The presence of grass and weeds between paving stones is a common issue that detracts from the appearance of hardscaping and can compromise its structural integrity. As organic material accumulates and moisture collects in the narrow joints, an ideal environment is created for seeds to germinate, causing the pavers to shift over time. Successfully clearing and maintaining these spaces requires a multi-faceted approach, combining immediate removal with long-term preventative measures.
Manual and Mechanical Removal
The most immediate and eco-friendly approach to removing unwanted growth involves physical effort and specialized tools. Hand-pulling is effective for small or young weeds, especially after rain when the soil is moist. Always aim to extract the entire root system to prevent rapid regrowth.
For established growth, a specialized weeding knife, often called a patio knife, is highly effective. This tool features a thin, sharp blade designed to slide into narrow crevices to sever the root just below the surface. A stiff wire brush, particularly one designed for paver joints, can also be used to aggressively scrub out superficial growth and debris. For larger areas, motorized wire brush attachments reduce the physical strain of scrubbing.
Chemical and Natural Solutions
For widespread growth, chemical or natural liquid applications provide a faster path to clearing the area. Non-selective herbicides, such as those containing glyphosate, work systemically by being absorbed through the leaves and transported to the roots. Apply the product when weeds are actively growing and the weather is calm to prevent spray drift onto desirable plants. Avoid watering or rain for a minimum of 48 hours after application to allow the chemical to fully translocate.
Horticultural vinegar offers a natural, contact-based alternative, relying on a high concentration of acetic acid to desiccate plant tissue. A concentrated solution of 10 to 20 percent is required for an effective burn-down on mature weeds, as household vinegar is typically only five percent. The acid rapidly destroys the plant’s cell walls, causing the foliage to wilt within hours. Since this method only kills the parts of the plant it touches, deep-rooted perennial grass often requires multiple applications.
When handling concentrated acetic acid solutions, users should wear appropriate protective gear. Concentrations above 11 percent can cause skin and eye irritation.
Heat-Based Eradication
Applying high temperatures is an effective method for destroying grass and weeds in paver joints. Boiling water is an accessible option that kills plant cells instantly through thermal shock, causing the foliage to collapse. This technique is best used for small weeds or fresh seedlings, as the heat may not penetrate deeply enough to destroy the entire root system of established grass. Pour the water directly onto the base of the plant from a heat-resistant container, avoiding splashback onto skin.
For larger areas, a specialized propane-powered flame weeder can be employed. The principle of flame weeding is to briefly expose the foliage to intense heat, causing the water within the plant cells to expand and rupture. This thermal shock is visible when the leaves turn a dull, wilted green color. Heat-based eradication is primarily a top-kill method, meaning deep-rooted weeds require repeated applications over several weeks to exhaust root reserves and prevent regrowth.
Preventing Future Growth
Once the joints are clear of all organic matter, the long-term strategy is to fill the gaps with a material that inhibits new growth. Polymeric sand is the preferred choice, as it contains a blend of fine sand and polymer binders that harden when activated by water. This creates a flexible, solid joint that resists erosion, prevents weed seeds from taking root, and locks the pavers securely.
Preparation and Application
The application process requires a completely dry surface to prevent premature activation. First, the old joint material must be removed to the full depth of the paver. The polymeric sand is then swept into the joints and compacted with a plate compactor or a hand tamper to ensure maximum density. Clear all residual sand from the paver surface using a leaf blower and a fine-bristle broom, as any polymer left on the stone will cure into an unsightly haze.
Activation and Curing
The final step is activation, which must be done with a gentle mist, not a flood. Apply the water in multiple light passes, allowing time between each pass for the water to soak fully into the joint without washing the sand out. This process ensures the polymer binders are saturated from top to bottom, forming a durable, weed-resistant barrier. The area must remain dry and undisturbed for 24 to 48 hours to allow the sand to cure and harden properly.