best growing medium for indoor cannabis

You can eliminate the need for a growing medium by choosing a hydroponics setup. After you have purchased the start-up equipment, you may only require nutrients and water. If you only want a small cannabis garden, it is possible to buy an entire system for under $150.

This is among the most popular non-soil growing mediums around, especially amongst commercial growers. It is a mixture of slag and melted basalt rock. You use a Rockwool ‘block’ to start seeds, and it can support the growth of a plant right until it is ready for harvest.

Another factor that reduces the price is reusability. If you use a standard potting mix, the nutrients are used up after a single crop. As a consequence, you need to begin the next batch with fresh soil. However, certain substrates last several harvests. You will still need to add nutrients, but the overall cost is lower for growers intent on cultivating cannabis regularly.

You will likely find slabs of coconut coir for a similar price as a reasonable potting mix. The primary difference is that you must also purchase nutrients. As your plants require the food immediately, it means buying added nutrients right away. Coco Coir is coconut fiber, often remaining from processing coconut for consumer goods.

However, one must not overlook the growing medium your plants use. It is, after all, what your plants grow in. As long as their roots have room to grow, and consistent access to fresh water, oxygen, and the correct level of nutrients, your plants should thrive. Nonetheless, a growing medium makes a difference in the overall growth of your crop. An unsuitable medium could provide the wrong (or inadequate) nutrients or fail to drain correctly. It could also attract an increased number of pests, or impact how quickly the plants grow.


Inert growing mediums such as coco coir, Rockwool, vermiculite, and perlite, also require nutrients. However, you can reuse them several times. If you get a great deal on the nutrients you purchase, you could save a significant amount of money.

Ultimately, the most inexpensive and costly growing mediums depend on several factors. Those who intend to cultivate numerous plants regularly will save money on a medium that proves pricey for the casual, occasional grower.

As nature’s growing medium, one would expect to pay the least for soil. If you can grow outdoors in fertile soil, you already solve a significant problem. However, most people cultivate cannabis indoors and must buy the soil. As for price, the truth is, you will likely see enormous differences depending on the brand.

If you buy a cheap hydroponics system, you could come out ahead after a few grows. Aside from the initial start-up costs, all you need are nutrients and water.

This is becoming an increasingly popular soil additive. Made from volcanic rock, vermiculite is a much-loved hydroponic medium made from volcanic rock. In general, it is cheaper than other common options, such as Rockwool and Coco Coir. It does an excellent job of holding on to moisture. As a result, you use less water. When heated, vermiculite expands significantly, and it is very lightweight. This inert substrate is insoluble in water, so it absorbs enormous amounts of it.

It doesn’t mean the ‘big name’ soil is better quality than the brand you’ve never heard of. You should find enough ‘regular’ soil to fill 12 gallons worth of pots for less than $35. Better options include enough nutrients for a few weeks. Then, you can pay another $25 to purchase more nutrients. Ultimately, you have paid $50-$60 with some nutrients left over. For your next grow, you only need to buy soil until the existing nutrients run out.

Aside from the initial costs of vermiculite and perlite, your overall running costs are similar to those associated with a ‘water only’ hydroponics setup. You can reuse them many times, and also benefit from a lower risk of pests in your crops.

There’s a lot more to finding a cheap medium than the initial price you pay! First and foremost, a medium that contains nutrients instantly saves you money. Let’s imagine that there are two options: A potting mix for $10 you found on sale, and a super soil mix that costs $40.

Cheap potting soil requires nutrients, but you could save cash if you plan on overseeing several harvests. You can use the leftover nutrients for your next grow, for example. Also, even low-cost soil should have enough nutrients to last for a few weeks.

Vermiculite & Perlite.

However, it is inert, which means you must add nutrients, so the initial cost is relatively high. As its rate of water retention is significant, you must ensure it has adequate drainage. Rockwool also has a high pH, so you need to check the root zone regularly.

Perlite is also made from expanded volcanic rock. However, it is light, airy, and allows for excellent drainage. As a result, people often add perlite to their container grows. In general, growers tend to use a combination of the two, rather than relying on one or the other. A lot of individuals also like to use perlite and coco coir together.

