What Is Semi Hydroponics?

by Lettuce Be | Last Updated:

Using a technique called semi hydroponics, ‘semi hydro,’ or hydroculture, plants are grown without soil, bark, or peat moss. A semi hydroponic system uses an inorganic, inert, and solid growing medium instead of true hydroponics. The roots of the plant are suspended in a liquid solution as the growing medium. The main material used (LECA, or clay aggregate) is a highly absorbent, lightweight, extremely porous, and low-density material.

As opposed to true hydroponics, semi – hydroponics utilize capillary action rather than pumps. The wicking action of the media allows nutrients and water to be pulled from a reservoir into the roots, providing them with a constant supply of nutrients and water.

LECA: What is it?

LECA (Lightweight Expanded Clay Aggregate), also known as expanded clay balls or expanded clay, is a semi-hydroponic/hydroculture growing medium crushed to a fine aggregate. A rotary kiln-based process is used to heat clay to extremely high temperatures to produce clay pebbles. Expansion of the clay by the gases produces thousands of tiny air pockets or pores, which look like honeycombs. These aggregates can vary in size and have hard outer shells and porous inner structures that make them dense and strong.

Features of LECA that can be utilized in semi-hydroponic systems

LECA is an ideal semi-hydronic growing medium because of the properties listed above. Using LECA’s capillary/wicking ability will continuously supply clean water and nutrients to the roots. At the same time, its porous structure will maintain an airy and oxygen-rich environment necessary for healthy root development. Moreover, because LECA is strong and made of inorganic materials, you can reuse it endlessly without losing its strength or becoming compacted.

Basic Semi Hydroponic Setup

You can use various semi-hydroponic set-ups, but the simplest and most basic is what I like to refer to as the ‘inner/outer pot’ method. As an alternative, the plant is grown in a deep saucer with no drain holes or in a shallow pot with drainage holes at the bottom. Essentially, the outer pot functions as a nutrient reservoir (plain water diluted with hydroponic nutrients).

The roots are supplied with nutrients and water through the drainage holes and the LECA that runs through them. Plant roots should be planted about 1/3 of the height of the waterline above the nutrient reservoir when full. You can run water through the inner pot and out of the drainage holes periodically to flush out salt and plant waste; then, you can top up fresh nutrient solution in the reservoir.

Basic Componentes You’ll Need