Expanded clay granules

Source: Lucis

Expanded clay granules

Expanded clay aggregate or clay pellets are obtained by firing the clay in a rotary furnace at 1,200 ° C.

At this temperature, the clay expands and forms spherical beads with a cellular structure inside.

The pellets falling from the oven are between 0-32 mm in diameter. They are then sorted by size, depending on the application for which they will be used.

They are also known as LECA (lightweight expanded clay aggregates) or Hydroton (brand).

The expanded clay pellets are used for:

  • construction (insulation, building material, filling …)
  • water treatment
  • plants
  • hydroponics

There is no production aimed specifically at plant culture. You may as well buy the pellets found in DIY stores for construction use, they are cheaper. In both cases, the pellets need to be rinsed thoroughly before first use.


  • very light (380-700 kg/m³ depending on the size of granules)
  • very good ventilation (430 l/m³ empty space between the pellets)
  • high capacity of water absorption: 18-20% of its own volume without changing volume
  • non-compactable
  • durability
  • rot-resistant
  • excellent sound insulation
  • excellent thermal insulation
  • incombustible


  • chemically active, ion exchange capacity
  • alters the conductivity of the water

Though these factors make the expanded clay balls unsuitable for horticulture and agriculture, they have little influence on the culture of ornamental plants annual or vegetables or fruits on a small scale.

You should in any case:

  1. rinse the pellets abundantly before first use
  2. periodically rinse the pellets after the plants are installed (every 3-6 months)


Expanded clay balls are suitable for:

  • sowing of large seeds (avocado, mango, coconut …)
  • growing houseplants
  • orchid cultivation
  • mixed ornamental plant boxes
  • can be mixed with potting soil for better aeration and water retention
  • can be used as a drainage layer at the bottom of a pot