Best Soil For Cannabis Seeds

The best soil for cannabis plants depends on a variety of factors. Learn how to find or make the best soil for growing marijuana! Soil is the root of all plant life. Plenty of high-quality cannabis soil preparations are now available for growers with all different cultivation styles Soil is the medium of choice for most cannabis cultivators. Here is what you need to know to get the most out of your soil grow!

What is the best soil for cannabis growing?

If you’ve thought about growing, you’ve probably already thought about the best soil for cannabis.

You likely didn’t give it that much thought, though, because who takes time to think about soil?

Well, the soil that you grow your marijuana in is very important, so if you want to grow the best weed possible, you should pay some attention to it.

This guide will cover everything you need to know about the common growing medium.

How to choose the best soil for marijuana plants:

The basics of using soil for marijuana grows

Plants typically need three things to survive: water, light, and soil.

Soil may seem obvious, but nowadays, with soil alternatives and hydroponic growing, even that is optional.

However, for most growers, especially those who are new to growing marijuana, growing in soil is the best option.

Soil growing (instead of growing in nutrient-infused water) is one of the easiest and most familiar methods of growing.

Plus, attempting to grow hydroponically the first time you are growing marijuana is almost guaranteed to be a recipe for disaster.

Soil is simply the natural way to grow, but it is still important to start with a good quality soil.

After all, it provides the plant’s nutrients and helps the plant form stable roots.

High-quality soil is especially important for outdoor plants who could face potentially harsh winds and other environmental conditions.

Why grow marijuana in soil?

Great soil can help your plants thrive, so it is essential to first understand what soil is.

It is definitely more than dirt.

Advantages of using soil

The soil is the most natural medium for growing almost all kinds of plants. It means that most people already are familiar with or have experience in doing it.

In effect, it is easier and less stressful to use than other modes of planting, which requires a learning curve.

Another advantage is its simplicity in making it work. Just watering the soil is enough for most plants to grow.

Also, the supplies needed are few compared to using other costlier mediums.

Natural soils are made up of mineral particles, air, organic matter, water and biological organisms.

Disadvantages of Using Soil

Since soil is an organic material, it is natural for bugs to live in it.

Therefore, the plants are more prone to suffer from pest infestations.

There is also the issue of slower growth.

In contrast, marijuana grown using hydroponics enjoys explosive growth due to faster and more efficient nutrient absorption.

Nearly 25% of soil is air that exists in a gaseous phase –not quite liquid or solid.

Water

Water is known as soil solution, a liquid made of water, and ions from dissolved salts, and chemicals.

These ions are unable to attach to minerals in the soil.

Water also makes up nearly 25% of soil. The mineral particles in soil consist of sand, clay, and silt.

These inorganic particles can significantly impact a soil’s quality.

These tiny fragments of rocks and hard minerals (such as quartz) do not carry any nutrients, meaning large amounts of it in your soil is a bad thing.

Soil with lots of sand is arid;

however, small to moderate amounts can improve drainage and aeration as well as increase tilling quality.

This mixture of sand and minerals has some nutrients, but not many.

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It is is beneficial for soil, as it can include the important nutrients of K, Ca, Mg and Fe- making soil fertile.

Clay is aluminum-silicate and has negatively charged ions that attract these nutrients to it.

However, if there is too much clay, it will be hard to till the soil, and there will also be poor drainage.

Soil also includes a variety of organic matter and substances such as:

  • Decomposing plant and animal particles
  • Organisms and microorganisms living in the soil
  • Substances produced by roots and microorganisms

These exist in smaller amounts, typically around 5%. Although there isn’t much organic matter in soil, its presence highly influences its quality and the eventual yield of your plants.

The particles and substances are also known as humus, whereas organisms may include earthworms and other beneficial creatures.

How to recognize the best soil for cannabis

Now that you understand what soil is, it is much easier to recognize good soil when you see it.

Marijuana soil has some specific requirements, so unless you are buying soil that is specifically designed for cannabis, you’ll want to learn to pay attention to certain things.

Good soil will have the correct texture, drainage ability and water retention for marijuana. It will look dark and rich, with a loose texture that isn’t muddy.

