Weeds and grass result from seeds or spores blowing into, and lodging in, the joint sand. This can be minimized by using a Techniseal polymeric sand or by sealing the pavers with a joint stabilizing sealer or mixing a pre-emergent granular weedkiller in the joint sand. If weeds do appear, a spot vegetation killer (such as Round-Up™) can be used and will not damage the pavers.