What is it?
Pumice is very porous and has a kind of abrasive surface texture. It is produced as a product of volcanic reactions. It absorbs and slowly releases fertilizers and as it drains well, it would be rather difficult if not impossible to over-water. This is another reason why pumice, especially of this size is suitable as a drainage layer; root rot can be avoided. Although roots cannot grow into pumice, just like Leca and stone, roots seem to like pumice and readily ramify in mixes which contain a fair amount of it.
How to use?
This medium size of Pumice is ideal as a bottom layer in deep or larger pots where it is recommended that it be combined with the same particle size akadama.