Good marijuana soil also drains well – you should be able to pour water on it and have it drain out within a few seconds.

The soil should retain enough water for the plant to thrive, as the roots need that water, but it shouldn’t be so much that the roots cannot get enough oxygen either.

This is why both proper drainage and water retention are essential aspects of good soil.

Good soil also has good ingredients. Of course, soils that include some form of organic matter (humus) are great for marijuana because they provide plenty of nutrients.

Some examples of organic matter to look for in a good cannabis soil include:

  • Earthworm castings
  • Bat Guano
  • Blood, fish, or bone meal
  • Kelp
  • Mycorrhizae
  • Perlite
  • Pumice
  • Sandy Loam
  • Dolomite lime

If you purchase soil that has any of these ingredients in it, there’s a good chance it might provide great nutrition for your plants.

You’ll still want to make sure that it has the right nutrients for your plant’s particular stage in its life cycle though.

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Choosing soil for your marijuana plants

With an understanding of what you are looking for, you can now start to select the right soil for your plants.

The first thing to remember is that soil is highly dependent on the stage of life that your plant is in.

While it is still sprouting, it is best to use peat plugs or something similar to that.

These ready-made blocks of soil provide everything that a budding seed needs to make its way into the world.

If you can’t find, (or don’t want to use) peat plugs, an organic potting soil will also work.

Organic soils will not have any added ‘slow-release’ chemicals, something you’ll want to avoid when growing marijuana.

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While potting soils do not have the right type of nutrients to support a growing marijuana plant, they will have enough to support a seedling for its first couple of weeks.

After that point, you’ll want to supplement with nutrients that are specifically designed for marijuana plants – especially once you reach the flowering stage.

Another reason why it is okay to use potting soil (at least at first) is because you’re likely going to end up moving your plants after they are about a month old anyway.

The roots will be too big for their first home, and you should place them in a bigger container or move them outdoors.

That is the perfect time to switch out your soil for something more suitable.

If you used peat plugs, you can simply add the plugs to local dirt or grass mulch to make a suitable soil outdoors.

Not only does this provide a better texture over the natural earth, but it also offers ample room for young roots to move around and increases the nutrient value in the soil.

You can also move your seedlings into either sterilized potting compost or a “living soil.”

If you opt for sterilized soil, it should include some form of amendment (such as perlite), that makes up at least 20% of the soil.

This additive will help increase the amount of air present in the soil, which helps marijuana plants grow faster.

Living soils, on the other hand, are composted soils.

They are useful because they include microorganisms that create an ecosystem similar to the best natural scenario.

The roots directly absorb the nutrients produced from these organisms, and the results are often noticeable in the flavor and scent of the harvest.

Digging into the dankest dirt: the best soil for growing cannabis

Soil is the root of all plant life…because it literally feeds the roots! Sure, you could use hydroponics to grow cannabis, but despite the extra work, hydroponic systems don’t appear to improve cannabis plant growth or potency over soil which is the tried and true growing medium for marijuana. Despite soil’s relative lack of precision compared to hydroponics, it remains the preferred medium for numerous seasoned cannabis cultivators – and is obviously the way nature intended, as cannabis was growing wild long before humans started domesticating it. 1 2

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While many home-growers admire soil, few cultivators can agree on the best soil for growing cannabis. Finding the perfect balance of nutrients, aeration, and water retention can take some time for new and even professional growers to figure out. Not to mention the numerous variables that can influence which soil is ideal, including watering and feeding patterns, types of grow-container used, and even the origin of the variety (or strain) being grown. Thankfully, plenty of high-quality cannabis soil preparations are now available for growers with all different cultivation styles.

