The Best Soil for Growing High-Quality Cannabis – 2021 Guide

best soil for cannabis

The Best Soil for Growing High-Quality Cannabis – 2021 Guide

When nurturing cannabis seeds, one of the first choices you will have to make is what growing medium to use. There are many choices that each have their own benefits — including compost, soilless mixes, and hydroponics. Today, we’ll be focusing on the best soil for cannabis.


Choosing the best soil depends on factors such as water retention, pH value, and whether you’re growing indoor or outdoor cannabis. Taking care of marijuana or hemp plants can be a wonderful experience, but poor soil can cause stunted growth, weak plants, and a host of other problems. Let’s take a look at the best soil for happy plants!



Is Soil Important When it Comes to Cannabis Plants?

Yes! The right soil is crucial for growing cannabis because it provides the plant’s root system with adequate nutrients and living conditions. A good potting mix is similar to a cozy home and a warm meal for our plants. You show proper plant care by giving your plant a spacious home and healthy diet by choosing the best potting soil.


The most important thing to remember when searching for good cannabis soil is that not all potting mixes are intended for the same use. Some are designed to be used with liquid nutrients. You should not use soil with excellent water retention if your cannabis seeds need good drainage.


All of these variables may sound daunting, but rest assured that your plant will thank you in the long run. Happy cannabis plants are more likely to produce large flowers bursting with beneficial properties. If you’re hoping to harvest top-shelf buds from your plants, good soil is crucial!



What Types of Soils Are There?

There is a difference between natural soil and potting mixes. Plants need more nutrients than those they receive from photosynthesis, and they get that nourishment from their growing medium. Potting mixes are designed to provide these nutrients to a plant’s roots, but natural soil needs a little help.


These are the most popular types of natural soil and their best uses:


  • Sand: This is a good choice for cannabis growers because it is easy to work with. Its large granular size (this refers to the individual pieces of sand) means it has good drainage but poor water retention. This means nutrients will quickly get washed away when you water your plants. On the other hand, it keeps the soil airy and lets the root system get plenty of oxygen.
  • Silt: Silt soil has a medium granular size, so it has better water retention yet poorer drainage than sand. While nutrients wash away in sandy soil, silt naturally contains nutrients and minerals. It is also very easy to work with, making silt a popular soil for growing cannabis.
  • Clay: With a small granular size and a high pH level, clay soil is very rich in nutrients and minerals. It is the opposite of sand in that it has excellent water retention but poor drainage. Clay makes good organic soil due to its rich nutrients, but it is also heavy and difficult to work with.
  • Loam: Loam soil mixes contain a combination of sand, silt, and clay. It has a near-neutral pH, which is ideal for hemp and marijuana plants (we’ll go over the ideal pH levels for cannabis in a section further down). It offers a good balance of drainage, water retention, and nutrients. The only downside is that loam soil can be expensive.



What is the Best Soil for Cannabis?

The best soil for growing cannabis depends on the plant’s climate and environment. For example, soil with poor drainage may not be ideal for indoor plants. Though, it could be one of the best options for cannabis grown in dry and arid climates where water retention is a more pressing concern.


We’ll look more closely at the best soils for indoor vs. outdoor cannabis plants in the next sections. Another important factor to consider when choosing the best soils is whether you’re growing photoperiod or autoflowering plants. This is a genetic distinction that affects when flowers develop.


Photoperiod plants don’t produce flowers until their light cycle changes. which indoor cannabis growers simulate by dimming their lights. Autoflowers are “programmed” to flower more quickly. Photoperiod plants take longer to grow, but their yields are higher than autoflowers.


Since autoflowers don’t rely on seasonal changes, they flower fast and make a great choice for those new to growing marijuana. Autoflowers enjoy a light soil mix that drains easily and doesn’t have too many nutrients. Try to avoid heavily fertilized soils, as these may overwhelm autoflowers with nutrients.



hands cupping a cannabis seedling in a container of dirt



What is the Best Soil for Indoor Cannabis?

The best indoor soil contains all of the nutrients that a cannabis plant would receive if grown outside. Since indoor plants don’t have as much room for root development, choose a soil type that isn’t too compact.


Soil made with beneficial microbes is also ideal for indoor cannabis since it promotes healthy root growth. Look for ingredients such as worm castings (a fancy term for worm poop) and bat guano (a fancy term for bat poop). These make high-quality soil for any indoor grower.


What is the Best Soil for Outdoor Cannabis?

When it comes to growing cannabis outdoors, one of the major advantages over indoor setups is that you have a free source of soil and light. If you live in a fertile area, Mother Nature already provided you with a soil mix that has more than enough nutrients for high-quality cannabis.


Whether you use the great outdoors’ soil or purchase your own, you’ll want to make sure it is rich in nitrogen, potassium, and phosphorus. A living soil (one that centers on compost) is ideal, but keep in mind that a cannabis plant needs less nitrogen when it’s blooming.


If you do buy soil, try to avoid slow-release mixes. This type of soil slowly releases nutrients, and it may provide nitrogen to your plant even when it begins to bloom.



How to Choose the Best Soil for Cannabis

The best cannabis soil is any mixture that will result in the healthy growth of your plant. Since this can mean something different to growers in various climates and environments, let’s examine each aspect of soil. This will help you amend your soil in whatever way you need to grow the best possible cannabis!