At this stage, all you need to do is pay for nutrients and electricity. First-time growers are often frightened of hydroponics, but the process is much simpler than you think. As you only need to refill your tank every few weeks, the nutrients you purchase could last a long time. Whether the process is cheaper than the others depends on the cost of nutrients, and the number of plants you grow.

While ‘clean’ Coco tends to keep pests at bay, the challenge is finding it. Most Coco Coir comes from Sri Lanka, India, Brazil, Thailand, and Mexico. Make sure you only purchase it if there are lab tests to prove its quality. The best brands triple test theirs: At the source, as it enters the United States, and before it gets packaged.

This ‘just add water’ method often produces outstanding marijuana plants. However, you will likely pay around $100 for 12 gallons of pots. Moreover, you must pay this sum for every crop. Therefore, we recommend that you shop around. You may find that regular potting soil plus extra nutrients are a little cheaper than a super soil mix.

It offers water-resistant insulation while still enabling a greater level of water retention in a hydroponics system. As a result, more water remains trapped inside the block and is easily accessed by the cannabis plants’ roots. Rockwool is fibrous, so it permits a greater level of aeration. In simple terms, the roots find it easier to locate oxygen.

Potting Soil.

Option A is $30 cheaper, so is it undoubtedly the best option? It depends . The expensive soil likely contains all the nutrients your plants need. As a result, you don’t need to do anything else other than add water. If the cheap potting mix doesn’t contain nutrients or only has enough for 3-4 weeks, you need to purchase more nutrients. Suddenly, after paying $50 for what your plants need, you are $20 behind!

That said, the actual medium doesn’t matter that much regarding the quality of buds. This is assuming it provides the right level of drainage and nutrients. As a result, this is one area where you could save a few dollars. In this guide, we check out the different growing mediums available and help you decide which one is right for your bank balance.

We recently looked into growing cannabis on a budget and found it was theoretically possible to enjoy a small harvest for under $200. For many new growers, cultivating marijuana without spending a fortune is an important consideration. The most expensive aspects include lighting, air circulation, and nutrients.

When growing cannabis with soil, use loose, non-peat based potting compost. Ideally, it will also include up to 30% of perlite, or another soil ‘conditioner.’ This should ensure adequate drainage to ensure there are higher amounts of air/oxygen in the soil. As a result, your plants should grow even faster. However, they tend to grow slower than if you use a hydroponics system or coco coir as your growing medium. On the plus side, soil-grown weed tends to have a stronger taste and a more pungent smell.

It is a popular option for individuals that use hydroponics systems for their plants. For experienced growers, having the chance to control their crop’s life cycle is perfect. Coco Coir is light and enables lots of oxygen to reach plant roots. As a bonus, it is a ‘sustainable’ growing medium. It is less prone to pest infestations, and you can reuse it up to three times. You still need to buy nutrients, but you could save money in the medium-term. Also, cannabis grown in Coco usually grows to a very high standard.

Overall, super soil is arguably the most expensive because the costs don’t reduce over time. You always need to buy everything from scratch. On the plus side, you don’t need extra nutrients, so those using expensive versions at present could actually save money. As you only need to add water and occasionally monitor your plants, super soil is an excellent option for the novice.

When you use living soil, microorganisms in it create an ecosystem. The nutrients get broken down and go directly to the roots of the plant. There is no need to add any nutrients to this form of soil. On the downside, plants growing in living soil take longer to mature. Also, the smell of composted soil in the house isn’t particularly pleasant for most people!

That being said, let’s take a quick look at a few of the most popular mediums for indoor gardens:

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!

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.


A gray-white mineral mined from volcanic lava flows, perlite is also heated and expanded into small, sponge-like kernels that are extremely lightweight with decent water-retention properties of three to four times its dry weight. Its best feature is that it is very neutral with a pH of 6.0 to 8.0. Unlike vermiculite, perlite has no cation exchange capacity and therefore is poor in buffering. This is why perlite is often used as a spread on top of soilless mediums to help keep moisture locked in below.

