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The Definitive Guide To The Best Soils For Cannabis

Dirt, soil, growth medium—call it what you like, it’s an essential component for any cannabis growth operation. In fact, choosing the best soil for cannabis is one of the most important decisions you’ll make in the process of growing your own pot plants.

It’s so important that it can mean the difference between a successful harvest and complete failure. Which would you rather have: bountiful buds or a plant so unhealthy you can’t even compost it next year? That’s what using the right soil can do. So, yeah, a lot’s riding on your choice.

But what is the best soil for cannabis? What ’s the best pH? What if you’re growing outdoors? What if you’re growing indoors? The questions literally go on and on and on. But never fear, my friend. The experts at Honest Marijuana are here to help!

We’ve been growing some of the finest cannabis in the world for almost a decade. And we’ve been doing so the way mother nature intended: in 100-percent all-organic soil, without pesticides, chemicals, or growth regulators.

We’ve learned a lot in those years, and we want to pass on our knowledge to you. To do that, we’ve put together the definitive guide to the best soils for cannabis so you don’t have to worry about your head exploding while trying to sift through all the information. Let’s start our dirt-y adventure by discussing the basics of good cannabis soil.

The Basics Of Good Cannabis Soil

Cannabis is often considered a weed (hence the name) because the plant can pop up and thrive in diverse conditions. But that doesn’t mean you should just scatter your sensimilla seeds in the backyard and hope for the best. This isn’t Jack & The Beanstalk, bro.

Yes, your cannabis weed can grow in a wide range of soils, but to truly flourish—to produce lots of trichomes , THC, and other cannabinoids—it needs just the right balance of variables in the soil. These variables include:

  • Proper drainage
  • Good water retention (sounds counterintuitive to the first variable, but it’s not)
  • Correct nitrogen to phosphorus ratio (this is done in the composting phase)
  • The right balance of fungus to bacteria (a slight skew to the fungal side of the spectrum is okay because cannabis prefers slightly acidic soil)
  • Soil pH of 6

Let’s discuss that last bullet point—pH—in a bit more detail.

Best Soil pH for Cannabis

pH (yes, the ‘p’ should be lowercase) stands for potential of hydrogen. It’s a chemical scale used to specify the acidity or basicity (alkalinity) of a substance ( usually a liquid).

For example, liquid drain cleaner and bleach (14 and 13.5 respectively ) are both very basic. Battery acid and hydrochloric acid (both 0 pH) are both very acidic. Between those two extremes lie more common items, like:

  • Baking soda (9.5)
  • Sea water (8)
  • Pure water (7) (this is considered neutral on the scale)
  • Coffee (5)
  • Lemon juice (2)

Keep in mind that numbers above 7 are basic (alkali), while numbers below 7 are acidic.

So because soil contains water, it also has a pH. As mentioned in the section above, cannabis likes its soil slightly acidic. The ideal number is 6, but it can also flourish on either side at 5.8 and 6.3.

If your soil strays slightly higher than 6.3 or slightly lower than 5.8, the plant will still survive but it won’t produce as well . Keep your soil around 6 for the best crop.

To do this, you’ll need to purchase a soil pH tester. Sorry, there’s just no way around it. Sticking your finger in the dirt and then in your mouth is not an accurate test of pH.

The one consolation is that these testers aren’t very expensive. You can pick up a perfectly good soil pH tester for around ten bucks at Walmart or Amazon.

Of course, there are plenty of more expensive models that do everything but wash your dishes (some even do that), but there’s no reason to drop a c-note for this kind of functionality. Your basic, run-of-the-mill pH tester will do just fine.

Best Soil For Outdoor Cannabis

Natural soil (by that we mean soil found outside) comes in three main types:

  • Sandy
  • Loamy
  • Clay

But not all soil is just one type. They can be sandy/loamy, loamy/clay, sandy/clay, or any other combination of the three. To make things even more confusing, there can be different ratios of each soil type. And each soil type has its own benefits and drawbacks.

