Best soil for cannabis for higher yield and potency

• Brody Hall
• Nov 11, 2022
• No Comments

The quality of your soil influences everything from the size of your plants to the potency of your buds—which is why finding the best soil for cannabis is so essential. Your run-of-the-mill bag of dirt from a big box store won’t cut it. You need soil that has the right nutrient ratios, pH balance, and materials for cannabis cultivation.

There’s a lot to factor in during a soil search, but we’ve done the legwork for you. Below is a rundown of the best options on the market that your plants will love.

My top picks

Cannabis plants can be, well, a little picky when it comes to their growing environment. But these top-of-the-line soils have got them covered, delivering the perfect mix of nutrients, pH balance, and materials for a successful cannabis crop.

1. BEST OVERALL: Super Soil Autoflower Concentrate

This living soil is teeming with microorganisms and fungi that will deliver key nutrients to your plants from seed to harvest.

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Product Specs 

• Size: This bag comes with five pounds of soil mix.
• Type: This is an autoflowering, living soil that needs to be mixed with organic potting media.
• NPK: There is no NPK value listed because the microbes in the soil provide nutrients to plants as they need them.

Some cannabis growers like to DIY their soil, adding mixtures of various nutrients and amendments to create the perfect recipe for their plants. But if you want something a little less hands-on, look no further than Super Soil Autoflower Concentrate.

This all-in-one soil mix is alive with microorganisms that form a symbiotic relationship with your plants’ root system. This means that key nutrients are readily available to your plants throughout their entire life cycle, from seedling to harvest. As one reviewer who saw “very measurable gains” using this soil puts it, “mix, plant, water. That’s it.”

A hefty stench is the only downside to this almost set-it-and-forget-it soil mixture. But if you can get past the smell, you’re in for some seriously healthy plants—and a seriously chill growing experience.

2. BEST BANG FOR THE BUCK: FoxFarm Ocean Forest Potting Soil

With a rich blend of earthworm castings, bat guano, and micronutrients, this potting soil feeds your buds —without breaking the bank.

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Product Specs 

• Weight: The size of the bag is unclear, but it seems to be 40 quarts.
• Type: This soil is a mix of loam, humus, and moss.
• NPK: The NPK is not listed.

As any cannabis grower knows, high-quality soil doesn’t come cheap. But if you’re looking for a budget-friendly option that doesn’t skimp on quality, FoxFarm’s Ocean Forest Potting Soil is a great pick.

This nutrient-rich, organic mix is ready straight out of the bag —no amendments necessary. It’s made with earthworm castings, bat guano, and fish and crab meal from the Pacific Northwest that deliver vital nutrients to your plants’ roots.
Cannabis plants love this stuff, as evidenced by the thousands of happy customers who say it’s the only soil they trust for their gardens. One reviewer claims: “I have already new leaves on some of my crops with just a week of repotting.” However, long-time users do say that supplementation may be needed after a month or so.

3. BEST ORGANIC: Purple Cow Organics IndiCanja Organic Compost Soil

Cut back your carbon footprint and grow some premium flower with this plant-based, no-water formula.

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Product Specs 

• Weight: This bag weighs 15 pounds.
• Type: This type of soil is humus.
• NPK: The NPK ratio is 0.8:0.8:0.8.

You don’t need to be a hippie to appreciate the appeal of this sustainable, earth-friendly potting soil. Purple Cow’s IndiCanja Organic Compost Soil is made entirely from plant-based ingredients, so it’s rich in nutrients and ready to use right out of the bag.

It’s a cannabis-friendly mix of minerals, compost, and organic matter not only increases your plant’s health, yield, root mass, and biodiversity but also ups their natural water uptake. The result is some seriously dank buds—and a reduced carbon footprint to boot.

Some reviewers complained of gnats, but that may be more of an overwatering problem than anything else. If you’re looking for an eco-friendly option that doesn’t skimp on quality, this is the soil for you.

4. BEST FOR MIXING: Roots Organics Formula 707

If you love to get your hands dirty, this organic potting mix is perfect for customizing your own soil recipe.

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Product Specs 

• Weight: This bag weighs about three pounds.
• Type: This mix is made of peat moss and potting.
• NPK: The NPK is unlisted.

Is there anything more fun than playing in the dirt? We think not. If you’re into creating your own cannabis-friendly formulas, then you’ll want to pick up a bag (or three) of Roots Organics’ Formula 707.

Everything about this mix is top-notch and ready for DIY, from the fewer nutrients to the soil bags that double as pots. And while you’re free to “control your own destiny” with this organic growing media, the included mycorrhizal fungi will help give your roots a boost by increasing their biomass and helping them better resist the stress of container growing.

Be warned: bugs are a common complaint, but sterilizing the soil prior to planting should kill off any unwanted critters.

5. BEST FOR FIRST-TIMERS: FoxFarm Happy Frog Potting Soil

Newbies and old-timers alike will appreciate the convenience of this nutrient-rich potting soil.

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Product Specs 

• Weight: This bag weighs 45 pounds.
• Type: This type of soil is humus.
• NPK: The NPK needs to be clarified.

Happy Frog is a beloved classic for a reason: it’s reliable, easy to use, and boasts a lengthy list of satisfied customers. This potting soil is perfect for first-timers (or those who don’t want to mess with mixing their own formulas) and is enhanced with mycorrhizal fungi and soil microbes.
Already pH adjusted for maximum nutrient uptake, you can toss this soil straight into the pot without any extra prep work. Just add water and plants, and you’re good to go. Reviewers love how well it holds water, how much soil you get per bag, and how gorgeous their buds look after using it. Just ask one reviewer who said it “will give your flowers a boost they need to be absolutely beautiful!”

