Categories
BLOG

best soilless mix for cannabis

What’s the Best Growing Medium: Soil, Coco or Hydro?

Table of Contents

  • Soil or Compost
  • Soilless Mix (Especially Coco & Perlite)
  • Hydroponics

Introduction to Cannabis Grow Mediums

When talking about growing marijuana, what is a “grow medium”?

A growing medium or grow medium is what you’re growing your cannabis roots in, whether that substance is soil, perlite, coco coir, Rockwool, vermiculite, water, etc. 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 in proper levels. There are a variety of ways to satisfy all these needs of a cannabis plant while growing, and each has its own pros and cons!

Every Grow Medium Must Help Roots Get What They Need: Water, Oxygen and the right Nutrients

Best Growing Mediums for Marijuana

The three main types of grow mediums for marijuana plants are soil mixes, soilless mixes and hydroponics (water). Let’s do a quick breakdown of each one, along with the pros and cons for marijuana growers!

  • Soil or Compost
  • Soilless Mix (Especially Coco & Perlite)
  • Hydroponics

Soil or Compost

Soil or compost is one of the most popular growing mediums for marijuana plants because it is natural, easy to use, and available everywhere.

Good cannabis soil naturally contains at least some amount of nutrients, which means it will provide the nutrients your plants need for at least the first few weeks of life.

Example of Great Cannabis Soil

If you decide to grow cannabis with soil, try using sterilized, loose, non-peat based potting compost. Often these are listed as an “organic potting mix.” I recommend soil mixes with at least 20-30% of a soil conditioner like perlite (little white rocks in the soil). This will provide drainage and keep higher amounts of air/oxygen in the soil, which causes cannabis plants to grow faster.

Plants in soil grow a little slower than in coco or hydro, but soil-grown buds tend to have a stronger smell/taste. Although using a standard soil potting mix and giving nutrients in the water gets results similar to coco, using amended and composted living soil tends to produce buds with a powerful and complex scent/taste profile.

Example of Amended and Composted Living Soil – Just add water!

With living soil, a colony of microorganisms in the soil creates an ecosystem that mimics the best-of-the-best soil in nature. The nutrients are slowly broken down from organic sources and delivered directly to your plant roots. For some reason, plants grown in this type of root environment tend to produce very strong-smelling buds. One thing that’s really great about living soil is you usually don’t need to use any added nutrients.

The result is strong-scented buds grown only with natural processes and all you have to do is just add water and let the soil do the magic! The biggest downside to living soil is that plants tend to grow a little slower than with other grow mediums, and some people don’t like the smell of the composted soil, especially in the house.

Common Cannabis-Friendly Soil Mixes in the US:

  • Composted and Amended “Hot” Soil (great)
  • Fox Farms Ocean Forest Soil (great)
  • Black Gold All Organic Potting Soil (good)
  • Espoma Organic Potting Mix (okay)

Example of Great Soil – Fox Farm Ocean Forest is rich and light, plus it’s packed with nutrients in the right ratio for growing cannabis!

Soilless Mediums (Coco Coir & Perlite)

Soilless potting mixtures that are composed of inert (non-soil) ingredients like coco coir, perlite, peat moss, Rockwool, and vermiculite can be a great choice for growing marijuana.

When growing in a soilless medium, you can treat your plants almost the same as if growing in soil. The main difference is you feed all their nutrients in the water. As a result of your plants getting nutrients delivered directly to their roots, you will often get quicker growth and higher yields than growing in soil (where the roots have to seek out nutrition).

Another advantage of growing in a soilless mix over soil is that you are less likely to run into problems with overwatering or bugs.

Although there are many different possible soilless ingredients, the most popular potting mixes for cannabis contain significant amounts of coco coir and perlite. This combination seems to work especially well for growing cannabis. As a result of coco’s growing popularity, other types of soilless mixes (especially the peat-based ones) have become far less common in cannabis grow rooms over the years.

