Splendid LAVA ROCK AccesoriesMixed lava rocks 15 ozA 15 ounce bag of mixed lava rocks. These lava rocks are all natural and organic. Ideal for pots with no drainage holes you can place the lava rocks at the bottom of the planter so the water can pool without drowning the roots. Lava rocks are porous and will absorb and slowly release excess water back to the plant. Perfect for preventing root rot.