Growing Media
Growing media in hydroponics is the term used for the material provided in which plants can grow and in which plant roots can derive nourishment from the nutrient solution that usually permeates the medium used.
It is often referred to as ‘substrate’, although strictly speaking, these are slightly different things.
There are several different types of growing media. Growers will select which one to use based on how well it performs with a particular plant species and the nature of the medium’s attributes, especially its ability to absorb and retain water and nutrient solution. Some growers will develop a liking for a particular medium over time. Others will experiment early to see which media performs best for their crop and circumstances.
Coco coir consists of ground coconut husks from tropical parts of the world. The husk is the growing medium for coconuts to germinate and produce new trees.
Clay Pebbles consist of expanded clay formed into porous pellets. They are pH neutral and provide an excellent water-to-air ratio.
Perlite is a soil-free growing medium that provides additional aeration to soil mixes. It has excellent oxygen retention and is exceptionally porous.
Many growers use a hybrid combination of two or more growing media in their pots. There is no hard and fast rule for choosing these; it often just boils down to personal preference and what people like.
Sometimes a nutrient manufacturer or a hydroponics expert will recommend using one medium over another or perhaps point out a combination of two which work exceptionally well together when used in a specific growing method.
Popular growing media include coco (also known as coco coir), clay pebbles, Rockwool and perlite. Some combinations work exceptionally well together because the attributes of two or more complement each other in terms of the ease of plant uptake of the nutrients they receive daily. So the general rule is to follow any specific instructions given for the type of plants you’re working with or the advice given by the nutrient manufacturer.