Even when it comes to soil mixes, you still often see both coco and perlite in the ingredient list, because they help improve the overall properties of the soil.

In fact, I strongly recommend beginner growers start out their plants in a coco-based soilless potting mixture, and I have written a detailed tutorial on how to grow 4-7 oz. of marijuana using coco coir for first-time growers. I’ve also grown a pound of weed in a 2×4 tent using coco coir and a 315W LEC light!

I have personally found coco/perlite to be the most straightforward and forgiving growing medium for indoor cannabis, and over the years I’ve also seen that coco growers seem to be the least likely to run into problems during their first grow!

Coco coir is how I started growing, and I recommend it to anyone 🙂 Here’s me during my first grow with my coco-grown plants:

Learn how to grow cannabis with coco coir or view the Step-By-Step 250W Coco Tutorial to produce 4-7oz on your first grow with coco using auto-flowering strains. I highly recommend this tutorial for beginner growers looking to get started with their first grow!

Common Cannabis-Friendly Coco Coir Mixes in the US:

  • Mother Earth Coco + Perlite Mix (recommended)
  • Fox Farms Coco Loco (great)
  • Roots Organics Soilless Hydroponic Coco Media (great)
  • Make it yourself with our “Coco Coir Rehydration Tutorial (low cost!)

Hydroponics

When people are talking about hydroponics, they’re usually referring to growing your cannabis with the roots sitting directly in water. The most popular style of hydroponics for cannabis plants is known as Deep Water Culture (a.k.a. DWC), and it has a very popular variant known as “bubbleponics” or a top-fed Deep Water Culture (DWC) system.

DWC is one of the few types of hydroponics that can support larger plants. Other types of hydroponics (for example NFT or Aeroponics) have a difficult time growing plants as big and nutrient-hungry as cannabis.

Example of cannabis roots growing directly in a solution of nutrient water

Two hydroponic cannabis plants in the vegetative stage

Example of flowering DWC cannabis plants. They grow so quickly that they can quickly take over your grow room!

Hydroponics can be really scary, but I’ve seen so many first-time growers get great results with hydroponics. The most important thing to remember is to follow the instructions and always get a root supplement like Hydroguard. I love hydro. After growing for several years, I think it may be my favorite grow style. You get the fastest growth and most control over nutrients of any grow medium!

What exactly is hydroponics and is it good for growing marijuana?

By the end of a hydro grow, you may find yourself with huge masses of roots!

Conclusion: What’s the Best Grow Medium for Growing Cannabis?

  • Soil or Compost – Grow in organic composted living soil for the most complex-smelling buds and a “just add water” growing experience. Or start with a cannabis-friendly soil mix such as the popular Fox Farms Ocean Forest soil mix (FFOF already contains enough nutrients to last the first month of your young plant’s life) and give nutrients in the water as plants get older.
  • Soilless Mix – Although this technically includes any grow mix that doesn’t include soil, with ingredients such as coco coir, perlite, vermiculite, etc., most cannabis growers use a mix that’s primarily made out of coco coir and perlite. All soilless mixes are technically considered hydroponic growing since there’s no soil, but most growers think of them as somewhere in between soil and hydro, and you get a lot of the best parts of both. I highly recommend a coco/perlite mix for your first cannabis grow!
  • Directly in Water / Hydroponics – Get some of the fastest growth possible, especially when combined with HID grow lights such as HPS or LECs. I’ve had many of successful grows using a top-fed DWC system, and I think it may be my favorite style of growing.

About Less Common Types of Hydro: Some people grow with plant roots suspended in misted air (aeroponics), in an assembly line (NFT), or in a tank with fish (aquaponics), but these are better suited to smaller plants, and not commonly used to grow cannabis.

