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Indoor Marijuana Growing In Soil

Indoor Marijuana Growing In Soil

Indoor marijuana growers face a unique dilemma when deciding how to grow their crop: should they grow in soil or in a hydroponics system? If you haven’t before considered a hydroponics system and you have a larger budget, you may want to look into it.

Many growers opt for soil when they are starting out. This is a good way to get to know the plant and how it functions, without over-investing in the process. You can grow a fully biological product, and you get to take advantage of all the agricultural knowledge humans have accumulated over the last several thousand years. Pretty neat, right?

Whichever method you choose, you should do the proper amount of research to ensure that your harvest is successful. This article covers the pros and cons of growing marijuana on soil.

Growing cannabis in soil

Growing weed on soil

Out in the wild, the roots of the Cannabis plant will stretch out long distances over time, seeking water and the nutrients required to thrive. Indoor growing, however, requires a much smaller root system for both convenience and simple space required. It’s up to the grower to make sure the plant is being supplied with adequate amounts of water and nutrients. They just don’t have the space for expanding their root systems. Be sure that the temperature around the roots is warm enough (~68 degrees F), that the roots are well aerated, and that the water is being cycled and drained regularly so that it won’t become stagnant.

Advantages and disadvantages

Advantages disadvantages soil cannabis

It’s easier to irrigate plants in soil, or more forgiving at least. You don’t need to be quite as careful as you do when watering plants in hydroponics systems. Plus, the fertilization is easier to deal with in soil. It’s conventional, and so you can draw on a huge knowledge base. If you’re having issues, you’ll be able to troubleshoot them reliably. Different soils can also impart enjoyable and unique flavors to your harvest, which can frequently be a huge plus (although not necessarily).

Download my free marijuana grow guide at this link for more grow tips

Unfortunately, dirt is heavy, and it takes up a lot of space. This is a problem for a lot of indoor growers who only have limited space. Plus, dirt is, well, dirty. Your chances of getting insects or pests goes up substantially when you use a soil substrate for your Cannabis plants.

The factare, some people just aren’t gardeners. There’s a certain sensibility that goes into planting seeds in soil and coaxing the up into beautiful towering plants. If soil isn’t working for you, consider the finely tuned science of hydroponics systems.

Sizing a container

Size container soil cannabis

The size of your Cannabis plant will correlate directly to the size of its root system. This means that the more space your plant has to expand its roots, the more easily it will grow. If the Cannabis plant ends up being too large for the pot, you will run into issues with nutrient and water absorption. Your plant will have a minimized efficiency, and the soil will likely burn through water quickly.

In general, if you have an average Cannabis cutting or seedling, a pot with dimensions of roughly 10x10x10 cm will be large enough for you. If the plant has reached the height of 25-35 cm (especially if it hasn’t stopped growing), you’ll need a pot that’s roughly twice as large, around 15x15x20 cm. If your plant grows larger than 80 cm, you’re going to need a pot that holds at least 10-12 liters. Once the plants reach any size larger than a meter, the size of the pot increases accordingly.

Repot the plant when necessary (and carefully) as it matures.  Remember to keep an eye on the plant as it grows. If your plant never has room to get bigger, it never will. Check this link for the best pots to grow marijuana.

Nutrients for soil

Soil nutrients for cannabis

Soil contains a wide range of naturally occurring ingredients because of its organic composition. A lot of the nutrients available in rotting vegetable matter and animal remains right away, however, requiring additional processes to break them down before they can be absorbed by the roots. Worms and insects aid in the decomposition process, breaking down the materials into a smaller form that the plants can absorb. Rain also helps in the decomposition process. Water is a very effective solvent; it can dissolve materials and make them available for absorption.

Unfortunately, all of these natural processes can be difficult to duplicate for indoor growers. The best bet is to start out with nutrient rich soil and to make sure the soil has been sterilized before you begin potting your plants. Sterilizing your soil with heat won’t guarantee that you’ve killed every possible parasite and disease, but it’s an important preventative step. All it takes is one nasty parasite to spread around and ruin your entire crop.