A soil’s texture is crucial for your plant’s root growth. Without enough room to grow, the roots could get oxygen-deprived, dehydrated, and possibly die. Choose a cannabis soil that is light and loose so that your herb has plenty of wiggle room.


If your soil is too compact, you can increase its airflow through various methods. Poke chopsticks through the soil to break things up and promote air circulation. Some soil mixes come in a bag that can double as a well-ventilated growing container.


Air pots and smart pots are also excellent choices for promoting aerated soil. Smart pots are made of porous fabric that promotes oxygenation, and air pots are peppered with holes that allow air to flow through the soil. These containers require more watering, but healthy roots are worth it.


Water Retention

Water retention refers to a soil’s ability to hold water. A good cannabis soil will set some water aside so that the plant’s roots have something to sip on for a few days. If you water your plant and notice that it immediately comes out of the drainage holes, the soil’s retention may not be to blame.


Water may run through a pot quickly if the plant and soil are dehydrated. In this case, water the plant every 10 minutes (3 times usually does the trick) until it begins to retain some of the liquid. If nothing comes out of the bottom of the pot, but the plant still isn’t getting enough water, the soil may have poor drainage.



The looser a soil and the bigger its granular size is, the better it will drain water. Cannabis requires a balance between excellent drainage and good water retention. If you pour water into your plant’s pot and notice pools forming on top of the soil, it does not have decent drainage.


Retention and drainage are closely related, but one does not always imply the other. If your soil has excellent retention, don’t assume that it automatically has excellent drainage. Retention refers to the individual particles’ ability to soak up water, while drainage has to do with particle size.


pH Value

A soil’s pH value describes how acidic or alkaline it is. The pH scale ranges from 0-14, with zero being extremely acidic, 14 being the most basic, and seven being neutral. Cannabis requires a near-neutral pH level that is slightly acidic, so your soil should fall between the 6-6.8 range.


It’s essential to find the right soil with this ideal range to begin your grow. If you use liquid fertilizer, you may need to monitor the pH of your soil during your plant’s growth. Some growers use lemon juice or phosphoric acid to buffer pH if they find their soil to be too basic (above 7). Dolomite lime is another great additive that can regulate pH.



a gloved hand holing a ph test strip




Plants need to eat more than light and water, so we have to ensure their soil contains plenty of nutrients. Organic potting soil usually has these nutrients, but they are depleted within three to four weeks. This is when cannabis begins to flower, and so the plant will need additional nutrients at this stage.


Microorganisms in the soil will turn organic material into usable nutrients. Provide your soil with ingredients like humus, bat guano, and worm castings. Liquid nutrients can also help your plant grow, though you should only use these sparingly (every other watering).



What Are the Best Soil Ingredients for Cannabis?

Cannabis requires a growing medium that can hold moisture, drain properly, and provide plenty of nutrients. Adding ingredients is known as “amending” the soil, and they are typically used to assist a plant’s nutrition. But, some ingredients can also boost soil retention or drainage.


Terms like coco coir, perlite, and worm castings may seem odd, but rest assured that they can all drastically improve your plant’s health. The best ingredients for good cannabis soil include:


  • Coco coir peat: Also called coco fiber, this is made from coconut husks. Used to lighten the soil.
  • Perlite: Light rocks that improve aeration and drainage.
  • Earthworm castings: Worm poop may not be the most appealing ingredient, but a cannabis plant’s roots can’t get enough of it.
  • Fish meal: Extracted from fish, used for nutrition.
  • Bone meal: Ground-up animal bones that are packed with nutrients.
  • Blood meal: Powdered blood that makes for excellent fertilizer.
  • Bat guano: Nourishing bat droppings.
  • Peat moss: Dead fibrous material made from decomposing moss; works as good plant food.
  • Dolomite lime: Derived from the combination of calcium carbonate with magnesium carbonate, this is an alkaline mineral-rich substance that can help get your soil’s pH to a desirable level.



What Traits Make the Best Soil for Cannabis?

The most vital traits of a high-quality cannabis soil are a pH level of 6-6.8, a good balance of drainage and moisture retention, and organic matter. This is often referred to as super soil, which is an amended mix with everything a plant needs.


Some companies will claim that organic super soil is the best growing medium for your plant. In terms of plant growth, the difference between all-natural organic ingredients and synthetic chemicals is up to personal preference. Both non-organic and organic soil will take care of your plant well.


Should you add any additional nutrients to the soil?

Growing cannabis in soil rather than a potting mix, compost, or hydroponic setup means that you have to keep an eye on the nutrients your plants receive. While super soil can provide the plant with beneficial nutrients, they will eventually be depleted.


When the soil loses its fertility, you’ll need to administer additional nutrients. While we recommend avoiding slow-release soils due to their excessive nitrogen supply, slow-release nutrients can be a beneficial additive to an existing soil mix. This way, you can choose a healthy potting mix to get you through the bulk of the plant’s growth cycle and only add slow-release nutrients when necessary.



Final Thoughts – Best Soil for Cannabis

Growing cannabis is a fun and relaxing process that lets us connect with our plants. In the modern world, we often don’t get a chance to cultivate the things we consume, but taking control of our buds is the first step in changing that. Choosing the right soil for your bud results in a happy plant and, after harvest, a happy you!

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