Soil – The most common and familiar medium for hobbyists, amateurs, and professionals. Not all soils are created equal; there are many different types and mixes. Soil is typically the go-to medium because of its accessibility and low price. Soil is also more forgiving and can be easily managed. When picking a soil or soil mix, it’s important to consider factors such as aeration/texture, pH, fertilizer/amendment content, and infestation (Soils are likely to contain a pest or pathogen). Most potting mixes are pre-mixed with fertilizers and amendments, but will typically still require supplemental fertilization in the later stages of growth. Mixing your own soil is the most efficient way of controlling the amendments and additives, however this may seem and can be daunting and overly time-consuming. New growers often opt to just buying quality commercial potting soil while advanced growers will find the control of creating their own mix beneficial. Some beginners will prefer to use coconut fiber instead of soil for its drainage properties (overwatering is more common with soil than coconut fiber)
Coconut Fiber – Coco-fiber, sometimes called Coco Coir, is made from the husks of coconuts, and can be purchased as pith, fibers, or chips. Coco may be the most forgiving grow media available. It is popular for many reasons, one being the fact that it’s one of the only completely organic mediums available for hydroponic systems. It’s also known and popular for its very efficient and large oxygen and water capacity, which is a good fail-safe for hydroponic related problems. Akin to soil, it acts as a filter for nutrients, which helps prevent nutrient burn. Unlike soil, coco has a sponge-like quality that prevents compaction. Additionally, coco coir’s excellent water retention properties allow for flexibility in your watering schedule. It’s also suggested to amend your coco-mix with root soil and root beneficials, such as Mycorrhizae.
Perlite – Mostly used in amending Soil or Coco, perlite is blended in mixes to provide media aeration while not hindering or greatly affecting water retention. As soil and coco break down, perlite will prevent compaction. It’s very advised to add Perlite to your Soil or Coco mix. Perlite isn’t recommended to use as a standalone media.
Expanded Clay Pebbles – Clay pebbles can be used as a standalone media or as an amendment to coco or soil. Similar to perlite, clay pebbles have low water retention and act as a great media aerator while not heavily affecting moisture levels. While there are many advantages to using a medium with low water holding capacity, under-watering can severely affect and/or kill your crop.
Rockwool – Rockwool is another popular medium used in both soil and hydroponic systems. Made from basalt rock which is melted and spun into fibers. The primary advantage of rockwool is that it has high water retention, which means that your plants are less likely to be affected by under-watering or a broken pump. It’s also important to mention that the dust and fibers from rockwool can be hazardous, and that the material’s high pH level may require you to pay special attention to the pH level of your nutrient solution and waterings.
Once you’ve decided upon a grow media you like, continue to do research to help conclude your decision. The growing mediums discussed above may offer several additional properties, benefits or disadvantages that may not have been listed. Talk to your local Garden or Hydro shop for more information, and take a Horticulture course at Oaksterdam University to learn further information and about other mediums and more about both indoor & outdoor soil sciences and preparation!