Black Lava Rock

Black Lava Rock plays a very important part of your soil mixture. Its porous characteristic allows for air to enter your pot and aerates the root system which is the key to a healthy Bonsai. The porous characteristic also helps with water drainage. Its little holes act as a water filtration system so that your soil mixture is never too wet, which is essential to your soil mix. Lava rock is especially important during the rainy season when it rains multiple times a day for a longer period of time.
 

 -2 quarts Bag

Reference: 8 cups per bag. 

- 20 quarts bag

Covers about 1 cubic foot.