Before a cannabis seed can sprout and grow, it needs a planting medium: soil. Along with water, light, and nutrients, soil is an essential part of any growing operation. It can spell the difference between vibrant, healthy plants and a disappointing, empty grow.
In this article, we discuss the best soil for cannabis plants, whether it’s for indoor, outdoor, or autoflowering plants.
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What Makes a Good Soil for Cannabis?
There are six main types of soil:
- clay,
- sandy,
- silty,
- peaty,
- chalky,
- and loamy.
However, when cultivating cannabis, only four of these types are typically used.
- clay,
- sandy,
- silty,
- and loamy.
Generally speaking, soils used for growing plants such as marijuana will combine these types of soil in various ways. For example, you may find loam-clay, sandy-silt, or clay-silt combinations.
To add to this complexity, soil combinations are also available in different ratios. While this can be overwhelming as a novice at growing weed, you don’t need to become a full-fledged soil scientist to understand what makes good soil for cultivating cannabis.
That’s where this guide comes in.
So, to start, let’s take a closer look at each of these soil types and when you might use them to grow your own marijuana.
Sandy Soil
Sandy soil, as the name suggests, is very sandy. The soil commonly found at beaches is, unsurprisingly, sandy soil.
It’s composed of large, granular particles with lots of space separating them. Because of this, water and nutrients easily wash right through sandy soil, which causes it to dry rapidly and strips it of vital nutrients such as nitrogen.
Nevertheless, this doesn’t mean sandy soil is unsuitable for cultivating cannabis. On the contrary, sandy soil has excellent drainage. In addition, it is typically loaded with oxygen, which is necessary for growing weed.
It’s also easy to work with. But, because of its poor water retention, plants grown in sandy soil will need frequent watering and feeding.
Silt Soil
Silt is a medium-coarse soil with lots of minerals and organic material, primarily quartz. It has significantly more water retention than sandy soils and poorer (but still adequate) drainage.
Silt is also very easy to work with, even while wet.
The organic material and minerals it’s loaded up with make it an incredibly fertile soil that’s great for various crops.
Ultimately, silt is one of the best kinds of soil for growing weed and is especially good for young plants and seedlings.
Clay Soil
Clay is a heavy, nutrient-rich soil. It’s decently tricky to work with but is a popular choice of soil for organic cannabis farmers.
It’s composed of small, very fine particles with a high pH. Clay retains water well but offers very poor drainage, which can make it a difficult soil to work with for beginners. It’s also the heaviest soil on our list, and plant roots may have difficulty penetrating clay.
Despite its challenges, clay is incredibly rich in minerals and nutrients. So with the right set-up, you can still produce extremely high-quality cannabis harvests.
Loam Soil
Loam is not necessarily its own type of soil but a combination of different soils. Loam contains a mix of silt, sand, and clay.
Because of this combo, loam enjoys the best of all worlds. It has the excellent drainage of sand along with the great water retention of silt.
Not only that, it retains plenty of oxygen and is packed with nutrients thanks to the clay it contains. However, like clay, some loamy soils can be a little more challenging to work with than sand or silt. Loam can also be a more expensive option, especially if you’re buying in large quantities.
Regardless, loam is the preferred choice of soil for many home growers and professional cultivators.
Drainage, pH, Texture, and Water Retention
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Now that you know the common types of soil for cultivating cannabis – and their strengths and weaknesses – let’s look at the factors that determine how successful they will be in your home grow.
At the end of the day, there are four main things you need to pay attention to when it comes to choosing the best soil.
These are:
- Water Retention
- Drainage
- pH
- Texture
Water retention and drainage are likely to have the largest impact on your plant yields.
Healthy marijuana plants will require a constant supply of water and oxygen. However, water and oxygen ultimately compete for space within the soil.
For example, if there’s too much oxygen (like in sandy soils), there won’t be much water, and vice versa. On the other hand, if the soil contains too much water (as can happen with high retention, low drainage clay soil), your plants could develop root rot.
You’ll also want to be mindful of the texture and the pH of your choice of soil.
