Cannabis Growing Mediums: Soil, Coco Coir, and More

Your plant cannot move around and find a comfortable place, unlike your cat which usually ends up perching on your laptop for comfort. Your cannabis plant will be fixed to one spot, anchored to a growing medium.

The growing medium serves many purposes. It anchors your plant and holds it up, especially when it grows bushy nugs. Additionally, the medium supports your plant's root system by giving it all the nutrients, water, and oxygen. 

But the process of choosing a medium isn't so simple — you need to pick a medium that suits your growing setup, preferences, and local conditions. This is why we have created this list containing the most popular growing mediums for cannabis with their benefits, drawbacks, and basic steps to use them. 

1. Soil

The easiest and cheapest way of growing cannabis is with soil — it is how plants have grown for millions of years, so you rarely go wrong with it. 

Despite having various alternatives, soil still isn't a poor-yielding medium. If you use it right, you can grow high-quality cannabis that often offers a better experience than its hydroponic counterparts. 

Another thing that makes soil so great for most growers is that it is easy to work with and relatively forgiving. You can make a few mistakes occasionally, and your cannabis plant will still yield good results. 

Pros and Cons of Using Soil as a Growing Medium for Cannabis

Here are some of the biggest benefits of soil as a growing medium for cannabis:

• Since it is easy to work with and forgiving, the soil is the best medium for new growers. 
• Soil serves as a physical support system for the plants to grow, anchor, and develop strong roots.
• With high-quality soil, pH fluctuations are rare.
• Soil contains a diverse microbial life that breaks down organic matter and provides nutrients to plants.
• Soil contains nutrients including nitrogen, phosphorus, and potassium that are essential for plant growth. Most commercial soils available in the market have enough nutrients to sustain your plants for a couple of months 
• Due to the ability of soil to retain moisture, plants can access water even if you don’t water them for a little while.
• Since soil is found easily and locally, it is typically less expensive than hydroponic or aeroponic systems.
• If you want to grow cannabis naturally and organically, nothing beats soil 
• Many growers believe that cannabis grown in soil often tastes the best 

But there are some drawbacks to using soil, too, such as the following:

• Soil often has a higher risk of mold, fungus, or pest infestations.
• The quality of the soil you purchase can vary greatly depending on the location, and in some cases may not be suitable for growing plants. You need to pick the right type of soil; the wrong type can lead to subpar plant development and health.
• You can’t control the growth of the plants in soil with precision, unlike hydroponics. 
• Since soil is less controlled, the plants may produce a lower yield (although high quality).
• For the same reason, cannabis may also grow slower than expected. 
• Typically, you’ll need more space if you want to grow plants in soil compared to plants grown using hydroponic or aeroponic systems.
• It’s better to grow plants in hydroponic systems if you want to help the planet in your own way. This is because soil can degrade eventually due to intensive farming which often leads to soil erosion, nutrient depletion, and other environmental problems.

Best Soil for Growing Cannabis

As mentioned above, not every soil type is suitable for the cannabis plant, so you must pick the optimal soil depending on your cannabis strain, growing conditions, and climate. 

Here are some common traits that you need to look for:

• The soil should be light and loose in texture to promote root development and oxygen retention, respectively.
• The soil must also have a decent draining ability so the water doesn't pool within the soil, which can lead to mold or subpar yields. On the contrary, it should still retain a little water — the balance is crucial here.
• Cannabis prefers soil with a pH ranging between 6 to 7. 
• The soil should also be rich in nutrients, but this is not essential as you can supplement more nutrients using fertilizers, compost, worm casting, etc. 

Using Soil to Grow Cannabis

Using soil to grow cannabis is pretty easy and straightforward. Once you choose the right soil for your cannabis plants, spread it on the garden bed or in a container, ensure its pH is stabilized, and add the necessary nutrients.

Then, you can germinate the seeds using any method you like and transplant the little seedlings into the soil. Beyond this point, provide the right conditions, light, and nutrients, and monitor your plant for any pests and diseases — your plant will grow well.

