When it comes to growing cannabis indoors, the foundation matters. Sure, you may have splurged on the highest quality seeds, LED lights, and hydroponics system. But if you’re not using the right soil for growing weed, you might end up with a harvest that doesn’t live up to your expectations.
The success of your grow operation can be traced all the down to the soil beneath your plants. Buying the right soil will not only improve the quality of your plants but can also make it easier to manage your grow operation as a whole.
You might be thinking, “how many types of soil could there possibly be?” The answer might surprise you.
Luckily, you can avoid all of the headaches of trial and error because we’re breaking down the best types of soil for growing marijuana indoors.
last updated: February 12th, 2020
|PRODUCT NAME||PRIMARY INGREDIENTS||PH ADJUSTED|
|CannGrow||Bark Fines, Compost, Diatomaceous Earth, Worm Casting, Perlite, Pumice, Peat, Coco Coir, and Biochar||Yes|
|Foxfarm Ocean Forest||Moss, Forest Humus, Crab And Sea-Going Fish Meal, Bat Guano, and Earth Casting||Yes|
|Organic Super||Guano, Kelp Meal, Alfalfa Meal, Fish Bone Meal, Blood Meal, Aloe Vera, Coconut Husks and Coconut Water Powder, Epson Salt, Azomite, and Dolomite Lime||Not Stated|
|Foxfarm Happy Frog||Forest Humus, Bat Guano, and Earthworm Castings||Yes|
|Espoma SS8||Earthworm Castings, Peat Humus, Perlite, Sphagnum Peat Moss, and Limestone||Not Stated|
Top 5 Soils for Growing Marijuana
#1 CannGrow Premium Cannabis Soil Mix
CannGrow Premium Cannabis Soil Mix was rated one of the best soils for growing weed in 2019, and for a good reason. The soil uses a natural blend of bark fines, compost, diatomaceous earth, worm casting, perlite, pumice, peat, coir, and biochar. It also incorporates mycorrhizae to increase the organic value of the soil. It features a light and aerated texture, which contributes to how well good cannabis plants thrive in this soil.
One of the best things about the CannGrow Premium Cannabis Soil Mix is that it doesn’t require virtually any prep or knowledge of how to use soil. It’s ready to use right out of the box. Just open the box and pour it into your grow container, and it’s ready to go.
Overall, it offers a great combination of water retention, drainage, and aeration that cannabis plants need to thrive. The presence of the biochar within living soil reduces water loss and fertilizer intake frequencies to that it requires less maintenance over time.
What We Like
- Contains biochar, eliminating the need for fertilizers
- Organic elements add an extra layer of aeration and create a light texture
- Offers a superior combination of water retention, aeration, and drainage
- It is compatible with different growing containers
What We Don’t Like
- It can be expensive compared to other brands of soil
#2 Foxfarm Ocean Forest Garden Potting Soil
Foxfarm Ocean Forest soil is a great option for any indoor cannabis growers looking for an all-in-one soil and plant nutrients. It’s a bit unusual compared to other soils because it uses a blend of unique ingredients like moss, forest humus, crab and sea-going fish meal, bat guano, and other earthy elements.
Unlike some of the other soils on the market, Foxfarm soil is pH adjusted from 6.3 to 6.8. This ensures optimal fertilizer uptake, which makes your plants grow healthier, with less work on your part.
This soil is specifically formulated to include all of the nutrients and plant food that your seeds need, without having to add additional nutrients and fertilizers. It works extremely well when using a small grow box or if your grow area is on the small side.
What We Like
- pH adjusted from 6.3 to 6.8 for optimal fertilizer intake
- Contains a powerhouse blend of natural materials
- Does not require you to use nitrogen fertilizers
- Promotes branching and healthy plant growth
What We Don’t Like
- The way the soil is packaged has posed issues for a lot of users who claim that their bag arrived damaged because the packaging is very fragile.
#3 Organic Super Soil Concentrated Strength
Organic Super Soil is a fan favorite because it offers a very straightforward option for indoor marijuana growers. Like some of the other good soils on this list, it also includes some very unique ingredients to promote healthier and more potent plants . These ingredients include bat guano, kelp meal, alfalfa meal, fishbone meal, blood meal, feather meal, Aloe Vera, coconut water powder, Epson salt, azomite, and dolomite lime. The soil also contains a number of rare microorganisms, including Glomus etunicatum, Glomus aggregatum, Trichoderma, and Pisolithus Tinctorius, to mention a few.
