Block paving is a popular home option for walkways and patios. But over time, even well-laid paving can fall prey to weed growth. Poorly laid or degrading substrate may allow weeds to grow up from the soil or the weed's seed may land and germinate in dirt nestled in the joints between the pavers. Whatever the cause, weed growth is potentially damaging. Over time, the weeds' foliage and roots can actually crack and damage the pavers. Luckily, these weeds are relatively easy to kill using a number of solutions.
Spray the weeds with an herbicide. A glyphosate-based broad spectrum herbicide will kill any weeds (or plants) it comes into contact with. Follow the manufacturer's instructions for application rates and amounts. For a more natural option, pour lemon juice or boiling water onto the weeds.
Monitor the paving stones for regrowth over the next two weeks. Persistent perennial weeds growing up from the soil between pavers may require one or more treatments.
Pull up the weeds once they're dead.
Control weed seed lying dormant in the soil between pavers with corn gluten meal. Corn gluten meal is available at health stores and home and garden centres (labelled as a weed killer). Sprinkle it in the joints in early spring as soon as temperatures begin to warm, three to five weeks before the weeds sprout. If it rains within 72 hours after applying the corn gluten meal, reapply the layer.
Brush the paving stones with a long-handle brush to remove any surface debris that weed seeds may be rooting in. Weekly brushing will take care of most surface weed invasions. If the weeds are growing up from the soil beneath the pavers, repeated treatments may keep them at bay. For a more permanent solution, have the paving stones removed by a professional and replaced over a black polythene plastic barrier over the soil. The barrier will control weed growth for up to five years.