Passive hydroponics

Since routine maintenance is much simplified, passive hydroponics can reduce the labor required to maintain a large collection of plants.

Semi-Hydroponics (Semi-Hydro or S/H) was the first passive hydroponic technique utilized for orchids, originating in the early 1990s, using Lightweight Expanded Clay Aggregate (LECA) as a medium in solid-bottomed containers, into which one or two, small-diameter holes were placed in the sidewall, setting the depth of the internal reservoir.

The Kratky Method is a specialized passive hydroponic technique which involves plants suspended in net pots above a non-circulating water and nutrient reservoir.

The various hydroponic media available contain more air space than more traditional potting mixes, delivering increased oxygen to the roots.

Many media are available for passive hydroponics, but the most common are expanded clay pellets, coconut husk chips, perlite, vermiculite, diatomite, and rock wool.