So what’s REALLY the best medium? Alright, I’ll stop dancing around what you’re really here for. I’ll rank the popular mediums for different aspects, then I’ll tell you which one I think is the best overall…

Note: The contenders are Soil, Living Soil (composted), Coco Coir (soilless), Hydro (DWC – roots suspended in water)

  1. Hydro
  2. Coco Coir
  3. Soil
  4. Living Soil

Best Smell/Taste Profile:

  1. Living Soil
  2. Everything Else
  1. Living Soil
  2. Coco Coir
  3. Soil
  4. Hydro
  1. Hydro
  2. Coco Coir
  3. Soil
  4. Living Soil

Least Chance of Bugs/Pests:

  1. Hydro
  2. Coco Coir
  3. Soil
  4. Living Soil

BEST CANNABIS MEDIUM OVERALL:

Believe it or not, the best overall medium – in my opinion – is coco coir!

Allow me to explain…

Check out the rankings above; in this case, the medium with the lowest number ranks the best. If you add it all up, Coco Coir ends up being the winner and it’s clear why. Coco coir isn’t the best at anything, but it’s the second-best at pretty much everything: it grows almost as fast as hydro, it’s easier to use than soil, yields second best to hydro and gets fewer bugs than living soil. Coco coir is kind of a jack-of-all-trades and a master of none.

Another cool thing about coco coir is that it’s renewable, so it’s easier on the environment. Most soils use peat which is a finite resource, and hydro can add nutrient water to the water supply. Properly used coco coir doesn’t have any of these problems so you can feel good about using it. Unfortunately, perlite – which is almost always used with coco coir – isn’t renewable, so in a sense, coco coir isn’t renewable because of its dependence on perlite.

Each growing medium that you can use has different care and watering requirements.

Best of the Best: Grow Medium Roundup

We declared coco coir the winner of this little contest, but all the mediums are the best at one thing. Get the best brand of cannabis grow medium to match your preference and grow style.

Common Cannabis-Friendly Coco Coir Mixes in the US:

  • Mother Earth Coco + Perlite Mix (recommended)
  • Fox Farms Coco Loco (great)
  • Roots Organics Soilless Hydroponic Coco Media (great)
  • Make it yourself with our “Coco Coir Rehydration Tutorial (low cost!)

Common Cannabis-Friendly “Living” Soil Mixes in the US:

  • Composted and Amended Living “Super” Soil by Kind Soil (recommended)
  • Super Soil Grower’s Mix by Coast of Maine (good)

Common Cannabis-Friendly Soil Mixes in the US:

  • Fox Farms Ocean Forest Soil (great)
  • Black Gold All Organic Potting Soil (good)
  • Espoma Organic Potting Mix (okay)

Give Roots Room to Breathe!

When growing cannabis in containers, for example with soil or coco, it’s important to give your plant roots enough room to grow. If they run out of space, it will limit the size of your plant, and often causes nutrient deficiencies and other problems like persistent droopiness. If your roots have circled around the edges of the container, it is rootbound and should be transplanted to a bigger container immediately!

Plants don’t really get “rootbound” in hydroponics because the roots are being constantly bathed in a nutrient water solution that provides both nutrients and oxygen to all parts of the roots. However, if the reservoir is too small your plants will drink all the water before you can replace it!

Your cannabis plants need a grow medium! Hopefully, today’s tutorial will help you pick the perfect one for your needs!

You Might Enjoy the Following Growing Tutorials…

More About Various Grow Mediums

  • Yields
  • Bud Quality
  • THC Levels
  • CBD Levels
  • Smell/Taste
  • Density
  • Bud Color (How to Grow Pink or Purple Buds)
  • Glitter (Make Buds Sparkle with More Trichomes)
  • Bonus: What Determines Yields?

What medium makes the best home for your cannabis plants? Is it soil? Hydro? Coco? We'll tell you all about your options and which is the best all around!