Ocean Forest Potting Soil

  • Suitable for potted plants that are moderate to heavy feeders
  • Indoor or outdoor
  • Price: $16.99 – $700+, depending on size

Happy Frog Potting Soil

  • Suitable for potted plants
  • Indoor or outdoor
  • Price: $16.99 – $700+, depending on size

Fox Farm “Bush Doctor” Coco Loco

  • Suitable for potted plants
  • Indoor or outdoor
  • Price: $16.99 – $700+, depending on size

Nature’s Living Soil Autoflower Concentrate

  • Specialized for autoflowering seeds
  • Indoor or outdoor
  • Price: $24, $43, or $68

Purple Cow IndiCanja Organic Living Soil

  • Suitable for potted plants
  • Indoor or outdoor
  • Price: $35.00

Roots Organics Formula 707

  • Suitable for large-container plants
  • Indoor or outdoor
  • Price: ~ $40 – $75

Mother Earth Coco Plus Perlite Mix

  • Suitable for potted plants
  • Indoor or outdoor
  • Price: ~ $75

Ocean Forest Potting Soil

  • Suitable for potted plants that are moderate to heavy feeders
  • Indoor or outdoor
  • Sizes: 12 quart, 2 cubic foot, 27 cubic foot tote, or 55 cubic foot tote
  • Not organic
  • Price: $16.99 – $700+, depending on size
  • contains additions like fish emulsions and crab meal for high nutrient density
  • one of Fox Farm’s most nutrient-dense potting soils
  • full of rich soil amendments like bat guano, crab meal, and fish emulsions

Of Fox Farm’s many best-selling mixes, Ocean Forest usually ranks as the company’s best potting soil for cannabis. This soil formula is more nutrient-dense than Happy Frog, which makes Ocean Forest less reliant on supplemental nutrients. While this could pose problems for young plants, it will help vegetative plants grow to their full potential.

Ocean Forest gets its name from its high concentration of amendments like fish emulsion and crab meal. Ocean Forest’s formula makes nitrogen deficiencies nearly impossible with plenty of earthworm castings and bat guano.

You may need extra nutrients during flowering, but it’s essential to have a light hand when using supplements. Ocean Forest is “hotter” than other potting mixes, so it’s best to cut your recommended feeding schedule by at least half.

If cultivators find Ocean Forest is too hot to handle, they may want to dial it back with milder formulas. For instance, many people enjoy combining Ocean Forest with Happy Frog. Once people learn to use Ocean Forest, they often rave about its performance.

Happy Frog Potting Soil

  • Suitable for potted plants
  • Indoor or outdoor
  • Sizes: 12 quart, 2 cubic foot, 27 cubic foot tote, or 55 cubic foot tote
  • Not organic
  • Price: $16.99 – $700+, depending on size
  • well-balanced
  • mild potting soil ideal for beginners

One of Fox Farm’s “less hot” potting soils, ideal for delicate seedlings.

Excellent soil for beginners who don’t mind adding supplemental nutrients.

Makes it easy to avoid overfeeding and “nutrient burn.”

The Happy Frog Potting Soil is considered one of Fox Farm’s “weaker” soil formulas, but that’s not a criticism! Unlike Ocean Forest, Happy Frog focuses on the beginning stages of growth when plants can’t handle excessive nutrients.

Many cultivators use Happy Frog to give their seedlings a safe space to mature. While Happy Frog has additions like earthworm castings and bat guano, you’ll need to add nutrients as cannabis gets into the vegetative stage.

The allure of Happy Frog is in its simplicity. New growers often have the best time with this soil because they can easily follow their supplemental nutrients’ guide.

Anyone who fears they’ll “overfeed” their cannabis plants should start with a bag of Happy Frog. As you gain more experience with cultivation, consider mixing Happy Frog with more fertilizer-rich formulas during flowering.

Fox Farm “Bush Doctor” Coco Loco

  • Suitable for potted plants
  • Indoor or outdoor
  • Sizes: 12 quart, 2 cubic foot, 27 cubic foot tote, or 55 cubic foot tote
  • Not organic
  • Price: $16.99 – $700+, depending on size
  • rich traces of coco coir provide high-quality pest resistance and water retention
  • high coco coir formula with plenty of nutrient-rich amendments
  • superior water retention and pest resistance

As its name hints, Fox Farm’s Coco Loco formula largely consists of the inert medium coco coir. Unlike plain potting soil, coco coir only has noteworthy traces of potassium. In fact, coco coir is often viewed as a “stepping stone” medium for those transitioning from soil to hydroponics.

While not every grower is a fan of coco coir, it has many excellent features like water retention and pest resistance. Plus, since Fox Farm’s Coco Loco adds ingredients like kelp, bat guano, and earthworm castings, there’s less need to fear nutrient deficiencies.

