Perlite

Perlite has been known for years as soil additive and growing medium, used to increase aeration and soil drainage. Perlite belongs to mined materials, originating from volcanic glass. This natural material breaks into multiple tiny bubbles, when heated rapidly above 1600 deg. F.

Being one of the best hydroponic growing media, perlite is usually used by itself or as a component in mixtures with other mediums. Often it is vermiculite, which is mixed with perlite in equal proportion. Besides, perlite is often used as the major ingredient of soilless mixtures. Perlite is characterized with good wicking ability and thus it is commonly used in wick-type hydroponic systems. Finally, perlite is a relatively inexpensive growing medium.

The biggest weak point of perlite is that this material cannot hold water long enough. It means that perlite growing medium dries out quickly and requires more frequent watering. Besides, perlite dust can be harmful for human health, and it is recommended to wear a protective mask while working with it.

Vermiculite

Being another mined material, vermiculite resembles mica rock in its natural state. Under the influence of high temperature, this material breaks down into small parts just like perlite.

It is a common practice to use vermiculite in conjunction with perlite in hydroponics systems, since these two ingredients complement each other. Vermiculite is capable of retaining high volumes of moisture (up to 200% - 300% of its own weight); and since perlite cannot hold water that well, it is easy to balance your growing medium, so that it holds water and nutrients, while still supplying enough oxygen to plants roots. Usually, a 50/50 mixture of vermiculite and perlite is used for hydroponic systems of drip type, as well as for ebb and flow systems. Similarly to perlite, vermiculite is also an inexpensive growing material.

The major drawback is that vermiculite retains too much water. This material should not be used by itself as the only component of growing medium