Common Soilless Mix Ingredients for Indoor Cannabis Production

Common Soilless Mix Ingredients for Indoor Cannabis Production

Professor DeBacco

Peat Moss
Peat moss: organic product mined from decomposing plants, most often mosses, in a boggy area.
Commonly sourced from Canada for use in the United States and this does cause some growers select not to use this material despite its benefits.
The characteristics of the peat may vary slightly depending on the species of plant that was growing in that area, but overall very consistent product.

Sphagnum Moss
Sphagnum Moss: several species of moss that inhabit bogs. Not a commonly used material but does maintain moisture and aeration.
Can be used in seed starting mixes because of its antifungal properties.

Bark Products
Bark products: Wood based materials that are ground and/or partially composted.
This is a less expensive alternative to peat moss, and does provide more aeration, but it does dry out quicker.
Can require higher nitrogen fertilizers to the plants.
Common bedding material for pets/animals

Perlite: white, volcanic rock that was crushed and heated which results in the material expanding.
Added to many soilless mixes to help improve drainage and increase aeration.
Perlite is non‐toxic, sterile and odorless.
There are different grades (sizes) to fit a variety of needs.

Styrofoam beads: an inexpensive substitute for perlite that has many of the same properties (improve drainage and aeration)
However, unlike perlite Styrofoam will compact over time and may float to the surface reducing its effectiveness.

Vermiculite: very light, greyish puffy substance that forms when mica chips are heated.
Vermiculite contains some potassium, magnesium, calcium and even some silicate that will slowly become available.
It is used to increase moisture and nutrient retention in mixes.
*Preferred option when growing cannabis

Coarse Sand
Coarse sand: large sand particles (washed and/or horticultural grade) are added to improve drainage and weight to a potting mix.
Use is typical for succulents (ex. Cacti) and not very common with cannabis.
Often the draining rate it too fast and sand does tend to add a lot of weight
In addition, sand can damage recirculating pumps which is another reason it is not commonly used for cannabis production.

Water Retention Crystals
Water retention crystals: small translucent granules that are nontoxic, non‐biodegradable and pH neutral.
These polymers can absorb up to 500 times their weight in water and are added to reduce the frequency needed for watering.
However, these crystal do have a life span of up to 5 years, so if you are reusing media the water retaining properties may change as the polymers degrade.
If adding to an existing potting medium, you should always moisten before using and add in accordance to the manufacturer’s directions.

Used to adjust pH to optimum range. Also a source of Calcium and Magnesium.
May not be fully plant available
Often needs to counter act the natural acidity of the peat moss to create a final substrate with a plant favorable pH.

Biological Additives Ex. Mycorrhizae
Mycorrhizae: is a biological growth enhancer that increases the yield of flower, fruit and vegetable plants by extending the root system to acquire the most of available nutrients in the soil.

Mycorrhizae also improve resistance to root diseases and stresses.

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