 

My verdict

All the options on this list are stellar, but there are two clear winners: Super Soil Autoflower Concentrate and FoxFarm Ocean Forest Potting Soil. Both bags are rich in nutrients, easy to use, and come in large sizes— everything you need to grow healthy, vibrant cannabis plants.

Our recommendations

How we chose the best soil for cannabis

Dirt is dirt, right? Not quite. When it comes to cannabis, the type of soil you use can make a big difference in the health and yield of your plants. 

To help you find the best soil possible, we looked at nutrient content, ease of use—the less DIY-ing, the better—and bag size. After all, nobody likes running to the store for more soil every other week. 

We also considered customer reviews, paying close attention to those that mentioned plant health. While every bag of soil is vulnerable to bugs and smells, we only considered those that had the fewest complaints in these areas. 

What kind of grower this product is for

Despite its intimidating nature, anyone can grow cannabis. Finding the right soil is really just a matter of understanding your strains’ needs and deciding how much extra mixing and measuring you’re willing to do. Because there’s a huge selection of ready-to-use soils on the market, we recommend starting with one of those if you’re new to the marijuana-growing game.

What to know before you buy potting soil for your marijuana plants

Growing cannabis is kinda like baking a cake—you need the perfect mix of ingredients to create something magical. And soil is the foundation of a great grow.

The best soil for cannabis will have the perfect mix of nutrients, pH balance, and composition to support your plants through every stage of growth—and there are multiple materials you can use to achieve that perfect mix.

Types of soil for growing weed

You can’t just slap any ol’ dirt in a pot and expect your cannabis to thrive. The type of soil you use can make or break your crop, so it’s important to do your research and find the perfect mix for your plants. Below are some of the most popular types of soil for growing weed.

Loam

By far the most highly recommended type of soil for cannabis, loam is a mix of sand, silt, humus, and clay. This combination is uber fertile and provides plants with the drainage they need to prevent root rot while also holding enough moisture and nutrients to support growth. You can never go wrong choosing loam.

Humus

This organic ingredient of outdoor soil is what you’ll find at your neighborhood gardening shop. While some people refer to it as compost, it’s actually not quite there. Compost is the final product of the decomposition process, while humus is just one organic matter added into compost. It’s a great option, but just know that even though many humus soils claim to be bug-free, you can usually find at least one or two critters.

Moss

As it turns out, the layer of leaves, twigs, and other decomposing organic matter that you find on the ground in forests are actually great for growing weed. 

Moss—particularly sphagnum and peat moss—is dense yet airy and has an uncanny ability to absorb and retain nutrients. It also helps to keep the soil moist, making it an ideal growing medium for cannabis.

pH

Marijuana plants are very particular about the levels of acidity and alkalinity in their soil. Striking the perfect pH balance is essential to ensuring a healthy, robust crop. The general scale runs from 0 (very acidic) to 14 (very alkaline). Guess where your plant’s preferred pH range falls? Right in the middle, at 7.

To achieve the ideal middle-of-the-road pH level, look for soil that has pH 7 labeled clearly on its bag. You might also want to grab a cheap pH monitor to check the level periodically throughout the grow cycle so you can make adjustments as needed.

Nutrients

If you want to be the ultimate cannabis plant parent, commit the following acronym to memory: NPK. It stands for nitrogen, phosphorus, and potassium.; A.K.A., the vital nutrients your indoor nursery needs to survive and thrive.

While you can always use a fertilizer that contains all ingredients, it’s much easier to cut out the additional step and find soil that already has them mixed in. Most high-quality potting soils will have NPK values listed on the front of the bag so you can make an informed decision. The best combinations are 20:20:20 and 12:12:12.

Composition

You want the composition of your soil to be a bit like Goldilocks porridge—not too moist, not too dry, but just right. Anything too wet will block airflow and lead to root rot. Too dry, and your plant’s growth will be stunted. 

There will be a label on the bag that states whether the soil is wet or dry, but it’s always a good idea to test it out for yourself. The perfect mix will have a crumbly texture that is loose but feels slightly heavy. You can mix the different soil types above to get that perfect consistency. 

Tips for mixing soil for cannabis

As nice as it would be, there is no perfect mix of soil for cannabis. Different strains have different nutrient requirements. So a great deal of your plants’ success depends on how well you understand their individual needs.

Most strains fall into three categories: needing high levels, normal levels, and low levels of nutrients. 

• If your strain falls into the high category, you’d do best with soil that had a 20:20:20 NPK ratio. 
• Normal levels require a little fewer nutrients with an NPK ratio of 10:10:10. 
• And, of course, low levels require much less. A 5:5:5 NPK ratio is plenty. 

If you really want to get geeky with your grow, follow these other tips for mixing soil:

• Really get to know the specific needs of the strains you’re using so you can choose a soil mixture that will support them throughout the entire grow cycle.
• Mix different soil types together to create a custom blend that meets the specific needs of your plants.
• Never bring natural outdoor soil into any indoor growing operation because bugs and other nasty pets can totally comprise your crops.

FAQs

Growing cannabis is by no means an easy hobby. It takes time, patience, and a fair bit of knowledge to get it right. But if you put in the effort, you will be rewarded with some of the best herb around. Below are some answers to common questions about cannabis soil to help you get started.

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