You can purchase a potting soil mix at a garden shop or mix your own. In either case, you’ll want to create an environment with plenty of oxygen, a temperature around ~20 degrees C, adequate water (moist but not wet), a pH value of 5.8-6.5, and plenty of nutrients. Read the article "Measure pH and TDS of your soil" and learn how to measure the pH and TDS of your soil.

If you’re growing indoors, be careful to meet all the requirements of the soil. The acidity, humidity, and nutrients available in an environment will determine a great deal when it comes to your plants success. A proper pH value in your soil will maximize the absorption of nutrients. You can use chalk and Epsom salts to change the pH of your soil. Or you can buy pH-up and pH down at this link here.

Water retention is also very important in your soil: if your soil drains water without retaining it, your plant will get thirsty fast. If there’s too much water, fungus could grow in the soil and damage the roots. Consider modifying your soil with vermiculite, sphagnum moss, turf, or perlite if you want to change how your soil retains and drains water.

You’ll also want to make sure you have the right amount of nutrients. Lots of nitrogen, a moderate amount of potassium and phosphor.

Making your own soil

Make your own soil indoor cannabis growing

One of the nicest things about soil is that you don’t need to be an expert to mix your own. It’s pretty simple, as long as you follow some basic rules about ratios. The sort of soil you want will vary depending on the stage of growth your plant is experiencing. For example, during the early phase of growth, you’ll want a soil mix made up of equal parts turf, perlite, and worm meal. For growth and flowering periods, use equal parts turf, worm meal, and compost.

If your pH is rising too high, you can add some chalk to bring it back down. Also, you can easily add liquid fertilizers into your plant when to water. If you plan to make your own liquid fertilizer, make sure you have it mixed well. If the mixture isn’t well-balanced and homogenous, your plant will absorb nutrients unevenly and could experience a nutrient burn. If you don’t feel comfortable with the idea of making your own nutrient mix, there are a number of mixes available which are specifically for the cultivation of marijuana. Read more about soil in the article "Marijuana Soil"

Watering in soil

Watering soil grown cannabis

There are no hard and fast rules when it comes to watering a marijuana plant since the requirements of the plant are determined by the environment it's growing in. If the environment is very hot, the plant will use more water. If the plant is receiving the maximum nutrients, it can absorb. Water acts a vehicle for dissolved nutrients and minerals, being absorbed through the roots before spreading through the rest of the plant. It also cools a plant down, fills up cells to keep the plant structurally sound, and is required for photosynthesis.

In general, water enough so that your soil is faintly moist, but not wet. If the soil is too wet, you risk fungal growth and root damage.

Thanks for reading. Please leave comments or questions below and don't forget to download my free grow bible


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Comment Section

29 thoughts on “Indoor Marijuana Growing In Soil

By Ryan on 20 September 2015

I keep a rabbit pen on the side of my house, and was curious about using their droppings in my soil for added nutrients. They have been raised on a diet of Timothy hay, sunflower seeds, pumpkin seeds, carrot, banana, papaya and the occasional fresh watermelon or cantaloupe. Would this be an ok additive?

By latewood on 23 September 2015

Have you done a search on the viability of using Rabbit manure on vegetables? That would be a good place to start.

Another option would be to join the ILGM Support forum and ask the many members; Many of who grow vegetables, organically, and may have some insight to contribute to your query

By ltgrower on 29 December 2015

Rabbit droppings make for excellent soil when starting. Rabbit droppings cannot burn your plants regardless of how much you use. After planting seedlings however I suggest a good nutrient based diet for the growing phase used once and week, then for the flowering phase used 3 times a week.

By Fernando on 5 October 2015


By Flint on 28 February 2016

Thank you for all your help, since you've been sending me advise I've went from someone that wasn't sure that I
wanted to grow but didn't think I could, to someone that is a little more comfortable with what I'm doing.
I am in my fourth grow and I feel very confident that I will soon be at the end of another successful grow.
I want to stop growing from street seeds and start with some real good Strawberry cough, Blueberry kush, and some Black and White widow.
After this harvest, I'll be sending you a money order or cashiers check for the afore mentioned seeds!
Thanks again,

By Jennifer ILGM on 1 March 2016

Hi Flint, Thank you so much for sharing. We are really happy to be of any help. Let us know if you have any questions.