With Coco Loco, you get the benefits of growing in coco coir without having to significantly adjust your feeding schedule. You may, however, need to tweak your watering schedule, especially if you don’t add perlite which aids in aeration, allowing more oxygen to get to the roots. Coco coir retains moisture more than other mediums, so please resist the urge to overwater!

Nature’s Living Soil Autoflower Concentrate

  • Specialized for autoflowering seeds
  • Indoor or outdoor
  • Sizes: 1 lb., 5 lbs., 10 lbs.
  • Organic
  • Price: $24, $43, or $68
  • rich collection of amendments and microorganisms well-suited for autoflowering plants
  • includes high quality additions ranging from bat guano to bone meal
  • easy to add to regular potting mix for extra root support

Want to create a “super soil” in the shortest amount of time? Try adding Nature’s Living Soil’s Autoflower Concentrate to a generic potting mix.

This well-reviewed soil amendment is so potent you only need to add one pound per five-gallon container. Nature’s Living Soil promises its signature product is “pre-cooked” and contains dozens of beneficial bacteria for autoflowers.

Cultivators are impressed with the wide array of extra compounds like organic earthworm castings, fishbone meal, and kelp. The company also puts beneficial fungi in its formula, which may even give it a slightly “moldy” (but harmless!) appearance.

While Nature’s Living Soil’s Auto Concentrate may seem too hot (or nutrient rich), it’s recommended for all stages of an auto’s life cycle. So, if you want to give your autos a boost, it may be worth your while to mix in this unique concentrate.

Purple Cow IndiCanja Organic Living Soil

  • Suitable for potted plants
  • Indoor or outdoor
  • Sizes: 15 pounds
  • Organic
  • Price: $35.00
  • organic, compost-based “super soil” mix
  • premade “super soil” with dozens of beneficial microorganisms
  • ultra-green organic formula made with compost

Purple Cow may not be as famous as Fox Farm, but it’s gaining attention with fans of “super soil.” This organic soil mix relies on compost to give it higher traces of bioavailable nutrients and bacteria.

According to Purple Cow’s founders, you won’t need any supplemental nutrients when planting your cannabis in this “living soil.” That’s right; just water your soil, and watch your plants grow! While IndiCanja Living Soil may be too intense for seedlings, it should be all you need for mature plants.

Experienced cannabis growers who are curious about “super soils” may want to experiment with Purple Cow’s Living Soil. While IndiCanja may not replace a DIY super soil, it’s far more convenient to try at home.

Roots Organics Formula 707

  • Suitable for large-container plants
  • Indoor or outdoor
  • Sizes: 3, 10, and 20-gallon bags
  • Organic
  • Price: ~ $40 – $75
  • less nutrient-dense formula tailored for advanced growers
  • low-nutrient potting soil that’s ideal for growers who enjoy mixing DIY formulas
  • formula 707’s packaging doubles as a pot

Forget about the ingredients for a second; Roots Organics’ Formula 707 has one of the most fascinating packages. These large container bags could double as your cannabis plant’s pot. Simply cut off the bag’s top and put your plants in. Talk about convenience!

But Formula 707 is way more than its unique container. While this soil mix has fewer nutrients than other formulas, that’s on purpose. Roots Organic intended this formula to accommodate advanced planters who like to make DIY mixes.

You should have some experience adding fertilizers and amendments like perlite before opting for Formula 707. While this may not be optimal for beginners, it’s a worthy choice for cannabis cultivators who crave control.

Mother Earth Coco Plus Perlite Mix

Suitable for potted plants
Indoor or outdoor
Sizes: 27 lbs.
Not organic
Price: ~ $75

  • pre-mixed formula of coco coir and perlite helps balance out drainage and water retention
  • high coco coir formula that gives home-growers optimal control
  • pre-mixed with 30 percent perlite for improved drainage

Like Fox Farm’s Coco Loco, Mother Earth’s Coco Plus Perlite Mix is an excellent choice for coco coir cultivation. This formula has the extra benefit of ~ 30 percent perlite, a useful component of soil which massively improves drainage, water retention and aeration.