The texture of the soil will ultimately determine how well the plant roots can spread out and grow. For instance, something like sand is very loose, allowing the roots to grow and spread easily. However, if too loose, the texture may not support the plant very well, especially as it gets bigger.
On the flip side, plant roots may struggle to penetrate and spread through hard, heavy textures, like clay.
Finally, consider your soil’s pH. Like many plants, marijuana grows best in slightly acidic soil with a pH of less than 7.0.
The optimal range you should shoot for is 5.8 – 6.2. Luckily, this is pretty easy to maintain if you regularly use a pH meter and adjust your fertilizer solutions as necessary. And if you want things even easier, stick with loam, as its composition naturally strikes a balance between water retention, drainage, texture, and pH.
What is the Best Potting Soil for Cannabis?
Given all these essential factors for soil quality, an entire industry has emerged to provide cultivators with an ample supply of marijuana-specific potting soils.
These potting soils are typically rich in nutrients. In addition, they contain a mixture of soil types in ratios ideal for healthy cannabis growth.
Given the complexity of soil science, we wouldn’t blame you for wanting to buy a pre-made mix and jump into growing weed without worrying about soil quality.
In fact, it’s recommended for most novice growers because replicating these pre-made soil mixes with all the same macronutrients, micronutrients, and ideal qualities can make your growing process much more complicated.
Here are a couple of our favorite cannabis potting mixes you can try out for yourself. And if you want to make your own soil, we’ll tell you how at the end of this article.
FoxFarm Ocean Forest Potting Soil
Ocean Forest Potting Soil is excellent for pots, containers, or grow bags. Ocean Forest is pH adjusted at 6.3 to 6.8 and is loaded with nitrogen.
Coast of Maine – Platinum Grower’s Mix, Super Soil, Stonington Blend
Coast of Maine is one of the all-time favorite soil brands for many cannabis cultivators. The company’s Platinum Grower’s Mix is a ‘super soil’ with a remarkable nutrient composition. This soil is loaded with organic material – such as lobster compost, mycorrhizae, alfalfa meal, and worm castings – to help your plants thrive.
Organic Super Soil Concentrated Strength
If you’re looking for the highest quality potting soil for your cannabis plants, look no further than Organic Super Soil. This potting soil is packed with organic earthworm castings, high-quality bat guano, blood meal, bone meal, fish bone meal, alfalfa meal, kelp meal, dolomite lime, azomite, and a grand total of nearly 50 organic materials.
What is the Best Soil for Growing Cannabis Outdoors?
Depending on where you live, your local soil’s conditions may be ideal for growing cannabis outdoors. But, of course, this isn’t always the case.
The best soil for outdoor grows is essentially the same as the best soil for growing indoors. That is, it should be loamy, light, with good drainage and water retention.
According to many growers, the best soil combination is a mix of silt, sand, and clay at a ratio of around 40:40:20.
Unless the soil in your backyard is naturally very loamy, you’ll want to supplement the local soil with more sand, silt, or clay to achieve the proper conditions necessary for the best outdoor yields.
Mixing in more gravel can also help improve the drainage of your soil, if necessary.
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Here are our favorite outdoor cannabis soils you can try if you need to mix with your local soil to strike the right balance of water retention, drainage, pH, and texture.
Black Gold 1311002 8-Quart Seedling Mix
Black Gold is a favorite among outdoor cultivators and is a well-known company in the cannabis industry. This particular soil is well suited for outdoor growth because it is highly nutritious and deeply oxygenated.
Unco Industries WWSB30LB Wiggle Worm Soil Builder
As the name suggests, Wiggle Worm Soil Builder is rich in worm castings (the fertilized soil produced by earthworms – aka their poop). But worms have long been the natural fertilizers of outdoor soil and play a vital role in the ecology of many plant systems, including cannabis.
Epsoma DB3 Dried Blood Meal
Believe it or not, animal blood is a very effective fertilizer for many plants. This is because animal blood meal is rich in nitrogen, which cannabis plants need lots of for healthy growth and big yields.
