The choice of growing media depends on several factors. This blog breaks down these factors and the different types of media used within indoor gardening, to help you select the best media for your grow.
What is Growing Media?
Growing media, also known as growing substrate or growing medium, is a material used to support plant growth in various types of plant cultivation systems. It can come in different forms, such as soil, coco coir, peat moss, perlite, vermiculite, rockwool and more.
Growing media aids numerous vital functions for plant growth, including providing physical support for the plant, retaining moisture and nutrients, providing aeration and drainage, and regulating the pH and EC of the root zone. The choice of growing media depends on several factors, such as the type of plant being grown, the growing system being used, and the growing conditions, for example temperature and humidity.
Factors to Consider When Selecting Growing Media
There are several factors to consider when picking a growing media.
Your Growing System – Different systems are compatible with different types of media.
Water Retention – If you’re growing plants without a constant recirculating nutrient system, you will need a growing medium that can hold onto water and nutrients, while still providing good drainage.
Drainage – Good drainage is critical for plant growth. The growing medium you select must provide enough drainage to prevent water logging and root rot. The media used will govern the frequency and duration of your feeds.
EC and pH Levels – The EC and pH levels of growing medium is important for nutrient uptake by the plants. Some media is pre charged with nutrients, or has naturally occurring nutrients. Read our blog on ‘Why you need to know the EC and pH of Soil’ for more information.
Nutrient Availability – Some growing media contains nutrients that can support plant growth. In contrast, inert media requires a nutrient solution to be added to the water.
Sustainability – Some types growing media is renewable and eco-friendly, whereas others have a one-time usage.
Cost – The cost of media varies widely. Therefore, consider your budget when selecting a media.
Types of Growing Media
There are several different types of growing media, including:
The most common and traditional growing medium, which is composed of mineral particles, organic matter, water and air.
Composed of partially decomposed sphagnum moss, which is high in organic matter and can absorb large amounts of water. Peat can be washed and be almost completely inert but provide a good structure for plants to grow in.
Made from coconut fibre, coco coir is a renewable and environmentally friendly alternative to peat.
A natural mineral that is heated to expand its size, creating a lightweight, porous material that provides good drainage and aeration.
Made from volcanic rock that is melted and spun into fibres. Rockwool provides good drainage and aeration while retaining water and nutrients.
No Growing Media:
In hydroponics it’s possible to grow plants without media. This is known as a ‘medialess’ or ‘water culture’ system.
Expanded clay pebbles:
Expanded clay pebbles are made by heating clay to a high temperature, which causes it to expand and become porous. They are lightweight, pH-neutral, and provide good drainage and aeration.
Mixed media offers the benefits of two types of media. For example, 60-40 offers the water retention of coconut coir with the aeration and drainage of pebbles. Mixed media has been developed to offer the users the best of the two types of media.
Ultimately, the choice of growing medium depends on the specific needs of the plants you are growing and the growing system you are using. Experiment with different growing media to find the one that works best for your needs and growing set up.