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Growing Mediums for Cannabis

Growing Mediums for Cannabis

Growing Mediums for Cannabis are more diverse than ever. Let's unearth the nitty gritty about soil, soilless and hydroponic substrates.

Any good grower worth his or her salt will tell you that "you are not feeding the plant; you are feeding its roots". Roots are a vital component of success yet are easily overlooked and just as easily over cooked. A good growing medium will provide roots with a perfect environment for oxygen, water and nutrient uptake. The many options available for every sort of grower are amazing but can be a little bit confusing. Here's what you need to know about growing mediums for cannabis.

Potting soil is not pot soil

Off the shelf potting soil from your local nursery or store is the quickest way to fail before even starting. These products, while excellent, are not designed for cannabis seeds or clones. Young weed plants do not like nutrient dense growing medium. Commercial potting mixes are often referred to as being "too hot” and could lead to very yellow plants that barely survive more than thrive. Don't be afraid to spend a little or lot more on a cannabis orientated medium. Sure, it may cost more than the traditional garden products, but it is still pound for pound one of the most affordable essentials of your grow.

The science of growing mediums

An optimum medium needs to not only meet your plants' needs. It also needs to meet your needs. Having to water and feed daily may not be ideal. Dealing with too much water could also be an issue as plants may drown. So, it is certainly worth understanding the basic principles of any soil or soilless medium. Roots require access to oxygen, water and nutrients in order to feed the plant. Too much or too little of either will deliver poor to no results.
Growing mediums are what hold these essential elements for roots to feed on. They can also regulate these elements for out of this world performance. Thereby allowing you to fully customize the experience for both your plants and you.

Soil, soilless and hydroponic growing mediums for cannabis

Soil based mediums are just that, a soil or mostly soil mix of organic matter used to grow plants in. Just about every commercial or informal "soil" that comes in a bag is however a blend of several substrates and additives, with little to no actual soil content. These soilless mixes have gone a long way to blur the line between traditionally hydroponic and organic growing mediums.
Many growers therefore no longer stick to just purely one form of medium. Choosing to rather use blends that offer a harmony of pre-mixed options designed specifically for cannabis. Good grow stores should carry both a good pre-mix range, as well as loose components.

Understanding the ingredients

Coco Coir: The fibre from coconuts is process into a substrate that is excellent in retaining water and oxygen. It is therefore a very popular choice among synthetic and organic growers. Care should be taken not to overwater as coco coir is easily saturated. Popular mixes include a portion of perlite for more balanced performance.


Vermiculite:  This spongy and reflective looking substrate is made by super heating silica. The silica expands into an organic foam like texture. Vermiculite can be successfully used on its own or with other components in just about any system. This substrate is an excellent all-rounder for organics or synthetics.


Peat Moss: Harvested from huge bogs, peat moss holds significantly more water than coir. We therefore therefore highly recommended to add either perlite or expanded clay for better oxygen uptake. Peat moss can be used to add moisture retention to mediums that dry out too quickly.

Hydroton/Expanded Clay: These round pebbles have a brick texture that offers massive amounts of internal surface area for water, nutrients and air. Expanded clay is one of the most popular substrates in hydroponic systems for good reason. It is very forgiving and performs exceptionally well when mixed into a peat or coir based medium.

Perlite: The process of super heating obsidian sand causes it to popcorn into white porous granules. Like expanded clay it offers massive amounts of internal surface area for water, nutrients and air. Perlite is another substrate that performs excellently in hydroponic systems and as an additive to organic growing mediums.

Rockwool: Made by heating and spinning basalt rock in a candy floss like process. Rock wool is a turnkey medium best suited to synthetic growers. It is a bit tougher to compost and is not easily reusable. Whereas all of the above substrates can be simply recycled into your garden, rockwool may take more effort or creativity to get more than one use out of it.

Living Soil: Any good soil or soil-based medium is full of life thriving on organic nutrients. Living soil includes micro-organisms that predigest nutrients and provide them to the plant's roots. This makes these medium simpler in terms of feeding nutrients but does require a more hands on approach than most of the above options.

Avoid big claims and pesky pests

It may surprise you to learn that some potting soils prey on new growers. Boastful branding does not make for a good product. Only purchase premium substrates and growing mediums with a proven track record from reliable sources. As you could quickly be separated from your money and end up with something that couldn't even grow a magic bean.
Worst yet... it could introduce a whole new world of fungus gnats, aphids or spider mites to your precious garden or grow groom.
Need a little help making up your mind about a growing medium for cannabis, please contact our grow pros for some top shelf advice.

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