Small black lava rock is an excellent mix ammendment. Many times if you get a Dendrobium from Hawaii you will notice that it has been potted in either black or red volcanic rock. This lava rock has good water retention with excellent aeration. Because it is inorganic, it will not break down and orchids that resent repotting can be left in their mix longer. Particle size is about 1/8 to 1/4 inch. Volcanic lava rock is an excellent base for an inorganic rock mix. Many times if you get a Dendrobium from Hawaii you will notice that it has been potted in either black or red volcanic rock. This rock has good water retention with excellent aeration. Because it is inorganic, the mix will not break down and orchids that resent repotting can be left in their mix longer. Volcanic rock is a primary ingredient in our Inorganic Blend.
