How to Keep the Weeds out of My Lava Rocks

Remove the existing lava rocks from your flower bed or landscaped area. Place a large sheet of black plastic near the rocked area. Shovel the lava rocks into a pile on top of the plastic.

Dig up any exposed weeds, removing the entire root system. Dig down a couple of inches to expose any new weed growth or segments of live weed roots. Work these out of the soil with a sturdy hand rake. Smooth the soil to form an even surface.

Cut a thick piece of landscape fabric. Use a fabric that carries a weed-proof guarantee of at least 10 years. This type of weed-blocking fabric is generally more expensive than common black plastic, but it will last longer and require less maintenance. Cut the fabric long enough to tuck under the edging around this area of landscaping. Cut holes in the landscape fabric to allow space for any existing plants. Cut the plant holes in the shape of an X, folding under the cut edges to create a small square around the base of each plant. Hold the fabric in place with landscape fabric staples around the edges of the cut holes.

Shovel the lava rocks from the pile onto the landscape fabric. Spread the rocks out evenly, allowing about 2 inches of open space around the base of each existing plant. Add additional lava rocks to create a thickness of rock mulch that measures about 3 inches deep. This thick layer will help block out sunlight and discourage future weed growth.

Hand-pull any weeds as soon as you notice them growing in your lava rock area. The most likely area for weeds to emerge is directly around the base of each plant. Water the soil about 12 hours prior to weeding, then pull the weeds directly upward to avoid breaking off the roots or disturbing the soil around the adjacent plants.