While this formula is pretty “bare bones” (literally), that may suit growers who prefer adding macro and micronutrients. Indeed, anyone who struggles with “nutrient burn” may enjoy the superior control Mother Earth’s Coco formula provides.

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Also, using coco formulas allows you to “test the waters” before opting for a hydroponics setup. Since coco coir is essentially an inert medium, it gives cultivators a taste of what hydroponics growing is all about.

What soil type is best for growing cannabis?

A quick tour of online weed forums will reveal many heated debates over the “best” soil for cannabis. While every master breeder has their preferred potting mix, there’s no such thing as the “best soil for growing weed.”

There are, however, some traits that all of the best soil mixes for cannabis share. Home-growers should consider key features such as:

What’s the ideal cannabis soil texture?

In terms of soil texture, cannabis prefers the “golden mean.” What we mean is that marijuana likes soil that has a fair balance of aeration and cohesion. Indeed, most cannabis forums describe the optimal soil texture as “loamy.”

Technically, “loam” combines three soil varieties: clay, sand, and silt. While you could use sand or silt on their own, they tend to be too extreme for optimal cannabis growth.

Sand is great for drainage, but poor at water retention. Silt is just the opposite. So, by merging these soils with water-retaining clay, loam offers an ideal balance for maturing marijuana plants.

It is common for cannabis growers to combine mediums such as coco coir or peat with additions such as perlite, lime, and organic matter (e.g. compost) to recreate the beneficial properties of loamy soil. 3 4

What about nutrient levels?

Cannabis plants require significant nutrients (minerals) to support their rapid growth during their one-season life cycle, and this is why they thrive in highly fertile soils. Generally the main minerals affecting cannabis plant growth are nitrogen (N), phosphorus (P) and potassium (K), but other many macro and micronutrients are also important to plant health. 5 6

Thankfully, cannabis can handle a wide range of nutrient levels without serious negative effects on plant growth and a major benefit of using soil is that it has greater buffer capacity over hydroponics.This means it’s less likely you’ll over- or under-feed your weed versus hydroponics. 7

Cannabis plants require different nutrient compositions at each stage of plant growth, i.e., propagation, vegetative and flowering. In other words, baby plants don’t need the same nutrition as teenagers do, and that too is different from what mature plants need to thrive.

Cultivators should evaluate how many fertilizers are in their soil mix and should also avoid time-released nutrients, as these can seriously disrupt a growing operation.

Generally, the more nutrients there are, the better drainage you need for your plants. While you want your plants to absorb nutrients, you also want to make sure they’re not getting overburdened with a build up of nutrients. Some growers “flush” out excess nutrient minerals during the final two weeks of flowering. 8

It’s common for new cultivators to overfeed their plants, especially when using soil. To avoid this common temptation, novice gardeners should start with soil mixes with minimal fertilizers.

What’s the perfect pH for cannabis soil?

Evaluating a soil’s pH is just as significant as checking out its texture. Cannabis roots cannot absorb nutrients if the pH ratios are out of whack.

While the optimal soil pH for cannabis has not yet been studied in the scientific literature, the common ranges of pH used in the cannabis industry are 5.8 – 6.2 for hydroponics, and 6.8 – 7.2 for soil. 9 10 Jin D, Jin S, Chen J (2019) Cannabis Indoor Growing Conditions, Management Practices, and Post-Harvest Treatment: A Review. American Journal of Plant Sciences 10: 925-946 11

While many soil companies will advertise their soil as “pH-corrected,” cultivators should always double-check these claims. Use a high-quality pH monitor to verify your soil will support healthy nutrient absorption.

How much soil do you need for cannabis plants?

While examining what’s in your soil is crucial, you also must consider how much soil you need. Nobody likes to have a big bag of unused soil sitting around in their space.

On average, home-growers use a three-gallon pot for each cannabis plant. In this case, most cannabis cultivators recommend about 1.5 cubic feet of soil for three cannabis plants in these containers.

Keep this average ratio in mind when evaluating how much soil to stock up on.

What’s the best soil for autoflowers?

Thanks to their ruderalis genetics, autoflowering seeds are tougher than most photoperiod strains. In fact, many cultivators claim it’s not good to pamper auto seeds with well-fertilized soil. That’s because autoflowering varieties are usually short in stature and have a shorter life cycle.

