Growing cannabis on soil indoors

Growing cannabis on soil indoors
Max Sargent

Of all the ways people grow cannabis, growing in soil is the most common. If you want to find more about the pros and cons of soil follow the link.

The natural way cannabis grows is outdoors, under the sunlight and in soil. Most people choose soil as a medium for their first cannabis grow, sticking with the basics and trusting thousands of years of accumulated agricultural knowledge. These basics are so effective that even veteran growers opt for soil as their medium.

Being that soil is such a common medium there is a widespread misconception that all you need to do is buy some good soil, put your plant in it and off you go. However, things don't work that way and you will need to pay attention to detail to get the most out your soil and thus your cannabis plant.


When cannabis grows in soil outdoors it will stretch out its roots through it, looking for water and nutrients. Growing indoors the root space will be much smaller and it will be up to the grower to supply the plant with aforementioned water and nutrients.

Not only that, but the size of the plant's root system dictates the possible size of the plant. In other words, the bigger the container, the bigger and easier will your plants grow.

Due to the fact that cannabis roots have a finite space to grow indoors, you need to make sure that you have a good quality soil or soil based medium to provide your plant with optimal growing conditions.

High quality soil should be aerated well, it should be at a warm temperature of around 20 degrees C, have a pH value of 5.8-6.5 and water should be cycled and drained regularly so that it doesn't become stagnant.

You should also have in mind the nutrient or NPK ratio of the soil, which is the ratio of nitrogen, phosphorus, and potassium – three essential nutrients needed throughout the plant's lifecycle.

Whether you choose a soil that is fertilized in advance or not is completely up to you as both are viable options for growing.

The biggest advantage of soil is that it is cheap and easy to use and maintain. It is more forgiving than other mediums as you don't need to be quite as careful as with other, more complicated methods such as hydroponics.

Growing in soil is conventional and you will have an enormous knowledge base from which you can troubleshoot your problems and deal with them.

On the downside, soil is dirty and takes up a lot of space. It is a good idea to sterilize your soil due to various pests and insects that can find their way into your medium without you noticing. And if you are dealing with a very limited space then it might be better to consider some other options rather than soil.


Soils are mostly comprised of three types of mineral particles and organic material such as decomposed plant matter. The three different (according to size) types of mineral particles are sand, silt, and clay.

Except for the size, they differ in toughness, how they retain water and nutrients and other characteristics, but most soil based mediums have at least one of them in their composition. For instance, loam is a standard soil that can be bought in shops that is great for growing cannabis and a common practice both in gardening and in agriculture. The composition of sand, silt, and clay in loam is 40:40:20 and that is an example how we tell apart different types of soil.

Another thing that should be mentioned when discussing different types of soil is super soil. Super soil is a unique type of organic soil that tries to imitate natural soil conditions. Compost is utilized to make a thriving microbiological environment that will take care of your nutrient needs as this "living" soil will supply all the nutrients needed for the plants by itself. However, making super soil is a complicated and time-consuming process that will take a couple of months, so it is not recommended for beginners.

As you see, mixing your own soil shouldn't be a problem. All you have to do is decide what ingredients you will mix and in what ratio, based on what you want to grow and how you want your soil to behave (more acidic or more basic, should it drain or retain water and nutrients etc.).



Due to the organic composition of soils in nature, they contain a sufficient amount of nutrients for plants to grow successfully. Materials like animal remains, excrement and rotting plant matter provide the soil with all the nutrients plants need, but require additional processes before they decompose and can be absorbed by the roots. Worms, insects and water help in furthering the decomposition process.

Unfortunately, indoor growers will have a hard time duplicating these conditions (as mentioned earlier, creating super soil is a painstaking and time consuming process). But, you can choose to grow your plants in nutrient rich soil that is suited for your needs.

Watch out for the NPK ratio of soils, making sure that you have the right amount of needed nutrients. An important thing to notice concerning nutrients in the soil is that the pH value of the soil is in direct correlation with the absorption of said nutrients. The optimal values of pH will maximize nutrient absorption and you can use chalk or Epsom salts to control the pH of your soil.

Humans have planted in soil for thousands of years and the accumulated knowledge concerning growing plants in soil is vast. It is still the most common medium for growing and cannabis growing ain't no different. From beginners to professionals, many people choose soil as their medium because it is cheap, really easy to use and very effective. Still, it takes a little bit of preparation and care to maximize the potential of your soil. As with all things in life, treat it with care and it will give back.

Max Sargent
Max Sargent

Max has been writing about cannabis and psychedelics for several years now. With a strong belief that an open, honest attitude toward drugs and drug policy can improve the lives of many, he seeks to offer insightful and developed opinions on the subject.