While this might sound like gibberish, the presence of these elements and organisms can make a hugely positive impact o your plants and cause your plants to require much less hands-on maintenance. Basically, all you need to do is keep them watered and properly lit, and the soil will take care of the rest for you.
One of the downsides of this soil is that the number of microorganisms causes it to have a very strong smell. If you’re using an indoor grow tent or a smaller grow space, then it’s recommended to add a carbon filtration system to try and eliminate some of the odor of the soil.
What We Like
- Numerous microorganisms for superior microbial action
- Soil pH remains within the normal range when you use rainwater
- You may not need fertilizer, thanks to the super ingredients
- Ready to use with containerized planting
What We Don’t Like
- It smells very bad and requires a carbon filtration system to reduce the odor
#4 Fox Farm Happy Frog Potting Soil
Foxfarm soil makes another appearance on this list, which should tell you how much we enjoy the quality of this brand of soil. The Foxfarm Happy Frog Potting Mix takes its standard topsoil and adds in more of the necessary fungi and microbes required for breaking down organic matter. Like their other soils, this blend also includes high-quality ingredients, including forest humus, bat guano, and earthworm castings for ultimate growth performance.
Foxfarm guarantees that the Happy Frog blend creates a dynamic vegetative stage growth, strong plant structure, and improved flowering stage and fruit production. Apart from being properly aerated, this growing medium has a fine texture with an adjusted pH for exceptional plant growth.
What We Like
- Presence of fungi and microbes for breaking down organic matter
- No fillers, only healthy ingredients are included
- Vigorous vegetative growth and strong plant structure
- Convenient for containerized planting
- pH adjusted for optimal results
What We Don’t Like
- Defective bags may contain fungus which could damage the outcome of the plants
#5 Espoma SS8 Organic Seed Starter
The last soil on our list is another fan favorite for containerized planting and small grow spaces. The Espoma SS8 Organic Seed Starter promises to help your plants grow twice as big as other soil brands. While we can’t 100% attest to this fact, most users do report that their plants appear fuller and more bountiful with this soil. It contains a soil mixture of earthworm castings, peat humus, perlite, sphagnum peat moss, and limestone. It also contains several active ingredients that aim to replace the need for fancy fertilizer, including Scleroderma citrinum, Scleroderma cepa, Rhizopogon luteolus, Rhizopogon fulvigleba, Rhizopogon amylopogon, and Pisolithus Tinctorius.
We also love that Espoma soil uses all-natural ingredients and that their soil is enhanced with myco-tone elements to improve posture retention in your plants so that they do not dry out as quickly. The myco-tone also works as a catalyst to enhance the active ingredients in the rest of the elements of the soil.
What We Like
- All-natural ingredients enhanced with myco-tone
- Fast and effective seed germination
- Promotes root growth
- Improves and increases water and nutrient uptake
- It is a starter mix that doesn’t require additional fertilizer
What We Don’t Like
- It does not state if the soil is aerated which means you may have to test the aeration levels manually.
What to Consider when Choosing Soil for Weed?
When you start researching the best soil for growing marijuana plants indoors, you might become overwhelmed with the results. There are hundreds of brands of soil that will work just fine for indoor growing. When it comes to the specific type of soil you should use for your own grow operation, there are a few different types of soil that are growing in popularity among weed farmers.
Popular Types of Soils for Weed
The most popular types of soils that you will come across include clay, silt, sand, and loam. Clay and adobe soils are still not as mainstream as stilt, sand, and loam, but that doesn’t mean you shouldn’t understand the benefits of each type before you make a final buying decision.
Most clay soils consist of essential nutrients that your marijuana plants need to thrive. The downside to clay soil is that it has a tight and sticky consistency which can make it difficult for the weed to absorb nutrients and to aerate the soil. The soil tends to be very compact which can prevent water from reaching the roots of the plant.
So when is clay a good option? If you have a high-quality hydroponic system as well as a way to make sure your soil stays aerated, then you shouldn’t run into any problems using clay soil.
