Eliminating Weeds Between Pavers Without Damaging Stone

Two years after patio installation, weeds have invaded the paver joints because the recommended joint-locking sand wasn't applied. The homeowner is hand-pulling weeds but fears herbicides like Roundup might discolor the pavers.

Effective Solutions

Pre-Emergent Granules: Prevent Future Weeds

A pre-emergent herbicide in granular form (available at home improvement stores for approximately $10/pound) creates a barrier that prevents new weed seeds from germinating. The sandy formulation sweeps easily into paver joints. It won't harm tree roots and works well on driveways and patios alike. This is a proactive solution—it stops new weeds but doesn't eliminate established ones.

Roundup Concerns: Largely Unfounded

Glyphosate (Roundup) rarely discolors concrete or natural stone pavers. For peace of mind, test on an inconspicuous corner first. Apply carefully to weed foliage only, avoiding overspray on the pavers. The herbicide translocates to the roots, killing the entire plant. Any wet residue dries quickly and breaks down with UV exposure.

Recommended Approach

1. Spot-treat existing weeds with glyphosate on a calm, dry day
2. Wait 7-10 days for complete kill
3. Remove dead weed debris
4. Apply polymeric sand or joint-locking sand to stabilize joints
5. Follow with pre-emergent granules twice yearly (spring and fall)

This combination addresses current weeds, stabilizes the patio surface, and prevents future invasions with minimal chemical exposure.