This Epsoma product is a dry powder containing blood meal that you can add to your soil mix to help boost healthy plant growth.
What is the Best Soil for Growing Cannabis Indoors?
There are many different indoor cultivation setups and methods, such as light deprivation, micro-growing, and hydroponics (which require no soil at all). These methods may need their own soil conditions. But generally speaking, the best soil for indoor cannabis cultivation should have the same qualities as outdoors. It should be relatively loamy, with proper drainage, and retain water well.
Thankfully, choosing the right soil for an indoor grow doesn’t have to be complicated. Many cannabis potting mixes and soil products are specifically made for indoor cannabis growth.
Here are some of the highest-rated indoor soils.
Mother Earth Terracraft Potting Soil
If you’re looking for an all-around, high-quality potting soil for your indoor cannabis plants, then the Mother Earth Terracraft Potting Soil is a solid choice. Not only is it great soil for indoor plants, but it’s also excellent soil for all different growing methods.
It’s packed with eight primary nutrients that’ll help your marijuana plants thrive.
Purple Cow IndiCanja
If you’re interested in organic indoor cannabis growing, Purple Cow IndiCanja is a popular, water-only soil choice among professional cannabis cultivators.
You simply plant your seeds or seedlings and water them without adding nutrients.
Brut Super Soil
To help maximize your indoor harvests, Brut Super Soil contains everything your cannabis plants need to thrive, including coco fiber, peat moss, perlite, sand to worm castings, cow manure, and a plethora of beneficial microbes.
What is the Best Soil for Autoflowering Cannabis?
Finally, autoflowering cannabis plants have slightly different soil needs than typical plants.
Typically, cannabis plants will begin flowering once they are exposed to less light than they’re used to during the vegetative stage. But autoflowers automatically start flowering at a specific time after completing the vegetative growth phase.
It’s all about time and not light.
Generally speaking, autoflowers will start flowering approximately one month after their seed germination. After that, their growth may only last another month or so before it’s ready to be harvested.
This relatively short life cycle means that autoflowers need lighter and more oxygenated soil than the typical loamy soil best for other cannabis plants. Not only that, they need a smaller amount of nutrients.
If you were to treat the soil of your autoflowers the same as you would a typical marijuana plant, you could experience a greater risk of nutrient burn or Hypoxia (lack of oxygen).
Super Soil Autoflower Concentrate
Given these unique constraints on autoflower cannabis plants, its worth purchasing soil that’s specifically designed to cater to their growth.
We recommend Super Soil Autoflower Concentrate. As the name suggests, this soil was mixed with autoflowers in mind, and it can be used in whatever growing medium you choose – whether it’s indoors or outdoors.
It’s also packed with vital nutrients, microorganisms, fungi, and more that’ll help boost plant growth and support root health.
How to Make your Own Organic Soil for Cannabis
It’s also possible to make your own organic soil. Here’s how:
- Clear a 3-foot by 3-foot space on the ground,
- Cover this space with a carbon material of your choice; hay or old tree leaves work well. Be sure that this carbon layer is at least 4 inches thick,
- On top of the carbon layer, add your nitrogen material. Many growers use old coffee grounds, manure, or compost. This layer also must be 4 inches thick.
- Finally, add phosphorus – often in the form of bone meal – into your organic soil..
- Duplicate these four steps until you’ve created a soil pile at least three feet in height.
- After this, you’ll need to be patient and wait. The pile will begin to decompose over time.
- Once every seven days, return to the pile and turn and mix it up a little.
- Eventually, the pile will begin to look like dirt or potting soil. You’ll know it’s ready if it’s dark brown or black, smells sweet, and is soft.
- Use this soil to plant your marijuana seeds or seedlings.
The information in this article and any included images or charts are for educational purposes only. This information is neither a substitute for, nor does it replace, professional legal advice or medical advice, diagnosis, or treatment. If you have any concerns or questions about laws, regulations, or your health, you should always consult with an attorney, physician or other licensed professional.
Source: https://gardencourte.com
Categories: Outdoor