If you opt to use nutrient-dense soil formulas, it could easily cause “nutrient burn.”

Autoflowering fans should stick with simple potting soil for the best results. Some cultivators also express great success using a mix of peat moss, coco coir, and a bit of perlite for their autos.

Remember autoflowers don’t grow as large as regular cannabis strains. Be sure to factor in your auto’s average height before purchasing a bag of soil.

So, what’s the best soil for marijuana? You choose!

As you start “digging” through all the soil brands online, you’ll find so many options to choose from. From nutrient-dense “super soils” to inert coco coir formulas, there’s no “set soil” for cannabis cultivation. Indeed, finding the ideal soil for your cannabis grow operation will depend on your preferred growing style and the type of plant you’re growing.

Anyone new to cannabis cultivation should probably opt for a simple potting mix. While these may not give the “best results,” they tend to be the most forgiving. As you figure out your preferred growing style, you may want to experiment with flaming “hot” super soils or virtually inert coco coir mixes.

Just remember to constantly track the basics like pH, aeration, and water retention when experimenting with cannabis soils. No matter how advanced your soil claims to be, it will not work if these metrics aren’t in order.

Choosing The Best Soil For Cannabis: A Home Grower’s Guide

Growing cannabis in soil is a great way to crop fat, flavoursome buds. Moreover, soil is one of the most forgiving substrates. What are the best soils for growing cannabis? What do you need to know if you want to make your own soil? Our guide answers these questions and more!

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Home grower’s guide to the best soil for cannabis.

Contents:

  1. What’s the best soil for growing weed?
  2. Traits of quality cannabis soil
  3. Amendments to improve soil quality
  4. Photoperiod vs autoflowering
  5. Store-bought vs homemade
  6. No-till cultivation
  7. Amendments for arid/drought conditions

When growing cannabis, using the right soil is crucial. Unfortunately, sourcing the best soil isn’t always straightforward. From cannabis-specific soils to bargain universal substrates and pre-fertilised types, the sheer amount of options can be overwhelming to novices. And what if you want to make your own soil from scratch?

Let’s talk about the best soil for growing cannabis.

WHAT’S THE BEST SOIL FOR GROWING WEED?

Not every soil is suitable for growing cannabis, and not all cannabis requires the same type of soil. Picking the optimal soil depends on the type of cannabis you’re growing, your climate, whether you’re growing at home or in the wild, etc.

Aside from these factors, there are some common traits among all cannabis soils. Let’s take a look at them:

Texture

Cannabis prefers a light and loose soil texture. A light texture promotes root development, and it ensures more oxygen reaches the roots for optimal growth and health.

Drainage ability

Cannabis soil needs to have excellent drainage. When you water your plants, it shouldn’t pool on top of the soil. If the soil has poor drainage, your plants will get sick and turn out subpar yields, or die.

Water retention

Just as important as good drainage is water retention, which is the soil’s ability to hold water. Good cannabis soil has an optimal balance of water retention and drainage.

pH value

pH is a chemical scale that indicates how acidic or alkaline something is. This is important, as cannabis only does well within a small pH range. A good soil for weed has a pH of about 6.0. A pH of 5.8–6.3 will be fine, but if it fluctuates too far outside of this range, you will get diminished yields. If the pH is seriously off, your plants will die.

Nutrients

Cannabis soil needs to contain nutrients so your plants can grow. Fortunately, almost all soils you can buy already feature them. Know, however, that these nutrients will often last only 3–4 weeks. Around the time your plants start to flower, the nutrients in commercial soils will likely be depleted. This is when you should begin to add nutrients.

If you’re growing without additional nutrients, your soil needs to contain organic substances such as humus, compost, worm castings, guano, etc. Microorganisms in the soil will turn these substances into nutrients for your plants to access on demand.

TRAITS OF QUALITY CANNABIS SOIL

If you’re using store-bought potting mixes, these are already optimally “tuned” for growing. Different story if you’re growing organically, though. Natural soil comes in four varieties: sandy, silty, loamy, and clay. But know that most soils consist of varying ratios of these soil types.

