GROW YOUR MEDICINE Soils and Mediums

There are many options to grow with, and many different types of marijuana growing soils and products of which one is best.  One of the fun things about growing cannabis is experimenting with different techniques and finding the one you feel most comfortable with.


Soil is composed of clay, sand, rock and organics. Organics are decomposed animal and plant matter that provide the soil with nutrient content.  The rocks and sand provide drainage that helps the roots grow while the clay helps with moisture.  Soil is often full of microorganisms that are breaking down the organics contained within it by feeding on them.  Soil works very well in the ground but can heavy in containers because it can clump.  The use of other ingredients with soil can help lighten it and help water distribute evenly throughout it.

Some of the highest reviewed potting soils include:

  • Happy Frog Potting Soil
  • Roots Organic Potting Soil
  • Vital Earth’s Organic Potting Soil


Perlite is a porous white substance that is used to stabilize water holding in plant mixes.  It is very light and actually floats in water.  Perlite is usually used for cloning and mixing with other grow mediums but in some cases is used as the primary medium.

The Whittemore Company has been supplying perlite products since 1919 and we recommend them for all your perlite needs.

Warning! When handling perlite, because of the dust it gives off, the use of a respirator device or facemask is recommended so as not to damage your lungs.


Vermiculite, crushed volcanic rock, known as “puffed mica”, is medium that provides great drainage when mixed with other grow mediums. It holds water as well as a sponge and because of this, it is often mixed with other ingredients to help with air and water retention.

Vermiculite is very lightweight.  Vermiculite is not often used as a stand-alone medium.
We have had good results with Espoma Organic Vermiculite from
Warning! Dry vermiculate is harmful to breath. Before using it, wet it down so the dust doesn’t get in your lungs.


Rockwool is spun rock that comes in multiple sizes of cube.  The smaller cubes are often used for seedlings or clones, and are great at draining moisture.  The larger blocks are regularly used in hydroponic systems such as ebb and flow trays.  To make sure there are no air bubbles present, it is recommended to submerge Rockwool in water for 8 hours prior to use.

Rockwool works well with Marijuana roots because it has porosity that helps hold air and water.  It also is the right density so roots can easily grow and move throughout Rockwool.  Rockwool is sterile, meaning it has no nutrients.

When purchasing rockwool we always recommend using Grodan’s products.
Warning! When using rock wool it is recommended to use a facemask when handling it.
Rockwool gives off noxious fibers and should be wetted before use to avoid them.

Hydroton, Coconut Fiber and More at: Cannabis Training University


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