By Flintz on 12 June 2016

I've got two flowered plants and it seems that they have slowed in growing does this happen at the end of the life term of the plant?

By latewood.ILGM on 14 June 2016


Of course plants stop growing at the end of their life cycle. Is this a trick question? LOL 🙂

I suggest you join our support forum in order to expose yourself to many knowledgeable growers and experts willing to help you succeed. 🙂

By emerson on 8 July 2016

Thank you for the lesson .i would like to know the temperature for indoor growing ?

By Darcy Canevari-Hill on 7 November 2016

I'm so confused. I don't even know where to start. First I THINK I downloaded your Bible. I received at least 3 messages from Robert. I see so much information and also see ADS for this Bible to download. I thought I DID that already. I DON'T KNOW.
I have some seeds started indoors .Some are labeled with date planted and strain type also have some notes as to which soils I tried. I see itty bitty BUGS. They don't seem to be eating the plants. Some plants are flowering. I tried trimming just 2 plants ONCE . It seemed to work and spread out a little but I am too scared to try it again. A couple plants just keeled over and died while others are hanging in there. I am also experimenting with different types of containers. I probably should have just followed YOUR step by step instructions but I think it might take me a week just to research your choice vocabulary in said articles. Like I said before I am confused and your emails are long and maybe too informative I Don't know. Maybe I need a marijuana growers FOR DUMMIES.

By Roy ILGM on 8 November 2016

Hi Darcy, I admit there are more than one way to grow our beloved plants. Maybe you could hop onto our support forum. Our experts there are happy to help you as are fellow growers.

By doris Grierson on 10 November 2016

where do you get the light my windows are kind of high and no ledge how much light do they need do you buy special bulbs ?

By Andre Dittrich on 6 March 2017

I usually obtain my super worms by going to

By Laurap on 17 March 2017

Starting out indoors with auto ww.
I've never done either.

By joy on 12 June 2017


By Robert Betancourt on 16 August 2017

Important Info, Thank's

By Mike on 26 August 2017

Going to try my hand at an indoor grow using White Widow Auto. Can I Scrog or use LST to increase yields? Or should I just let it grow on its merry way?

By Keith on 29 September 2017

Thanks, Robert. My first grow wasn't a huge success in quantity (harvested about half of what I should've) but it was quality &what I gained in experience & knowledge will be irreplaceable in keeping my everyday nerve pain in check. Thank you so much for helping me get back some quality of life. You truly are making the world a better place.

By Linda on 5 September 2018

I'm first timer,indoor grower ,started with 4 plants ended with 2 ,both are about 3 is tall with alo t of small white flowers and seeds the other is a beautiful green plant that I love,what can I do with seedy plant.? Is it any good ? I am a Lupus patient .

By latewood_ILGM on 12 September 2018


First let me say I am sorry you have Lupas. I have a close friend afflicted also.

Cull the seedy plant if you are sure the other is a female. If one is flowering and the other is not; You may have a male and a female with seeds. I suggest you buy feminized seeds from here on out to make sure you get you medicine and I also think you should join us at and allow us to help guide you to a successful harvest.

Pollen sacks open and produce little flowers when the pollen is spread. If the plant has seeds on it, the the plant is a female that has been pollinated or a hermaphrodire plant that produces male and female flowers. Without pictures, it is hard to tell what the pretty green without

Hope this helps. We would like to see you grow successfully. 🙂

By latewood_ILGM on 12 September 2018

Sorry...Linda...I am legally lblind 🙂

By Gary Baier on 17 September 2018

Can I use any nutrients thruout my grow even if my babies r in fox farms ocean forest if so at what point should I start

By latewood_ILGM on 24 September 2018

Gary Baier,

A hot soil like FoxFarm will contain the necessary nutrition to get you through the vegetative cycle for the most part. You need to watch your plants in order to make sure they retain a nice green color. In general we recommend that you refrain from adding nutrients in a Foxfarm soil grow until the flowering phase. This is because the FF soil has enough nutrition for 4-8 weeks depending on environment, lamp intensity and how aggressively the genetics are.

Happy growing 🙂

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