechanical Removal Techniques
The simplest method for removing vegetation involves physical force and specialized tools. Hand-pulling is effective, especially when the soil is damp, which helps ensure the entire root system is extracted. Specialized crack scrapers, wire brushes, and utility knives are designed with thin, angled blades that fit into the narrow crevices to cut and pull out the weeds.
For larger areas, a flat-bladed shovel or a dedicated sidewalk weeder can quickly scrape out the visible growth and debris. Another non-chemical option is the use of a propane weed torch, which uses intense heat to instantly destroy the plant’s cellular structure. When using a weed burner, ensure the area is clear of dry, flammable materials and keep a fire extinguisher nearby.
DIY and Natural Weed Killers
Household ingredients offer effective, non-toxic alternatives to chemical herbicides for spot treatment. Pouring boiling water directly onto the weeds provides thermal shock, rapidly scalding the foliage and stems. This method is most effective for young, small weeds and works well because the heat is contained, but it may require repeated applications for deep-rooted perennial plants.
High-concentration white vinegar, which contains acetic acid, acts as a contact herbicide by dehydrating the plant cells. Standard household vinegar (typically 5% acetic acid) can be boosted by mixing one gallon with one cup of salt and a tablespoon of liquid dish soap. The dish soap acts as a surfactant, helping the solution adhere to the waxy leaf surface.
Salt (sodium chloride) is a desiccant that draws moisture out of the plant, but caution is advised. While effective for killing growth, salt can damage concrete surfaces over time and sterilize the surrounding soil. Therefore, salt solutions should be confined strictly to the cracks and kept away from desirable lawn or garden plants.
Choosing Commercial Herbicides
When persistent or deep-rooted weeds require a stronger solution, commercial herbicides provide reliable results. These products fall into two categories based on their mode of action: contact and systemic. Contact herbicides kill only the parts of the plant they touch, providing a fast knockdown, but they are less effective against perennials with extensive root systems.
Systemic (translocated) herbicides are absorbed by the foliage and move through the plant’s vascular system to kill the entire structure, including the roots. Non-selective systemic products, such as those containing glyphosate, are recommended for paved areas because they eliminate all vegetation they contact. Always read the product label to ensure it is rated for use on paved surfaces and to understand the required personal protective equipment (PPE).
Apply herbicides on a calm day to prevent drift onto non-target plants and follow all local regulations, especially concerning runoff into storm drains or waterways. Systemic herbicides take longer to show results, often a few days, but they are more effective for long-term control of established grass and weeds.
Long Term Prevention
Removing existing growth is only a temporary measure without addressing the conditions that allow the grass to thrive. The most effective long-term strategy involves sealing the cracks to eliminate the space where seeds and debris accumulate. First, the cracks must be thoroughly cleaned of all soil and organic matter, often using a screwdriver and a shop vacuum or hose.
Once clean and dry, the crack can be prepared for sealing. For wider joints, a foam backer rod is pressed into the gap to provide a base for the sealant, ensuring correct depth. A flexible, self-leveling concrete or masonry sealant is then applied over the backer rod to create a waterproof, permanent barrier.
For smaller cracks or joints in paver stones, polymeric sand can be swept in and misted with water to harden, locking the material in place. Routine maintenance, such as regular sweeping to remove dirt and debris, will minimize the material available for new seeds to germinate. Sealing the crack removes the weed’s habitat, making future growth virtually impossible.