2. Perlite and Coco Mix

Perlite and coco coir are terrific growing mediums for cannabis, but individually, they don't work so well. Ideally, growers prefer to use a perlite and coco mix to grow cannabis. But what are these growing mediums, and how can they help? Let's dive in a little deeper.

Perlite

Perlite is made from obsidian, a type of volcanic rock that is mined, crushed, and heated to extreme temperatures, which makes it devoid of any moisture, and the compound expands rapidly. 

The result is an inert compound that is light and air — it almost looks like popcorn — and offers tremendous benefits like excellent oxygenation, no interaction with the nutrients, and low weight.

On the flip side, it has a couple of drawbacks that make it difficult to use on its own to grow cannabis. It has poor water retention, requiring you to water often, and you need to frequently test its pH range since it can fluctuate easily.

Coco Coir

On the other hand, you have coco coir, which is made from coconut husks and resembles peat moss. This eco-friendly growing medium functions like soil, offering excellent benefits.

Coco coir has decent water and air retention, allowing the roots to access nutrients easily and grow better. Additionally, it requires smaller pots without hampering the plant's size, and it is difficult to overwater. Lastly, it is forgiving, making it ideal for new growers.

The downside with coco coir is that it lacks any nutrients, so you need to supplement them. Also, coco coir needs to be soaked in water before you use it. 

Perlite and Coco Coir Mix

Both perlite and coco coir are light materials, so when you mix them, your plants get the advantage of easy root development thanks to the low density. The downside is high water drainage. You might think this is bad for water retention, but you’d be wrong.

Although both materials are similar in consistency and shape, they work quite differently from one another. 

The benefits of perlite and coco coir mix are as follows:

• The mix allows you to grow massive plants that yield well. 
• You get to control the nutrient levels as per your cultivation goals. 
• You don't need to invest in any special equipment related to the growing medium except for a pH meter. 
• The mix is almost as easy as soil to grow cannabis.

Here are some of the downsides of this mix:

• Since it lacks any nutrients from the start, you need to supplement and monitor the nutrient levels regularly from day 1.
• You also need to monitor the pH levels constantly.
• Sourcing this mix may be difficult in some regions, but it is available online in most areas for a decent price.

Creating a Perlite and Coco Coir Mix

Perlite and coco mix are easy to create and work with — only slightly more difficult than soil. And creating a mix is relatively straightforward. Here is how to create your own perlite and coco mix at home.

• Creating the Mixture

The first step is to create the mixture — sounds easy, doesn't it? Get your hands on some perlite and coco coir and mix them. You do need to keep the ratios in mind, though; ideally, you should always use more coco coir. 

Stick to a coco-to-perlite ratio of 60:40 or 70:30, depending on your growing conditions and goals. 

Once the mixture is ready, place it in a new pot and transplant your cannabis seedling. Over time, the mixture may settle, so you can add more perlite and coco mix to maintain the appropriate volume of the growing medium. 

• Perlite and Coco Mixture with Compost

Additionally, it is also recommended to use some compost since the two materials lack any nutrients to support the plant. The addition of compost will give a much-needed nutrient boost. 

You can also use other organic soil amendments to boost the nutrient levels in the growing medium. The best choices include bat guano, kelp meal, fish emulsion, blood or bone meal, manure, alfalfa meal, and earthworm castings. 

3. Expanded Clay Pellets

Clay pallets are also known by other names like hydroton, clay pebbles, and lightweight expanded clay aggregate (LECA). These small balls are made by expanding and heating clay, a process that makes them very porous and lightweight. But they are still heavy enough to support a bushy cannabis plant.

This process of expanding and heating makes these pellets great growing mediums that have excellent aeration that supports root development and water retention. Their nature makes them ideal for hydroponic cannabis cultivation. 

Here are some of the benefits of expanded clay pellets:

• Thanks to their porous nature, they can retain a lot of oxygen, allowing the roots to expand a lot more.
• They are less likely to develop blockages, ensuring the water drains efficiently and does not pool up.
• Since they have a neutral pH, they can also harbor microbial populations — something that's not always easy with other grow mediums. 
• You can easily reuse or recycle them for the next season. 