If you absolutely must grow your cannabis outside in the ground, we suggest digging a three-foot-wide, three-foot-deep hole and filling it with the organic super soil we show you how to make below. This will give your cannabis plant the proper drainage, water retention, and amount of nutrients to help it grow tall and strong.

You also have the option of growing your cannabis plants outside in a pot. Just fill a three- or five-gallon pot (or bucket) with the organic super soil we describe below and plant your seed. You will have to monitor the temperature, humidity, rainfall, amount of sun, and pests if you’re growing your cannabis plant outdoors.

The nice thing about growing your cannabis in a bucket or pot is that it’s portable. Weather not behaving? Take the plant inside. Pests attacking the leaves? Take the plant inside.

The only downside to doing this is that you’ll have to spend some money to control the light, air movement, and humidity. But once you’ve got the gear, you won’t be at the mercy of the elements (which can be unpredictable and cruel) and you can give your growing plant exactly what it needs to flourish.

Best Soil For Indoor Cannabis

The best soil for indoor cannabis growing is organic super soil and 420 fertilizer mix . We show you how to make these two indispensable items in the last two sections of this article.

The organic super soil, in particular, gives you the right balance of carbon, nitrogen, phosphorus, and a whole host of other nutrients to ensure that your cannabis plant gets exactly what it needs during every stage of growth . Add to that the 420 fertilizer (you can make yourself) and you’ve got a great recipe for growing tall plants with plenty of buds and lots of cannabinoids.

Of course, you can choose to purchase soil rather than make it yourself. This is particularly good for those who don’t have a lot of space outside to set up a compost pile. We’ll talk about the best bagged soils in the next three sections.

Best Potting Soil For Cannabis

If you must buy a bagged soil and your local garden store doesn’t have a lot of choices, anything with the words “organic potting soil” or “organic potting mix” will work. It’s not the ideal, but it will do in a pinch.

Your best bet is one of the organic soils listed in the next section or the homemade super soil we talk about at the end of this article.

One thing you want to look for when buying potting soil for cannabis is that it does NOT contain any slow-release chemical nutrients. If your potting soil contains these time-released chemicals, it could give your marijuana plant the wrong nutrients at the wrong time. That could spell disaster for your cannabis crop.

If your garden store has more of a variety, look for one of the following brands.

Best Organic Soil For Cannabis

These organic soils have been tried and tested as cannabis-friendly products. You’re still better off producing your own organic super soil and 420 fertilizer, but these can work in their absence. Visit any marijuana-grow chatroom and you’re likely to see these products mentioned more than once.

Black Gold Soil For Cannabis

For years, Black Gold was the go-to potting soil for the discerning cannasseur. Black Gold also makes other additives such as peat moss, earthworm castings, perlite, compost, and vermiculite you can use to supplement the lack of necessary cannabis nutrients.

Fox Farm Soil For Cannabis

Fox Farm is another bagged soil used by cannabis growers. The Ocean Forest mix is particularly effective at giving your cannabis plants just the right soil conditions to grow their best.

To give you an idea of what’s in the mix, here’s a breakdown of the Ocean Forest ingredients:

  • Sea-going fish emulsion
  • Crab meal
  • Shrimp meal
  • Composted forest humus
  • Sphagnum peat moss
  • Worm castings
  • Oyster shell
  • Sandy loam
  • Bat guano
  • Granite dust
  • Norwegian kelp

Doesn’t sound appetizing to me, but cannabis plants just love it.

Best Soil For Autoflowering Cannabis

The amount of light a plant gets during the day is responsible for making that plant flower . These are called photoperiod plants. Cannabis plants grown outdoors need between 12 and 15 hours of light per day. That usually doesn’t happen until later in the summer.

Of course, that variable can be controlled by growing your cannabis indoors (where the plant needs closer to 18 hours of fluorescent light).

