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best potting soil for marijuana seeds

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.

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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!

Best Soil for Growing Weed [The Grower’s Guide]

Whether you want to call it dirt or a growth medium, soil is a crucial component for growing marijuana. Choosing the best soil for your weed is arguably the most critical decision you’ll make when growing cannabis at home. Getting it right is likely the difference between a bountiful harvest and utter failure.

The apparent simplicity of picking soil often fools newcomers, and they frequently make mistakes that cost them their harvest. The truth is, you have to make a lot of considerations. For example, the soil you use for indoor growing is not the same one you’ll need for an outdoor grow. Then there is the small matter of things like pH, drainage, and a host of other criteria.

There are a large number of soil brands available, which is both good and bad news. You get a lot of options. However, with so many choices, how do you determine the best soil for growing your marijuana? The key is to analyze your situation, and our guide will help do the rest.

Pros & Cons of Growing Cannabis in Soil

Ultimately, you can choose between soil or a hydroponic system if you wish to grow weed at home. A hydroponic system is potentially extremely effective, but it is also expensive. Generally speaking, those cultivating their cannabis for the first time should choose soil. The roots of your plants will extend deep into the earth as they look for nutrients and water.

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That’s why indoor systems, which have a lack of space, need to create smaller root systems for marijuana. Regardless of the root system you choose, make sure the temperature in the growing area stays around 68 degrees Fahrenheit.

Of course, ample water and oxygen in the soil is a must.

Irrigation in soil is easier than with hydroponic systems, as is fertilization. With so much information gathered from thousands of years of growing, you can quickly become a soil expert as long as you read the right articles!

On the downside, soil requires a ton of space, and it is cumbersome. You’re also more likely to have issues with pests than with a hydroponic system.

Choosing the Right Cannabis Soil Container Size

The size of the containers you choose will dictate the size of the marijuana plant’s root system. The more space the roots have, the faster they grow. You can expect problems to arise when the roots outgrow your container, so choose wisely! There is no need to go beyond a 10 x 10 x 10 cm container while your plants are still seedlings.

Once it reaches a height of 25cm, transplant the plant(s) to a container that is at least double the size of the first one. Once your plant hits the lofty heights of 80cm, move it to at least a 12-liter container. Once your plant hits a meter in height, you’ll need an even bigger box. This process continues until harvest.

Watering Your Soil

The soil type and growing environment determine the way you water the soil. Hot climates need more water, and colder climates need less.

When you water the plant, it moves essential nutrients and minerals to the roots. Then, they travel to the rest of the plant. Water cools overheated plants down and is a critical ingredient for photosynthesis. The best advice we can give is to water the soil until it is moist, but not wet to the touch. Overwatering aids the growth of harmful fungi, which can result in root disease, so exercise caution!

Quality Soil for Cannabis

Natural soil comes in four varieties: sandy, silt, loam, and clay. You are in for a nasty surprise if you think that soil is just one ‘type.’

Many soils will have a combination of at least two of the four types. Therefore, you can have sandy/silty, loamy/clay, silty/clay, and so on. If that isn’t confusing enough, there are different ratios of every soil type. It is an important consideration, however, because each one has its pros and cons.

Sandy Soils

Sandy soil is known for its large granular size and has a low pH. The issue with this type of soil is that it dries quickly and often experiences difficulties in moisture absorption. The nutrients also get washed away, and nitrogen, in particular, is lost rapidly from sandy soil.

On the plus side, sandy soil is easy to prepare for cultivation, offers good drainage, and contains high oxygen levels. It is one of the best options for growing weed indoors.

Silt Soils

This soil type consists of minerals such as quartz and fine organic particles. Although they hold moisture, silt soils have decent drainage and are one of the easiest to work with when wet. Also, silt soils are among the most fertile, which gives you a chance of a decent-sized harvest. With frequent irrigation, you can extend the length of the growing season. Silt soil is one of the best soil types for seedlings.

Loam Soils

Loam soil is a combination of sand, silt, and clay, typically in a 40/40/20 ratio. It has at least 20% organic compounds and can vary from being easy to work with to incredibly complex. To identify a loam soil, squeeze it. It should form a loose ball that quickly threatens to break apart.