However, they also have some downsides, such as:

• Their water holding capacity isn't that great — it's decent at best — you may need to water this medium more often.
• Currently, clay pellets are fairly expensive in most regions unless you find a good deal on them.
• Over time, they can cause plumbing problems in your hydroponic setup if they make their way into the system. 

Tips on Using Expanded Clay Pellets

Using clay pellets isn't as easy as using soil, but they are still suitable for novice growers. Follow these tips to use clay pellets to grow cannabis:

• Rinse Before Use

Clay pellets can potentially cause blockages or plumbing issues in your reservoir plumbing, so you need to rinse them first to remove any dust and debris. For this, you need to place them in aerated water for up to 24 hours. 

• Add the Nutrients

Even before you start growing cannabis, you need to add nutrients to the pebbles since they otherwise lack any nutrients. This nutrient bath will prepare the pebbles by saturating them with essential nutrients.

For this, you must place the pebbles in a pot and add the nutrient solution. Make sure the nutrient solution has an EC of 0.4. You will need an EC meter for this, so get one. It's worth it. 

• Rinse Them Often

After rinsing and saturating them, your clay pellets are ready for use. Simply plant your cannabis seedlings in them and stick to the watering routine, and your plant will flourish. 

However, the pellets cannot nourish your plants forever and can develop high EC values quickly. So, you need to rinse them regularly, especially if you see a white tint or salt residue forming on them. 

Follow the same steps above to rinse and renourish them with pH-neutral water and nutrients, respectively. This will keep the pellets full of nutrients without risking phytotoxicity in your cannabis plants. 

• Do Not Crush the Pellets

Many new growers make the mistake of crushing their clay pellets, but you’re better off avoiding that. Crushing the pellets affects their oxygen and water retention capabilities since their pores get diminished. 

If you do need to crush them, for example, when using a net pot, do not compress them too much. Doing this will not only impact aeration and water retention, but they may also pass through the net and get into your reservoir plumbing.

4. Rockwool

Rockwool is a fascinating growing medium, and it offers a relatively high difficulty of use, depending on your setup, and costs slightly higher than soil. 

This medium was initially used in construction as an insulation element but has recently become a favorite for many growers. It is made from basalt salt, which is heated to extreme temperatures and spun into a cotton-candy-like material. 

Thanks to this, Rockwool has tremendous water retention, making it an ideal growing medium for a cannabis hydroponic setup. 

Here are some of the benefits of Rockwool:

• Rockwool is sterile, so the risk of diseases, pests, and infestations is quite low. 
• Like coco coir, Rockwool also gives you tremendous control over the nutrient and pH levels, so you can fine-tune the nutrient regimen as per your goals and preferences. 
• Since Rockwool is often sold as cubes, you can use them to germinate seeds and transfer the cube to the final container instead of removing the seedling and transplanting it — this is safe and hassle-free for new growers.

And here are some of the downsides of Rockwool:

• Since it is inert, you need to add nutrients to it even before you add your plant.
• You must monitor the nutrient and pH levels regularly to ensure it has enough nutrients to nourish your cannabis plant.
• Rockwool is not organic — it is not a natural material and does not biodegrade well, and recycling it is also a bad idea. Plus, the manufacturing process may not always be eco-friendly.
• Before using Rockwool, you also need to soak it in slightly alkaline water. 

Using Rockwool to Grow Cannabis

Using Rockwool may initially seem difficult, but once you know the right method, it is pretty straightforward. Follow these steps to use Rockwool to grow cannabis:

1. Place your Rockwool cubes in slightly acidic water (pH ranging from 5.5 to 6.5) for a day to balance the pH. 
2. After a day, remove them and gently squeeze out the water. 
3. Make a 1-inch incension on top of the cube with a pen or something sharp. 
4. Place a seed in the hole and let it germinate. 
5. Place the cube in a container with drainage holes.
6. Keep watering the cube regularly to keep it moist and maintain the ph between 5.5 to 6.5. 
7. Once the seedling has grown about three inches, you can transplant the cube into a larger container. 