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.

Are you a novice cannabis cultivator looking for a guide to grow mediums for indoor marijuana growing? Well, you’re in luck. High Times Cultivation Editor Nico Escondido answers all of your grow questions in his weekly Nico’s Nuggets column, and this week, he’s focusing on grow mediums for indoor growers.

A soilless, peat-based mixture with perlite mixed in.

Most commonly known as Rockwool (a brand name), mineral wool is an extremely popular medium for rooting and growing plants, especially in heavy hydroponic systems. Spun from fibers created by melting various rock types, the “wool” is then pressed into various plugs, squares and slabs for growing plants. Mineral wool will hold a considerable amount of water while also allowing for good air permeation. Mineral wool is sterile and inert with a neutral pH, however, it has poor buffering and is generally regarded as a medium for advanced growers.

Obviously, choosing one of the above mediums hinges a lot on the type of grow system being used in the garden. In terms of the question posed, I would concur that for a first-time grower, using a soilless mix (such as Sunshine #4 or Pro-Mix) and utilizing a daily hand-watering regiment is the best option.

Thanks for writing in Carlos & Melinda—and congratulations on starting your first grow! That is music to our ears here at High Times!

The Question: What Grow Medium Is Best For New Indoor Growers?

Correct medium choices help genetics reach their potential as seen with this pink Jah Goo.

There are three types of peat used in agriculture: peat moss, reed sedge and peat humus. Peat moss is the most widely used and is derived from sphagnum and other mosses, varying in color from tan to dark brown. Peat has a high moisture-retaining capacity, being able to hold 15 times its dry weight in H2O, and contains small amounts of nitrogen. However, it has high acidity with a pH range of 3.2 to 4.5. Peat is almost always used in soilless mixtures, rather than as a stand-alone medium, with sphagnum, perlite, wood chips and coco being its primary partners.

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.

Hardened expanded clay (HEC) being used in a flood-and-drain hydro table.

To start, whenever discussing indoor grow mediums, I think it is important to differentiate between “soil” and “soilless” mediums. When we, as growers, talk about using soil indoors, we are actually talking about what is commonly known as “soilless” mediums.

Hardened Expanded Clay (HEC)

— Carlos & Melinda, via the mailbag at [email protected]

Actual mineral soil or topsoil is rarely, if ever, used indoors anymore (excluding greenhouse grows). This is simply because there are now better options that can do the same thing as mineral soil. These “soilless” mixtures are peat- or sphagnum-based. When one considers that real earth soil is generally not sold as a sterilized medium and may contain pests, molds or possible diseases/viruses embedded in it, the risk of bringing that into an indoor garden is not worth it—especially when these moss-based mediums look, feel and act very similar to actual soil.

Chemically speaking, vermiculite is hydrated magnesium-aluminum-iron silicate. It expands quite a bit when heated, and once expanded, it is extremely lightweight. It is insoluble in water, inert and can absorb huge amounts of water, which is why it is often a key ingredient in soilless mixes. Furthermore, its high cation exchange capacity makes it very good for buffering and use with heavy nutrient programs.

For those with previous experience looking to use a hydroponic system, soilless mixtures are still good for top-feed or drip-irrigation systems. Once you move into the more advanced hydro setups, such as flood-and-drain tables, deep-water culture (DWC) or nutrient film technique (NFT), mineral wool and HEC become better choices.

Remember, whichever way you go, be sure your root zone is easily permeated by air so that roots can get the oxygen they love so much. And when it comes to buffering and choosing your nutrient program remember—less is more, as you can always up your dosages, but correcting a nutrient overload is much more difficult.

Best Smell/Taste Profile:

Least Chance of Bugs/Pests:

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.

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!

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

Common Cannabis-Friendly Coco Coir Mixes in the US:

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

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


Allow me to explain…

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.

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.

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

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!

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.

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.

Best of the Best: Grow Medium Roundup.

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

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.

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!

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.

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

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

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!

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

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.

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.

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

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

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!

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).

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.

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.