How to Make Your Own Cannabis Planting Mix to Maximize Your Marijuana Harvest

Cannabis roots photo by Purple Caper Seeds

Let’s think about roots for a moment. We don’t see them since they are underground, so we hardly ever pay attention to them and often take them for granted. We rarely consider what roots do.

Roots hold the plant in an upright position by branching out and clinging to the media, forming a strong network attached to the stem that braces it against environmental stresses such as wind and rain.

In addition to holding the plants up, roots supply them with water and dissolved nutrients. In a complex process the plant absorbs water by maintaining a higher level of salts than the surrounding soil. Water moves through pores in the roots to lower the concentration in the plant. The same process is used to move water from the roots to the stem and leaves. The roots’ pores act as selective barriers to nutrients to maintain this equilibrium.

“ In order for roots to thrive they require suitable conditions. They must have access to oxygen, water, and nutrients, and be able to grow into the planting mix. ”

Roots maintain a relationship with other organisms to form a symbiotic community. For instance, some mycorrhizae grow hyphae that enter the roots. Other organisms are free-living or form a shield around the roots. These other organisms supply the roots with dissolved nutrients the plant requires, and the plant roots supply them with food, the sugars produced during photosynthesis.

Outdoors, a well-draining fertile soil high in nutrients may need no additional preparation. This is not usually true in soils that have not been used in productive gardens because naturally growing plants don’t require the same amount of fertility as intensively cultivated crops.

Soil is a complex mixture of clay and other weathered minerals, sand, and digested organic matter, as well as myriad variety of organisms, including plants (roots), insects, and other arthropods, fungi, bacteria, and organisms representing other kingdoms. It is so complex a mix that we cannot create it from scratch. However, we can make planting mixes that provide the roots with a healthful environment that promotes a healthy, vigorous plant.

What are the perfect conditions roots require to thrive?

Marijuana plant in raised bed filled with planting mix.

POROSITY AND STABILITY

Cannabis roots require a media that is loose enough for the roots to grow through and form a network to hold the stem upright. Media that is too loose can injure the roots by allowing them to break free from their bonds. As it is colonized by the community of organisms that earn their livings by digesting the organic matter and by providing nutrients to the roots in return for plant exudates such as sugars and other plant products, the community collectively forms a “glue” that holds the particles together.

DRAINAGE

The media must drain well. Media that becomes compacted or soggy prevents air from getting to the roots since there is not much space between particles. It’s not that the media holds too much water, it’s that it doesn’t hold enough air. Unlike leaves that use carbon dioxide as an ingredient of photosynthesis, roots require oxygen for survival and are injured and die under anaerobic conditions.

When water is added to the top of a well-drained mix or soil it starts to percolate down. The medium’s particles grab the water to the point of saturation before they let the rest continue down. In containers the pressure of the water pushes air in the soil down. When water flows from the container’s bottom holes the air is also drawn down by the venturi effect. As the water flows down it creates a vacuum starting at the top of the container. It pulls air into the container as it flows down.

Outdoors, sandy and loamy soils that contain only small amounts of clay drain well and provide a good place for roots to grow. Clay is composed of tiny, closely connected molecules of mostly aluminum and silica that form dense sheets, so the clay becomes plastic when wet but hardens as it dries. When they’re found in small percentages in sandy or loamy soil they help it to hold water and to maintain a stable texture that resists erosion. When soils contain large quantities of clay they drain slowly and hold so much water that air is forced out.

NUTRIENTS

Planting mixes contain nutrients only if they have been enriched. You can grow in a medium with no nutrient value of its own such as coir, peat moss, or bark, or a mineral media such as vermiculite or perlite. All of these mediums support microbial growth once they are irrigated with a water nutrient solution. However, I think plants do better when the planting mix itself contains nutrients. The mix that we are making is enriched with compost as well as added nutrients so the plants will be getting nutrients both from the soil itself as well as from the nutrient/water solution.

Why you want to make your own planting mix for cannabis plants

The compost process uses both bacterial and fungal decomposition as well as red worms, and sowbugs.