Note that Rockwool can irritate your skin and lungs, so always wear gloves and a mask while handling it. 

Tips for Using Rockwool

There are still a lot of intricacies to using rockwool, which calls for an entire guide on this subject, but to give you a better idea, here are some tips on using Rockwool to grow cannabis:

• Make sure the Rockwool is stabilized to the right pH range before you use it. To do so, test the runoff water's pH — if it is around the recommended pH, it is stabilized.
• You can also clone cannabis using Rockwool — place your cutting into a prepped Rockwool cube and let it grow. 
• It is recommended that you use an automatic irrigation system for your Rockwool, or you may have to water it multiple times a day. 

Follow these tips to grow a healthy, flourishing cannabis plant with Rockwool.

How to Choose the Best Growing Medium to Grow Cannabis?

These are only some of the best-growing mediums for cannabis; there are many more. And it can be difficult to narrow down on the best-growing medium — there isn't a single best one, but only what works best for you. 

But, how do you know which is the best for you? You need to consider a few factors, such as the following.

1. Growing Method

The first thing you must consider is your growing setup, so you can pick a growing medium that suits it. For example, most hydroponic systems require a medium with high moisture retention and drainage, where clay pellets or Rockwool work best.

2. Water Retention and Aeration

Similarly, you also need to consider water retention and aeration. Cannabis is a thirsty plant, but too much water can lead to root rot, and at the same time, the growing medium must provide enough aeration so the roots can develop well.

When choosing a growing medium, consider these factors in tandem with your local climate and set up to find a medium that works best for your conditions. 

3. Nutrition

Cannabis also requires a lot of nutrients. If you want a massive yield, you must be meticulous about the nutrients. Fortunately, the soil is a medium that is rich in these nutrients, so you don't have to worry much.

On the other hand, other inert growing mediums like Rockwool or perlite are devoid of any nutrients, and you need to supplement nutrients. Choose these inert mediums if you are okay with it since adding more nutrients takes some effort, research, and a slight amount of money.

4. Ease of Use

You must also factor in your skills and how much work you are willing to invest in your growing medium. If you’re a new grower or want something straightforward, go with soil — it is easy to maintain. 

If you’re relatively experienced in gardening, you can choose other mediums that require some preparation and processes before they are ready to be used. Some even require regular maintenance along the way.

5. pH Levels

Some growing mediums have a stable pH, like soil. In contrast, others are a little difficult to maintain — it is easy for the latter to experience pH fluctuations due to slight discrepancies in water or nutrients. 

Choose a growing medium that works for your setup in terms of pH.  It is an easy process but does take some time, especially if you have to balance the pH.

6. Sustainability

Lastly, you need to consider the environmental impact of your growing medium. For example, soil and coco coir is organic and will not damage the environment, but the same can't be said for mediums like Rockwool. 

This doesn't mean Rockwool or similar mediums are bad; they just might not align with your ideals. 

Summary: Cannabis Growing Mediums: Soil, Coco Coir, and More

There are various growing mediums you can choose to grow cannabis. Which one will your cannabis plant like the most? That's one thing that you have to decide. But this article has given you the right information to make an informed decision. 

If you’re a new grower, want the most natural route, or don't want to put in a lot of effort, you can opt for soil. Just make sure the soil is healthy and the right kind for your cannabis plant. 

If you’re a confident grower but want something different, especially if you are growing hydroponically, you can use a perlite and coco mix. It offers various benefits while being easy to work with. 

Lastly, you can use clay pellets or Rockwool if you are growing a hydroponic plant or want to push your cannabis plant to its limits. These growing mediums are somewhat difficult to work with but allow you tremendous control over the feeding regimen, so you can fine-tune them as per your goals. 

In any case, do adequate research before deciding and follow the right steps. The right medium will feel like home to your cannabis plant, and it will flourish unlike ever before.