A wildly popular and simple hydroponic growing medium, expanded clay is lightweight and nearly inert, meaning it’€™s pH neutral and releases virtually no minerals into the nutrient stream. Due to its incredible ability to hold oxygen and nutrients, expanded clay is an ideal growing medium for rooted clones and mother plants. Next to soil, it’s the most versatile growing medium.

As an added bonus, the pellets can be reused and are considered an ecologically sustainable growing medium.

Made by many manufacturers, expanded clay is sold under the brand names Hydroton, LECA, GroRox, Geolite and others. The pebbles are best used in net pots, drip irrigation systems, water culture systems and ebb and flow systems.

When transplanting rooted clones into expanded clay, above all, be gentle. And if using new pebbles, thoroughly rinse them with water until the runoff is clear; if reusing them, clean them with a sterilizing solution, rinse and remove any dead roots and dust.

The healthy roots should be at least one inch long when transplanted and placed with care into their new homes.


  • When cleaning, either use a bleach-water solution or hydrogen peroxide-water solution.
  • Some growers mix expanded clay with other grow mediums to increase the oxygen retention.