Most commercial mixes are made primarily from one base ingredient, usually peat moss or bark. A few contain coir either as the primary base or as an additional ingredient. Most mixes also contain nutrients that may include plant meals, minerals, and animal products.

“ The reason I prefer to make my own mixes is that I prefer not to grow in mixes that contain peat moss, forest products, or dead animals. ”

Three reasons not to use peat moss in your marijuana planting mix

It loses its structure quickly, and under pressure in large containers it compresses, sometimes creating anaerobic conditions. When a mix goes anaerobic it develops an acrid ammonia odor.

It has a low pH, and even after it is adjusted with lime, its pH gradually sinks so it constantly needs adjustment.

It is un-ecological. Peat bogs are part of the north temperate environment. Despite the public relations propaganda showing how ecological strip mining these bogs is, I just don’t think it’s a sound practice to strip the bogs, use the peat moss for a few months, and then dump it in a landfill.

“ Rather than using potentially harmful ingredients I prefer to use plant ingredients and sterilized manures to provide nutrients. ”

Bark is a by-product of the timber industry. Although trees are not felled for their bark it still has its ecological impact because the sale of the by-product makes forestry more profitable. Bark is more pH neutral and takes longer to decompose, so it maintains its structure longer than peat moss.

Ripened compost is sieved through a half inch screen.

The reason I don’t like animal products such as bone or blood meal, leather meal or tankage, is the bad reputation these products have in relation to diseases such as mad cow disease, pathological E. coli bacteria, and other chronic conditions and diseases. For instance, researchers found that E. coli can be transferred from infected fertilizers and nutrients through plants to humans. Mammal manures are supposed to be composted for six months before being used, but this step is often shortened or skipped, potentially leaving bacteria active. Even chicken manure, previously viewed as very safe, is now regarded with some suspicion since the emergence of bird flu and other fowl diseases.

Learn more about what the dangers are for Microbial Contaminants in Cannabis.

The final reason I prefer my own mix is that frankly I think that I use a higher grade of ingredients than is supplied in most mixes to create one that has customized water – and air – holding capacity.

The Base Ingredients you need to make a planting mix for your marijuana

The Base is: Coir, Perlite, Vermiculite, and Compost

Food waste, garden clippings, and small quantities of used planting mix are the ingredients placed in the compost bin. The bin, which is about a cubic yard, takes about a year to fill, and then it ripens for another year.

Rather than using either peat moss or bark we will use coir as part of the base. Coir is the outer husk of the coconut. It is by far the most ecological soil base because it is a farmed by-product of coconut production that has not been used economically. Until recently it was considered a waste product that accumulated in gigantic piles. Now indoor agriculture has created a use for it.

Coir is pH neutral and holds its structure for a long time. It comes as large or small chunks, broken separated fibers, or finely chopped pieces. Depending on which portion of the coconut shell is used and how it is processed coir has different qualities of water-holding and absorbency. It holds its structure longer than peat moss so it can be re-used a number of times and can help maintain long lived plants such as mothers or slow flowering sativas. I recommend using different coir products for the entire base since they can be processed for different water- and air-holding qualities. However, most of these coirs are not readily available, so we will use the standard coir fiber available in shops and blend it with perlite and vermiculite.

Making compost: Twigs and other partially composted material are returned to the bin for further decomposition. Any stray plastic or debris is removed.

Perlite is made by heating volcanic hydrated obsidian glass. When it is heated to about 1500ºF, the water in the mineral evaporates and the glass expands into a porous lightweight state, much like what happens to popcorn. The expanded material does not absorb water but holds drops of water on its irregular surface. It keeps its structure in the mix to provide air spaces for water movement. It is chopped to pieces ranging from sand to pea size.

