A soilless mix is a potting mix used for container-based grows that does not contain any soil like a traditional potting mix.
A soilless mix is comprised of a mixture of substrates and is usually considered sterile because there is an absence of living organisms like the bacteria and fungi (good and bad) often found in soil.
Soilless mixes are considered easy to work with because they are lightweight and don’t come prepackaged with diseases or pests. Soilless mixes also give cannabis growers more control over the end product, starting right from the beginning. Using soilless mixes can prevent seedlings and adult plants from being contaminated by soil-borne pests, diseases, and fungi.
Soilless mixes will often contain a mixture of organic and inorganic materials. Sometimes they are also referred to as a “sterile mix”. Soilless mixes can sometimes refer to soilless grow media, which is anything that can be used to anchor a plant in its grow bed. Rockwool and clay pebbles, for example, are two popular soilless grow mediums for cannabis cultivation.
a soilless mixes there can be anything from bark, coconut coir, perlite, and vermiculite, to a predominant mix of sphagnum peat moss, which is lightweight and inexpensive. Growers often add other substrates to their soilless mixes, like compost. Bark is nice because it improves drainage and air space within the mix, while coconut coir provides good drainage while retaining water, and perlite and vermiculite provide additional water and nutrient retention.
Additionally, some soilless mixes may contain a fertilizer or additional trace elements to boost nutrients.