Growing Marijuana in Soil Indoors: All You Need to Know

Cannabis Plant growing indoors in soil
November 16, 2020

Growing marijuana outdoors is the most natural approach, but not always possible. Apart from legality concerns, not everyone has a suitable spot for an outdoor garden. Or, the local climate may not be conducive to plant growth. The next best thing, in this case, is to bring the plants inside the house – and to grow them in soil.

A Guide to Growing Marijuana Indoors in Soil

Despite the rise of soilless substrates and hydroponic systems, soil medium remains the most popular growing medium for cannabis plants. It is, after all, the natural habitat of most flora and used for gardening since ancient times. Moreover, it is widely available and effortless to use.

Soil, as a growing medium, does its job pretty well. Primarily, it supports plant growth by providing the following:

Anchorage. It acts as structural support, keeping the plants in space as the root systems grow and expand.

Oxygen. Soil contains pore spaces that facilitate oxygen intake, which helps break down sugars into energy that the plants can use to grow and survive.

Water. Aside from air, the spaces between soil particles also hold moisture and assist with water transport, ensuring that the plants remain amply-hydrated at all times.

Nutrients. Soil is naturally fertile and contains a range of minerals. More than that, it also holds onto the nutrients that you add in the form of fertilizers.

Insulation. Soil is an excellent insulator, safeguarding the roots against extreme temperature changes – a critical function during excessively hot or cold seasons.


Growing cannabis in soil is rewarding in many ways. For one, it is straightforward and does not require any complicated equipment or technical expertise. With some preparation, it does not take long for even beginners to grasp its nitty-gritty.

Soil is also a forgiving medium – another reason why experts highly recommended it to novice cultivators. It gives you more leeway to experiment and learn. Even if you make mistakes, troubleshooting will be a breeze because of the wealth of resources available online. Growing indoors lets you easily manipulate the environment so that the plants can quickly bounce back to normal.

But it is not just the process itself that is appealing – but the results as well. Soil-grown cannabis also produces the most flavorful and aromatic buds. You can rest assured that the consumption experience will be as gratifying as you imagined it.

In summary, here are the top advantages of growing marijuana in soil:

  • Straightforward
  • More forgiving to mistakes
  • Cheap setup costs
  • Ideal for beginners
  • Easy to troubleshoot problems
  • Better flavor profile


Just like any endeavor, using a soil substrate also has some drawbacks. Being organic, for example, makes it more likely to attract pests. And if you get your soil from unreliable sources, you may unwittingly use a medium contaminated by diseases, weed seeds, insects, and parasites. You risk passing these on to your plants.

Marijuana plants in soil generally grow slower than soilless or hydroponic systems, especially in the vegetative stage. Aside from that, the yields also tend to be lower. Several training methods, though, can help coax out a greater harvest.

In summary, here are some of the disadvantages of growing marijuana in soil:

  • May carry pathogens and weed seeds
  • Increased risk of pest problems
  • Slower growth
  • Lower yields

Preparing the Soil

Plants thrive in a specific type of soil. It means that you cannot just use any random dirt lying in the garden.

Here are the markers of good-quality soil for marijuana:

  • Loose and friable
  • Nutrient-rich
  • Full of organic matter
  • pH-balanced
  • Moisture-retentive
  • Well-draining

By itself, though, soil typically does not possess these traits. It is most likely too light or too heavy. Or, it may not have enough organic materials to encourage the microbial populations in the soil. As a workaround, you would have to amend it with the appropriate ingredients.

Worm castings, coco coir, and perlite, for example, can improve its texture, moisture retention, and drainage. It ensures that the root zone has adequate access to oxygen, water, and nutrients at all times. To bring the pH to suitable levels, consider adding garden lime, wood ash, or biochar. And if you want to boost the microorganisms, simply enrich the soil with organic matter, such as worm castings, compost, blood meal, and other types of plant- and animal-based products.

You can also opt for loam soil – dubbed as the “Holy Grail of soils.” It contains a balanced blend of sandy, silt, and clay soils, resulting in optimal structure, water retention, and drainage. When squeezed into a ball, it should hold the shape for a few seconds before breaking apart into chunks. That indicates that it is neither too dense nor too airy. While loam soil holds a range of nutrients, you would still have to use separate fertilizers to meet the plants’ dietary needs.

Alternatively, you can also buy high-quality organic potting soils. You will never go wrong with these products from FoxFarm and Roots Organics.

