Lava is a porous material that holds water and air well, but it lacks other important nutrients needed for bonsai growth. For this reason, it should be mixed with other substrates to ensure that the bonsai gets all the nutrients it needs.
Lava can also be used as drainage in the bonsai's pot. Place a layer of lava at the bottom of the pot before adding the soil mix. This will drain excess water and prevent the bonsai roots from rotting. Be careful with trees that are sensitive to drought: Although lava holds water well, it can also dry out quickly. If you have a bonsai that is sensitive to drought, you should water it more often with lava and make sure that the soil mixture is always moist.
Keep in mind that different types of bonsai have different needs when it comes to soil mix. Feel free to ask us for tailor-made advice.