This is a prevalent marijuana potting soil and has an almost neutral pH. It offers excellent drainage and water retention, contains high oxygen levels, and is naturally fertile. However, it is by far the most expensive option.

Clay Soils

This type of soil is among the best organic options for cannabis. Clays consist of fine crystalline particles created via chemical reactions amongst minerals or other natural resources. You can mold or shape clay soil, but it is hard to work with and drains poorly.

If you try to use this kind of soil, expect to have difficulty in getting the plant’s roots to penetrate the surface. Clay soil has a high pH. While it stabilizes plants, the soil is heavy and requires a lot of effort overall.

What Does Loam Soil Look Like?

Loam is, without doubt, the favorite weed soil of growers. It makes the best soil for potted plants and is probably the best soil for plants in general. It contains the right balance of all three soil types (clay, silt, and sand) along with humus. This combination ensures that loam has high calcium levels, but it also has a relatively high pH.

Loam has a dark color and is soft, dry, and crumbly when you hold it. Although it offers a tight hold on plant food and water, it drains exceptionally well. The air can freely move between the particles down to the marijuana plant’s roots.

How to Make Loam Soil

Loam soil is a combination of the three main soil types. However, don’t think you can create loam soil by adding clay soil to silt, or vice versa. If you try to add sand to clay, for instance, you’ll end up with a cement-like texture. In reality, creating loam soil for your plant is not a straightforward or quick process.

It is, however, the best soil for cannabis, which means it is worth the time and effort that you have to put in. No matter what type of soil you have, creating loam involves adding organic matter to it each year. The decomposing plant material creates the excellent drainage conditions your weed needs.

The trouble with organic matter is that it gets depleted rapidly. This means you have to amend it on a season by season basis.

The amount of work you must do depends on the balance of your existing soil. For instance, if it has high amounts of clay or sand, you’ll have to add large amounts of organic matter several times a year. You can add a two-inch layer of organic matter onto the surface of the garden. Then, you should work it into the first couple of inches of soil.

Buy Only the Right Soil for Your Cannabis Plants

It is normal to go to your local garden store full of enthusiasm. That is until you are knocked back by the enormous number of options. First of all, please note that buying it in bulk could be a mistake. There are no certifications or standards attached to soil quality. Believe it or not, some of these sellers provide you with soil from construction sites. They could even sell soil excavated from basements!

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When buying soil for weed, make sure you understand the basics of good cannabis soil. If you want your plants to offer lots of cannabinoids and trichomes, you have to pay attention to several variables. including:

  • Drainage, texture, and water retention
  • Nutrients
  • pH

Drainage, Texture & Water Retention

The texture, drainage ability, and water holding ability are arguably the most critical aspects of marijuana soil. Your plant will not produce a good yield if it doesn’t have the right mixture of water and oxygen in the roots 24/7. If there is too much water, the roots won’t get enough oxygen. If there isn’t enough water, the roots can dry out quickly and become damaged.

High-quality marijuana soil should have:

  • A rich and dark color
  • Loose texture
  • Excellent drainage; in other words, it should not make a pool on top of the soil for more than a few seconds
  • The ability to retain water without becoming muddy

It is unlikely that your cannabis soil will have the ideal drainage, texture, and water retaining abilities. Fortunately, there are a host of amendments available to alter the drainage, texture, and water-retaining capacity of your soil. Here are four of the most popular:

Coco Coir

This is made from coconut husks and manages to improve water retention without causing the soil to become heavy. When you use coco coir, the roots of your plant should develop quicker, and you’re less likely to overwater. You can grow your marijuana in pure coco coir. However, a maximum of 30% is best for a productive soil amendment.


This enhances water retention and causes your soil to become ‘lighter.’ It works particularly well with Perlite.


This is probably the most commonly purchased amendment and is ideal for practically any soil mix. It consists of airy ‘rocks’ known for their white hue. Perlite looks a bit like popcorn and improves drainage while adding oxygen. Use 10-20% to improve water retention. You can go as high as 40%, but you risk leaching nutrients faster. If you use Perlite and Vermiculite, don’t go above 50% for the two combined.