Vermiculite is made from silicate clay that is exfoliated using heat. The mineral naturally forms thin layers on top of each other that expand when heated, creating spaces between the layers that hold both water and air. It has a high cation-exchange capacity so it buffers acids well and helps keep the mix balanced. The mineral is soft and somewhat spongy when compressed. It has been used for growing for more than 50 years.

The compost process uses both bacterial and fungal decomposition as well as sowbugs. and red worms (as shown above).

I recycle all my food waste including flesh into my compost pile. In addition, I use green garden waste such as weeds and dried leaves including processed cannabis leaves. The pile, actually two one-cubic-yard compost containers, processes the waste over a two-year period. First one container is filled. This is done gradually as the garden and kitchen yield ingredients to compost and takes about a year. Then I start to fill the second bin. After I add a layer of new waste to this container I take the top layer of compost from the first container then cover the new additions with dried garden leaf and debris. I add new layers almost weekly.

While the active pile is composting the size of the material shrinks so that at the end of the second year the second pile is filled and two thirds of the aging compost has been used to cover the new pile. This leaves a pile of mature aged compost of about one third a cubic yard or nine cubic feet. A cubic foot is equal to 6.4 gallons. I sieve this compost through a half-inch framed screen to remove larger particles, leaving only grit-sandy compost that contains some dead plum pits. The pits don’t deteriorate for a long time and they provide some larger particles to the mix.

The pile is active and heats up a bit at times, but not to the pasteurization temperature of 160ºF. However, there is a large community of worms that turns the compost partially into worm castings. The nutrients they contain are readily available and are enriched with helpful enzymes while passing through the worms’ digestive systems.

The additives you will need for your cannabis planting mix

Additives: Activated charcoal, Alfalfa meal, Bat guano, Coffee grounds, Greensand, Iron-Zinc-Manganese chelates, Kelp meal, Mycorrhizae mix, Soft rock phosphate, Trichoderma, Volcanite Rock Dust®

Plants in commercial planting mixes at Dennis Peron’s garden in San Francisco. Dennis uses mostly smaller containers so he can move them around to follow the sun. He re-uses the planting mix, adding new material each time.

Helps buffer the mix by absorbing excess nutrients and chemicals and may have other benefits in keeping the mix adjusted. Charcoal is associated with healthy plants.

Contains 2.5 percent Nitrogen (N) as well as 1 percent Phosphorous(P) and 1 percent Potassium(K). It also contains natural plant regulators such as triacontanol.

Contains readily available N as well as small amounts of P and K. (I recommend using any combination of guanos including bat, seabird and cleaned poultry manure, to obtain high amounts of N and P.)

Contains 2.2 percent N as well as minor amounts of P, K, Magnesium (Mg) and Copper (Cu). The nutrients become available over a period of several months.

Contains 25 percent Silicon (Si), 15 percent Iron (Fe), 7 percent K, 3 percent Magnesium.It is a sandstone called glauconite, the name given for iron-rich silica minerals. It gradually weathers, releasing its nutrients.

Chelated minerals increase the content of these minor nutrients quickly.

Contains 3 percent N that releases gradually.

These are the beneficial fungi that develop symbiotic relationships with the roots. They form a major portion of the rhizosphere community surrounding the roots.

This is a fast acting fertilizer that provides needed P to the soil. Bird and seabird guanos can be substituted with each other or with cleaned poultry manure (3-2-1) or insect frass to build up N-_p_K values.

SOFT ROCK PHOSPHATE—0-12-0

Contains an insoluble but easily available source of phosphate as well as an equal amount of lime. It gradually releases the nutrients as the plant uses them.

Trichoderma is a species of very active fungi which protects plant roots from pathogens. They are found in the product RootShield®.

VOLCANITE ROCK DUST®

Contains a combination of rock dusts including granite and minerals. Rock dusts seem to enhance growth and plant vitality.

Ed Rosenthal’s step by step planting mix recipe will provide your cannabis roots with a healthful environment that promotes a vigorous marijuana plant.