But some cannabis plants are what’s known as autoflowering. That means the plant isn’t dependant on the amount of light it receives to trigger its flowering stage. Instead, autoflowering cannabis plants will transition to the flowering stage when the plant reaches a certain phase of development.

Autoflowering cannabis prefers a more light, airy soil with a relatively low level of nutrients. That makes many of the soils and mixes discussed above less than ideal. That doesn’t mean you can’t use “normal” soil. It just means that you’ll get a better result with a lighter soil.

Try mixing your own autoflowering soil with the following recipe:

  • 3 parts compost
  • 3 parts peat moss
  • 2 parts wet perlite
  • 1 part wet vermiculite

For those of you using regular, photoperiod marijuana seeds, the next two sections will be your definitive guide to making the best soil for cannabis.

How To Make Your Own Organic Super Soil

To make your own organic super soil, you need to be able to control things like temperature, airflow, and carbon-to-nitrogen ratio. Check out Honest Marijuana’s How To Grow Marijuana: The Ultimate Organic Guide for advice on these variables. Once you’ve got all that straight, here’s a step-by-step guide to making your own soil.

  1. Mark out a three-by-three square on the ground.
  2. Lay down a four-inch layer of carbon material like dry leaves or straw so that it covers that three-by-three square.
  3. Add a four-inch layer of nitrogen material like livestock manure or coffee grounds.
  4. Top that with a half-inch layer of blood or bone meal.
  5. Repeat the first three steps—layer by layer—until your pile is three feet high.
  6. Leave the pile to decompose.
  7. Turn the pile at least once a week, but not more than every three days.
  8. The composting process is complete when the soil is soft, crumbly, dark black, and smells sweet.

You can use that soil for planting your cannabis seeds and for mixing your own 420 fertilizer.

How To Use That Soil To Make 420 Fertilizer

This 420 fertilizer can be used throughout the grow process to keep your cannabis plant happy and healthy. Here’s the recipe.

  1. Lay down a large tarp or purchase a plastic kiddy pool. We like the kiddy pool because it makes mixing and corralling the fertilizer easier.
  2. Spread a one-inch layer of your organic super soil.
  3. Mix in a scoop each of coco fiber and mycorrhizae .
  4. Toss in:
    a. 0.75 kilograms of rock phosphate
    b. ⅛ cup of Epsom salts
    c. ¼ cup of Azomite (trace elements)
    d. ½ cup of sweet lime (dolomite)
    e. 1 tablespoon of powdered humic acid
  5. Add another one-inch layer of super soil
  6. Spread on 1 kilogram of bat guano.
  7. Add another one-inch layer of super soil.
  8. Spread on 1 kilogram of blood meal.
  9. Add another one-inch layer of super soil.
  10. Spread on 1 kilogram of steamed bone meal.
  11. Add another one-inch layer of super soil.
  12. Mix everything together with a shovel.
  13. Fill a garbage can (or garbage cans) about ¾ full with this new mixture.
  14. Pour 2.5 gallons of water in each can.
  15. Leave this to steep in the sun for one month.

After thirty days, you can use this liquid to fertilize your growing pot plants.

Some Tips We’ve Learned Along The Way

Here are a few other essential tips we’ve learned along the way to make creating the best soil for cannabis just a bit easier.

  1. Collect all the ingredients before you begin.
  2. Take it slow. There’s no need to rush.
  3. Start recording everything you do (in regard to the soil) so you can figure out how to improve the process.
  4. Learn how to use and read a pH tester.
  5. Get friendly (not too friendly!) with the folks at your local garden center or greenhouse. They can provide a wealth of information about all things soil.

After that, just dive in and get your hands dirty. That’s the only way you’re going to learn. Happy growing!

Thinking about growing your own cannabis? Not sure what soil to use? The experts at Honest Marijuana tell you everything you need to know to grow the best plants.

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!