Worm Castings

Yes, we are talking about worm poop! Once you get past the initial horror, you’ll find that your marijuana plants adore worm castings. They improve water retention, drainage, and texture. Their natural nutrients are quickly broken down. Worm castings typically include useful microorganisms since they go through the digestive systems of worms. Keep the level of worm castings down to around 30%.


As long as you choose correctly, your cannabis soil should already have a vast array of nutrients because it consists of organic material. One mistake is to try and add organic material such as animal manure and rotting vegetables directly to the plants as fertilizers. You must break down the content first if you want your marijuana plants’ roots to absorb the nutrients.

Indoor growers need to find soil with a lot of nutrients.

This is because they don’t benefit from nature in the same way as outdoor growers. Use heat to sterilize the soil and add nutrient-rich potting soil mix. You can make it yourself, but newbies should purchase it from the garden store. Water the soil correctly. Also, keep it in a room with a temperature of 68 degrees Fahrenheit and test the pH every so often.

In case you weren’t aware, pH means ‘potential of hydrogen.’ It is a chemical scale that determines a substance’s alkalinity or acidity. The range goes from 0-14. A pH of 7.0 is neutral (pure water is 7.0, for example). Everything from 0-6.9 is acidic, while everything from 7.1 to 14 is alkaline.

Battery acid and hydrochloric acid have a pH of 0, while liquid drain clearing fluid has a pH of 14. Ideally, your cannabis soil is slightly acidic. Most experts believe that the ideal pH is 6.0. However, you are on solid ground if your soil’s pH is between 5.8 and 6.3. Your crop will survive outside of this range, but the yields are likely much smaller. If you stray too far from the 5.8-6.3 range, the plants will die.

Soils for Cannabis: Recommended by

If you are a beginner grower, you must purchase your soil from a garden store. Did you know that the vast majority of expert growers also buy their soil? A handy tip when talking with a store employee is to ask about the right kind of soil for tomatoes. It is an excellent option if you feel uncomfortable disclosing your desire to grow weed!

At, we took the liberty of recommending a few store-bought soils for your cannabis plants. Please note that these are NOT for seedlings, as they contain too many nutrients. These are soils designed to help your plant thrive once it reaches the vegetative stage. Otherwise, you need to look at potting soil brands when your plant is still a seedling.

Before we continue with the best soil brands for growing cannabis, let’s look at general guidelines for indoor and outdoor soil.

Best Soil for Indoor Plants

Overall, you can’t go wrong with an organic super soil and fertilizer mix. The super soil offers the ideal blend of nitrogen, phosphorus, carbon, and a myriad of other nutrients. You can make them yourself, but once again, we recommend investing in store-bought pot soil.

Best Soil for Growing Weed Outdoors

When growing weed outdoors, make sure you use soil that feels fluffy in your hands. It needs to possess a reasonable amount of nutrients, and good drainage is essential. Compost and store-bought fertilizer can form a fertile and productive base. Crucial nutrients include Nitrogen, Potassium, and Phosphorus.

Best Cannabis Soil Brands

Best Organic Soil – Roots Organics

This organic blend is designed to enable a higher water-holding capacity. It includes ingredients such as bat guano, kelp meal, and fish & crab meal. It is suitable for marijuana plants that are beyond the seedling stage. We love the ready-to-use pot because it enables you to transfer your plants immediately.

Best for Seedlings – Espoma

This is a great option if you want to nurture your crop from seedling through to harvesting. This Espoma soil contains excellent nutrition for early-stage growth. You will need to begin with small pots, before transferring your growing plants later. It contains peat moss, perlite, and peat humus – not to mention a hose of nutrients that aid strong root growth.

Best of the Rest – FoxFarm FX14047

The Fox Farm company has over three decades of experience in the industry. It is a well-renowned maker of cannabis soil in the United States. Its FX14047 soil mix contains a unique blend of mycorrhizal fungi, and much more. It helps increase root development rapidly. When you use FX14047, your plants will develop a strong structure and experience rapid vegetative growth.

It is a lightly textured and well-aerated soil. Its pH is adjusted to ensure your plants feed more aggressively. You get two cubic feet of organic soil, and it is ready to use out of the bag.