Lava rock is a more permanent mulch solution than organic options such as wood chips. The rocks are heavy, so they're less likely to wash away during rain or blow away in the wind. Because they stay in place, the lava rocks tend to collect leaves and dust in the cracks and crevices between the rocks. This can create an ideal breeding ground for weeds, so clean your lava rock beds periodically to keep your flower beds healthy and attractive.
Pull weeds that are growing between lava rocks. These might have rooted in dirt between the rocks or from the ground below the rocks. Scoot the rocks over with a trowel if necessary to make sure you pull the weed out from the roots rather than removing only the stalk. Replace the rocks.
Blow the leaves off the flower bed with a leaf blower. Set the blower on high if you don't have fragile flowering plants in the bed. A high setting can damage young or newly flowering plants, so use a lower setting if necessary. The benefit of a higher setting is that it can blow debris out of deep crevices between the rocks.
Spray the rocks with water from your garden hose to wash away dirt and dust. Spray toward the drainage angle. For example, if your flower bed slopes down from your house toward the road, stand against your house and point the hose across the rocks toward the road to help the dirt drain along with the water. A gentle shower helps remove surface dust, but use a more powerful, focused stream of water to dig deeper between the rocks. Don't shoot your plants with a strong stream of water to prevent damage to the leaves.
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Things You Will Need
- Gardening gloves
- Leaf blower
- Garden hose
- Most lava rock applications have a layer of weed-control fabric underneath. If you pull weeds that are rooted in the ground as opposed to rooted between rocks, push aside some rocks in that area to check the integrity of the fabric. It tends to break down over time, especially at seams, and it might require replacing.
- If you move lava rocks while cleaning them, make sure to keep them away from the stems of plants when you replace the rocks. The dark-colored rock tends to trap heat in the soil and can cause the plants to get too hot in the summer.