Lava rock

Source: Bruce McKay

Lava rock

Lava rock is very porous stone that can be used as a substrate in hydroponics

It consists of basalt which is, generally, chemically inert.

Sometimes lava rock contains trace elements of metals that disturb the balance and pH of the nutrient solution.

It must be rinsed thoroughly before use to remove the dust.


  • very porous, retains water very well
  • very light
  • chemically inert


  • has sharp edges that could damage the roots
  • not always easy to find
  • sometimes chemically treated and unsuitable for hydroponics
  • the shape and size of the stones varies greatly and can make it difficult to fill a pot on a evenly


The price varies greatly, depending on the region. In some parts of the world lava rock is available in abundance at low prices while in other parts it may be difficult to find and quite expensive.


Lava rock is especially suitable for ebb and flow systems.