For example, a soil may be clay and loamy, or sandy and silty.

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SANDY

Sandy soil is coarse with good drainage, but has poor water retention. When watered, nutrients such as nitrogen will also quickly get washed away. Sandy soil is easy to work with and is a viable choice for cannabis growers.

  • Coarse structure
  • Low pH
  • Pros: Good drainage, keeps soil airy, high oxygen levels, easy to work with
  • Cons: Poor water retention, needs frequent watering

SILTY

Silty soil is a medium-coarse soil type that’s rich in minerals and organic particles. Its water retention is good, yet it has adequate drainage. Silty soils are very easy to work with. The minerals and organic substances within make it one of the most fertile soil types.

  • Medium-coarse
  • Pros: Contains minerals and nutrients, retains water well
  • Cons: Fair drainage

LOAMY

Loamy soil is a combination of sand, silt, and clay soils with added organic compounds. It is one of the best soil types for growing cannabis as it offers optimal water retention and drainage, and it’s rich in nutrients and oxygen. Downside: This type of soil can be expensive.

  • Mixture of sand, silt, and clay
  • Pros: Excellent water retention and drainage, contains nutrients, high oxygen levels
  • Cons: Expensive

Clay soils consist of fine mineral particles. This type of soil is heavy and not easy to work with. It is very rich in nutrients and minerals, which makes it a good option to include in organic grows. Clay soil retains water well, but has poor drainage.

  • Fine particle size
  • High pH
  • Pros: Rich in nutrients, retains water
  • Cons: Poor drainage, heavy and compact, hard to work with

AMENDMENTS TO IMPROVE SOIL QUALITY

If you’re working with natural soil, chances are it won’t be perfect for growing cannabis—not from the start, at least. The texture may not be optimal or it may have poor drainage, for example. But you can improve any type of soil by adding amendments, most of which can be found in your local grow shop.

COCO COIR

Coco coir (coco fibre) is made from coconut husks. These light fibres provide excellent water retention and can lighten compact soils. Some use a pure coco substrate with special nutrients to cultivate their weed. But to amend existing soil, it’s a good idea to add anywhere up to 30% coco coir, depending on the composition of your base soil.

PERLITE

Perlite is the most widely used soil amendment. Perlite consists of very light, bright-white rocks that greatly improve the drainage and airiness of the soil. Perlite also has decent water retention. To amend your soil with it, add 10–15% of perlite. You can add more, but then your soil may become too light and nutrients may leach out. Good-quality commercial soils often come with added perlite.

CLAY PEBBLES

Most cannabis growers are familiar with using clay pebbles as part of a hydroponic setup. But did you know they can also be used to enhance soil structure? Adding clay pebbles to the bottom of your raised beds and containers will assist with drainage and prevent water from pooling at the base—a large risk factor when it comes to root rot.

Growers can also add clay pebbles to the top of containers and beds to serve as a mulch. Here, they help to trap moisture in the growing medium by preventing excess evaporation. Clay pebble mulch also casts shade over the top layer of soil, suppressing weeds and keeping beneficial microbes sheltered from the hot rays of the sun.

VERMICULITE

Vermiculite, just like perlite, is a heat-treated mineral you can use to make your soil lighter.It is also excellent at retaining water. Although vermiculite shares some characteristics with perlite, the two have opposite uses: Use perlite to increase drainage and airiness, and use vermiculite to increase water retention. Luckily, you can use both, as perlite and vermiculite work well together. Around 10% vermiculite is beneficial.

WORM CASTINGS

Worm castings are normally seen more as a nutritional soil amendment as they contain a plethora of useful microorganisms that benefit growth. But worm castings will also improve the texture, drainage, and water retention of your soil. When amending your soil with worm castings, use about 25–30%.

NUTRIENTS

If your DIY cannabis soil is rich in organic material, you will likely not need to add nutrients to it. As a matter of fact, some growers make the mistake of adding manure and vegetable scraps to their soil to “fertilise” it. This results in soil getting “too hot” for the plants, hurting their development in turn. If you want to put your vegetable scraps to good use in your garden, you first need to compost them.

