Your marijuana plant will thrive as long as the roots have room to grow and have consistent access to fresh water, oxygen, and the proper nutrients. There are a variety of ways to satisfy all these needs of a weed plant while growing.
A growth medium or grow medium is whatever it is that you're growing your cannabis in, whether that substance is soil, perlite, coco coir, rockwool, water, etc.
Growth Mediums for Marijuana
Soil or compost is one of the most popular growing mediums for marijuana plants becauseit is natural, easy to use, and available everywhere. If you decide to use soil, try using a sterilized, loose, non- peat based potting compost. I recommend mixing your soil 50/50 with a soil conditioner like perlite which will provide drainage and keep higher amounts of air/oxygen in the soil.
Soilless mediums such as rockwool, perlite, vermiculite, and coco coir also all make great marijuana growing mediums. My preferred method for beginning growers is to start out their plants with a mixture of half perlite and half coco coir and then water their plants by hand. I have written a detailed tutorial on how to grow marijuana with perlite and coco coir. Soilless mediums are great because you can treat your grow almost the same as soil only you just feed them all their nutrients in the water (hydroponically). Because your plants are getting the nutrients delivered directly to their roots, you will often get quicker growth and higher yields when growing hydroponically. Another advantage of soil-less mediums is that you are less likely to have problems with mold or bugs.
Other hydroponics have you grow your cannabis directly in water or even in air. The style of hydroponics which seems to get the highest yields is a method known as bubbleponics or a top-fed Deep Water Culture (DWC) system. I have a tutorial which will show you how to grow your marijuana plants using the bubbleponics method.
Similar to vermiculite and perlite, clay can be heated and expanded. However, with clay, the medium becomes much harder after heating. Still, the clay aggregate is porous enough to give it some decent water-holding ability, though not enough for systems using a single daily watering. Rather, this medium is better suited for continuous-flow or multiple-watering hydroponic systems. Inert and sterile with neutral pH, HEC offers little to no buffering properties, but it is highly stable and capable of holding seedling or clone plugs in active hydro systems. HEC can also be used as a bottom layer for drainage in plant containers or as a mixed-in additive for soilless mixtures.
Often referred to simply as “coco,” coconut fiber can come in a variety of forms including shredded fibers, small cubes or a finer, more granular medium. Coco is often mixed into soilless mixtures with peat and vermiculite, but it can also be used as a stand-alone medium for potted plants. Derived from coconut husks, coco is sterile and has good water-retention and buffering properties.
Correct medium choices help genetics reach their potential as seen with this pink Jah Goo.
Very similar to peat moss, sphagnum is a moss composed of dehydrated acid-bog plants. Being perhaps the most desired moss for agricultural use, it is expensive to produce and as such, it is often used in soilless mixtures alongside peat moss. Sphagnum has very high water-absorbing properties and can absorb 10 to 20 times its dry weight in moisture. Sphagnum moss has a pH between 3.5 and 4.0. Much like peat, sphagnum offers excellent buffering qualities for the root structure, helping to prevent nutrient burn and making it very forgiving for beginner growers.
Long-time reader, first-time grower here! As my wife and I begin our journey in growing, I wanted to get your take on the abundance of indoor grow mediums currently available on the market. As first time growers, we are leaning towards using soil and hand-watering the plants, as I have seen you recommend this approach for beginners several times over the years. However, we are open to doing a hydro system if the medium and system are easy enough to handle. Any advice is much appreciated!
That being said, let’s take a quick look at a few of the most popular mediums for indoor gardens:
Hardened expanded clay (HEC) being used in a flood-and-drain hydro table.
Thanks for writing in Carlos & Melinda—and congratulations on starting your first grow! That is music to our ears here at High Times!