LECA is an acronym that stands for lightweight expanded clay aggregate. It is made up of little balls of clay—a growing medium—and used in place of soil.
you can use LECA instead of soil to grow indoor plants. Unlike soil, LECA is a lot less messy than soil and is naturally neutral, making it a great substrate for indoor plants. These clay pebbles can provide an ideal balance of moisture, food and air for your indoor plants.