If you think you need to amend your cannabis soil with nutrients, you can easily purchase bottled solutions tailored to a plant’s phase of growth.

Bat Guano

PHOTOPERIOD VS AUTOFLOWERING

One factor to consider when choosing the right soil for your weed is whether you’re growing photoperiod or autoflowering plants. Autoflowers prefer a light mix with fewer added nutrients. A great substrate for your autoflowering ladies is a 50:50 mix of coco coir and a light, peat-based soil with some added perlite for drainage.

When growing autoflowers, stay away from heavily fertilised soils and certain amendments like bat guano, as these will be too hot and overload your plants with nutrients. The same is true for cannabis seedlings, which do not like high levels of nutrients.

Plant autoflowers in their final growing container in a cup-sized hole in the centre of the soil. Fill the hole with seedling/starter soil with no nutrients and place your seed in it. This way, your seedling can grow without being surrounded by the hot soil, which would otherwise burn it.

For photoperiod plants, start them out in small seedling pots/cups with soil that has little to no nutrients. Replant after a few weeks. More mature plants will tolerate higher nutrient levels much better than seedlings.

STORE-BOUGHT VS HOMEMADE

If you’ve just started growing cannabis, it may be best to simply get ready-made soil from the grow store. The reason for this is that good-quality cannabis soil normally contains everything your plants need for healthy growth, in the optimal ratios. If you want, you can further improve your store-bought soil with a handful of perlite for increased drainage, but otherwise you should be good.

BASIC CANNABIS SOIL RECIPE

On the other hand, there may come a time when you want to make your own soil. After all, why spend good money on soil if your homemade version is even better? Here is a recipe for a basic homemade cannabis soil.

INGREDIENTS
  • 1 part vermiculite
  • 1 part coco coir peat
  • 2 parts compost
  • ½–1 cup worm castings (or humus)
DIRECTIONS
  1. Sieve the compost to remove larger chunks.
  2. Soak the coco coir peat in warm water. Check the directions of the product to see what kind of volume you will be getting.
  3. Use a bucket and mix the coco coir peat with the vermiculite.
  4. Add the compost.

Done! Double-check the pH value of your homemade soil. It should be in the range of 5.8–6.3.

The above is a basic soil recipe that will serve you well for most grows, indoors and outdoors. But you can further enhance your soil mix by adding organic fertilisers.

Bat guano is an excellent and inexpensive organic fertiliser for flowering marijuana. You can add it to a soil mix or spread it on the topsoil and water in later. You can also look into time-release nutrients such as Easy Boost Organic Nutrition pellets. Add a cup of these to your soil to feed your plants for their whole life cycle—100g is enough for 2–3 cannabis plants. All that’s left to do is water!

NO-TILL CULTIVATION

No-till cultivation is a gardening method that allows the soil to remain undisturbed (no digging, stirring, overturning, etc.). This way, microorganisms in the soil can create a thriving ecosystem that replenishes the soil with good bacteria, helpful fungi, and other living organisms. No-till cultivation promotes organic matter retention and water absorption because nutrients are constantly being recycled throughout the soil.

To learn about no-till cultivation and its benefits, check out this article!

AMENDMENTS FOR ARID/DROUGHT CONDITIONS

If you’re growing outdoors in a hot climate such as Southern Spain or a similar location, you don’t want to “cook” the root zone of your plants. If you’re using pots, choose white plastic containers, as these help to keep the soil temperature at a reasonable level under the beating sun. You can also look to air pots or smart pots to keep the roots of your cannabis plants cool. As an additional measure to protect the soil from fluctuating temperatures, you can add layers of dry straw onto the topsoil.

If you’re growing in drought conditions where your plants may at times go weeks without rain, or if you can’t make daily trips to your guerrilla grow location, use water-absorbent polymers to keep them hydrated! You can get these from hydroponic grow stores or can cut them out of diapers.

For a guerrilla grow in dry conditions, dig a hole about 60cm deep and 30cm in diameter. Add a few cups of polymer crystals to the bottom of the soil mix and fill up with the remaining soil. Place your plant into the soil and water liberally. As your plant grows, the roots will soon reach the polymers so it can drink even during drought. Tip: Soak the polymers in a light nutrient solution for a double benefit!