Sandy soil is easy to use and tends to have excellent drainage compared to other types of soil. However, because it drains so well, you run the risk of some of the nutrients of the soil being carried away by runoff water. A lot of growers see this as very wasteful and also makes if pretty challenging to know if your plants are getting enough water and nutrients.
One way to bypass this challenge is to add additional nutrients to the soil by using special fertilizer or other organic materials to offset the number of potential nutrients being lost to runoff.
Loamy soil is a combination of clay, silt, and sand which creates a pretty ideal combination for growing weed. So it’s no surprise that loam is one of the most highly recommended types of soil among seasoned marijuana growers. It easily retains water and nutrients and doesn’t require much additional knowledge to work with. It’s a perfect choice for new growers or growers who don’t want to do a ton of research trying o figure out the best soil type to use.
Potting soil is an all-in-one rich soil option which usually includes all of the nutrients you need for a thriving weed plant. It’s the most common type of soil used in growing marijuana mostly because of its availability and popularity among all types of indoor and outdoor gardeners.
Most potting soils are formulated to retain water and nutrients and air out evenly, making them ideal for hands-off marijuana rowers. They drain well and allow for easy root penetration.
There are two types of potting soils: organic and conventional. Organic potting soil is eco-friendly since it contains worms, decaying plant material, and microorganisms that add minerals and nutrients. Conventional potting soil contains some non-organic elements, such as black hummus, manure, and peat. The most popular potting soils are soilless mixes which tent do be inexpensive, lightweight and sterile growing mediums and are commonly used in commercial nurseries. Generally, the mixes are made from a number of materials, including coconut coir, peat moss, sand, perlite, vermiculite, and pumice among others.
Tending To Your Weed Plant Depending on your Soil Choice
The right soil can help nurture your plants and all of their terpenes and cannabinoids. Before you choose which type of soil you want to use, you need to determine the needs of your weed plant. Look at things like the type of equipment you are using, the types of seeds you will grow and the size of your grow space. This will help you determine how much water your plants need, what kind of pH value the plants require, how much drainage you need, and what type of soil texture will work best for your plants.
Weed flourishes in well-drained soil with an adequate supply of water. Usually, the plant grows larger in an irrigated habitat but is stunted by aridity.
Standing water is quite harmful to weed, since the roots may easily suffocate. As a result, porous organic soil with high sand content and moderate slope seem best suited for proper growth. During germination, the seeds have to be in continuous contact with moist soil.
Choose the Right pH Value
The pH is a measure of how acidic or alkaline the soil is. Its scale runs from zero to fourteen, with seven considered a neutral pH level.
The pH determines the solubility of nutrients as well as affects the weed’s regulation of its nutrient uptake and metabolism. Slightly acidic soils with a pH that ranges from around 5.8 to 6.5 are great for marijuana plants.
The pH of the soil you choose affects nutrient solubility. Soils with a higher level of organic matter do usually contain nutrients that are soluble between 5.0 to 6.5 pH levels.
Nutrients tend to be quite soluble in slightly acidic to highly alkaline soils. Use a pH meter to accurately test the soil pH level.
Soil texture is normally determined by the physical state and size of the growing medium. The ideal soil texture is needed for effective root penetration, water retention, and drainage.
Soils that are made of fine mineral particles are adobe or clay. The particles in these types of growing medium do normally stick together tightly when wet, causing poor root penetration and water retention.
Sandy soils have larger particles, which allow for good aeration, root penetration, and drainage. However, they have poor water retention.
You can know the soil texture by picking up a handful of moist soil and then squeeze it gently in your palm. The soil should hardly stay together. Avoid growing mediums that stick together tightly.
Regardless of how well the growing medium is prepared, your soil needs to have good drainage. Clay or hardpan soils do not drain properly and could end up ruining your harvest if not used correctly.
Even if it’s your first time growing weed, there’s no need to feel intimidated by the options when it comes to your soil. For the most part, there are a lot of other factors in addition to the soil that impacts the quality fo your weed plants.
Start by considering the most basic factors, such as the soil type you think will work best for your grow operation. Look at things like the microorganisms, nutrients, pH, texture, water retention and other traits of the soil to determine which one is right for you.
We hope the toils on this list act as a baseline of knowledge for you as you continue learning all about how to grow marijuana indoors and find the solution that fits your growing needs the best.