Choosing the Container

After prepping the soil mix, the next step is to find where to put it. When growing indoors, you do not have the option of planting directly on the ground. You would need pots or containers. These come in varying types and sizes.

Pot Type

You can choose from several types of pots. Mainly, they differ in the materials used and perforation mode. As a result, they have different aeration, moisture retention, and drainage capacities. At any rate, one is not necessarily better than the other. It all comes down to your needs and preferences.

Marijuana growers swear by the following pot types:

  • Clay pots
  • Smart pots
  • Air pots

Clay pots are recommended if you only plan to use a single container throughout the growing cycle. That is because it is prone to breakage, which makes transplanting difficult.

Both smart and air pots encourage aeration and drainage, making them challenging to overwater, but they are faster to dry out. It means that you may have to drench the plants more frequently.

The main difference between the two is the material used. One is fabric – smart pots – while the other is rigid plastic – air pots. While both types are lightweight, air pots are easier to handle since they are more structurally stable.

Smart pots, on the other hand, are not made of a stiff material, making it more easily mishandled. In turn, this increases the risk of damaging the fragile roots. For this reason, it is more often used as the final container.

Pot Size

With cannabis seedlings, it is recommended to start with a solo cup or a one-gallon pot. Upon outgrowing the current container, you can transplant the young plants to a bigger pot. It should at least be double the size of the previous one. 2- to 3-gallon ones are the most common.

In the late vegetative stage, you can move the plants to their final home. To know the size, consider the typical height of your chosen strain. As a rule of thumb, the plants will need two gallons of soil for every twelve inches of growth.

If you are growing autoflowering seeds, you need to use the final container from the very beginning. That is because their short life cycle does not leave any room for healing if they get transplant shock.


Watering marijuana plants in soil can get tricky – especially for beginners. After all, there are no specific guidelines to follow. Instead, you would have to take several factors into account to know precisely when and how often you should irrigate the plants. That includes the local climate, temperature, humidity, pot type and size, and plant size, among others.

Generally, the warmer the temperature, the faster the evaporation rate. It means that you would have to water more frequently. Also, the more mature the plants are, the higher their moisture requirements.

As a rule of thumb, water the plants when the top 1-2 inches of the soil feels dry to touch. In most cases, it means watering every 3-4 days. Again, you may have to do it less or more often, depending on your situation.

So, how should you water the crops?

For the typical home grower, the good old watering can suffice. Fill it with pH-balanced water that is neither too warm nor too cold. Keep in mind that if your area has hard water, you would have to treat and filter it before use.

Once ready, drench the plants slowly yet deeply, focusing on the plant base. Keep at it until 10-20% of the liquid drains out.

Ideally, the water should not pool on top of the soil or take too long to seep out of the bottom holes. If so, your soil might have poor drainage. Try combining it with lightweight materials, such as perlite and sandy soil.

Nutrients and Feeding

Soil is unlike any other growing medium in that it houses millions of beneficial microorganisms. These, in turn, feed on plant debris and organic matter, eventually producing nutrients and minerals that the roots can readily absorb and use. Make sure to capitalize on this symbiotic relationship. Do this by nourishing the soil with organic nutrients, such as compost and worm castings.

For convenience, you can also go for professional blends. Some of the most reputable brands of organic fertilizers include Dr. Earth, FoxFarm, and Jobe’s Organics. At any rate, steer clear of harsh chemicals at all costs. These could kill off the microbial life in the long run. Even worse, the toxins could be passed on to humans upon the consumption of tainted buds.

More importantly, be aware of the nutrient needs of cannabis plants across the different growth stages. Also, dose carefully and maintain ideal pH levels. These can help prevent nutrient problems, including deficiencies, toxicities, and lockout.

A Tried-and-Tested Way of Growing Top-Quality Marijuana

Growing in soil is a classic practice that has withstood the test of time. This rings true even with the rising popularity of hydroponic systems. Soil, after all, is as fuss-free as it could get. It is also cheap and incredibly forgiving for novice growers. More importantly, in terms of results, it more than delivers. With proper care, you can rest assured that the buds will be as potent, aromatic, flavorful, pure, and clean as can be.

Black leaves
Welcome back! It’s nice to see you again! Log in to continue to your account.
Black leaves
It seems like you’re new here.
Please create an account.
Your subscription has been confirmed. You’ve been added to our list and will hear from us soon.