What are LECA balls, and should I use them for growing my indoor plants? I have been seeing them for sale at garden centers.
LECA stands for ‘lightweight expanded clay aggregate,’ and is made from clay, brick dust, and waste from the processing of albite (a sodium-rich mineral derived from feldspar). The primary use of the clay balls is as a substrate in hydroponic growing. A similar product is sold under the brand name Hydroton. From the point of view of hydroponics, LECA may be beneficial because the spaces between the clay balls offer more airflow and ease of root development, but the LECA balls have “limited water holding capacity (only a problem if you forget to water or let the water level drop).” Their absorption rate varies based on the make-up of the aggregate; the more pulverized brick and albite, the less they absorb.
Houseplant enthusiasts may mistakenly assume that using LECA balls will free them from being attentive to watering and drainage concerns. Some promoters of the clay balls suggest that you can soak them and grow your indoor plants in a container without drainage holes because the balls somehow magically provide the roots with just the right amount of moisture. It may be a stylish (if expensive) look, but it is still best to grow your indoor plants in the appropriate potting soil for their needs, and in containers with drainage. Definitely do not mix clay balls with potting soil, and do not use them in the bottom of containers. The myth of improving drainage by putting various items in the bottom of a pot (whether an indoor or outdoor container) has been debunked. Don’t create a perched water table by putting anything—clay balls, broken pottery, rocks, etc.—in the bottom of the pot. When we do this, “water percolates through the soil and, upon encountering the different layer, the water moves sideways, creating a saturated zone. Water in this saturated zone gets ‘hung up’ [or ‘perched’] on the layer that is different.”