Growing Guides

Best Soil for Cannabis – All The Help You Need In One Place

Liam on February 27, 2017 0 Comments


Growing your own marijuana certainly requires a green thumb – pun intended – but it can be a very rewarding experience for cannabis enthusiasts.

Whether you are looking to create a medicinal home garden, or a major greenhouse operation for recreational sales, choosing the right kind of soil is one of the most important decisions that can affect that quality of your marijuana.

Read on for everything you need to know about growing weed the old fashioned way.

What’s the Best Soil for Growing Weed

In order to grow a healthy cannabis harvest, besides investing in top rated led grow lights, you first need to invest in good quality soil. With so many different types of soil on the market, it is important that you know what to look for on the shelf.

The most important thing when choosing cannabis soil is that it is able to provide your plant with a good balance of three things: nutrition, water, and oxygen.

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To achieve this goal, search for a soil that has the following characteristics:

  • Nutrient-rich
  • Loose texture
  • A balance of drainability and water retention[/thrive_icon_box]

This type of soil should create the perfect environment for your cannabis seeds to grow.


In the wild, the cannabis plant grows very long roots that will extend in order to reach vital nutrient pockets naturally found within the earth.

If you are growing indoors or in grow tent or in flower pot, however, your plant will not have as much space for its roots to extend so it is vitally important that you choose a nutrient rich soil that will allow the plant to prosper in its limited environment.

When choosing soil, you will want to opt for a mixture that is dark and rich (but not heavy), as pale soils often lack important nutrients.

You will also want to stay away from “time release” nutrient soils, as these mixtures release too much nitrogen during the flowering stage for the cannabis plant, and therefore could harm your buds.

Many soils that include “fertilizer” in their ingredients list actually include time-released nutrients, so it is better to steer clear of these mixtures.

For indoor growers, it is especially important that you are aware of the nutrients offered by your soil so that your plant is getting just as much nourishment as if it were grown outdoors.

Having a stable pH value can also support the healthy growth of your plant.

Soil Texture:

In addition to nutrients, getting the right soil texture is crucial to the health of your plant as it will allow the proper amount of oxygen and water to reach its roots.

One of the most common mistakes that first-time growers make, is that they accidentally suffocate their plants by adding compressed, heavy soil to the pot.

To avoid this mistake, you will want to choose a loose soil mixture or create loose texture yourself by combining nutrient-rich soil with vermiculite or perlite.

If you do buy your soil for a garden store, be aware that most large bags automatically come compressed, and you will need to stir up the soil so that it loosens.

Perlite and vermiculite are two commonly used soil additive that are sometimes used interchangeably by marijuana growers to adjust soil texture, though they are slightly different.

Vermiculite is much better at retaining water than perlite, but it is less effective at aerating your roots and draining your soil. If you do choose vermiculite, be careful not to overwater your plants, as this is another common mistake that first-time growers make.

Mixing perlite and vermiculite together can create the perfect texture and ensure that your soil is loose enough to properly drain, but can still retain enough water to hydrate your plant.

Many weed growers opt for this combination but recommend that you keep your total density of perlite and/or vermiculite less than 50% compared to the amount of soil.


Some of the most common ingredients that are cannabis-friendly include coco coir (also known as coco fiber), perlite, composted forest humus, sandy loam, earthworm castings, sphagnum peat moss, dolimite lime, kelp, bat guano, Azomite, pumice, fish meal, leonardite andmycorrhizae.

These ingredients may already be included in your soil mixture, or you can add them yourself for increased nutrition.

Pros and Cons of Soil Growing

When it comes to growing cannabis, there are two main methods: soil growing and using a hydroponic system. Many first time growers opt for soil growing as it is the most organic route and it can produce the same high-quality results without an expensive startup cost.

However, there are many pros and cons to soil growing that you should consider before getting down in the dirt.

Pros Cons
Organic Harder to control the health of your harvest/prevent the spread of disease
Cost effective/minimal startup cost Your harvest is less likely to be affected by insects
Easier irrigation compared to a hydroponic system No need for pesticides
Strong weed stench Hydroponic growing can often produce faster results and larger harvests
Can be done either indoors or outdoors
Different soils can produce different tastes for your cannabis harvest
Time proven method that has been used for centuries with documented results

Both soil growing and hydroponic growing are methods that can produce high-quality results, which method of growing weed is better depends on your personal preference, the amount of weed you are hoping to grow, and your startup budget.

How to Make DIY Homemade Soil

Mixing your own soil gives you the most control over the nutritional balance of your plants – though it takes some knowledge of the three stages of plant growth diet to master the proper nutritional ratios.

Start With the Right Soil Base

To begin, it is important that you choose a nutrient-rich soil base. This soil should not be overly sandy or pale, rather, it should be dark and rich.

Once you have the right soil base (and it has been sterilized, typically with heat), you may need to adjust its texture with a soil additive like perlite or vermiculite so that it is loose and can drain easily, while retaining enough water for hydration.

Combining these soil additives can significantly improve your soil texture, as vermiculite can ensure that your soil has enough water retention, while the white airy “rocks” of perlite can ensure adequate aeration.

Keep in mind, however, that your total amount of perlite and vermiculite should never exceed 50% of your total soil mixture.

Once you choose the right soil base, you will need to consider nutrients next. Your plant’s diet depends on the stage of growth it is currently at.

For example, cannabis seeds require an equal proportion of turf, worm meal, and perlite, whereas plants in the flowering stage require a balance of turf, worm meal, and compost.

Seedling Stage

If you are growing outdoors, it is better not to add too many additional nutrients to your soil during the seedling stage, as you could easily over-fertilize your seeds and stunt their growth.

However, if you know that you are growing your cannabis in an area that naturally has too much compost, you can add chalk to balance it out and achieve the perfect nutrient ratio.

If you are growing indoors, on the other hand, your soil won’t have the same natural reservoir of nutrients found in the Earth so you can add seedling nutrition and root boosters at this stage.

Root boosters support healthy seedling growth by offering essential bacteria, enzymes, and other important compounds.

Seedling nutrients also help support the proper ratio for sprouts. Another option in place of seedling nutrients is to use the same fertilizer you would use during the vegetative stage but at a quarter of the normal dose.

You should also remember that unless your fertilizer is specifically intended for cannabis, it may be too strong and should therefore always be used at a reduced dose.

Growing and Flowering Stage

Once your plants enter the growing stage, the main focus with your homemade soil should be on the NPK balance, or the percentage of nitrogen, phosphorous, and potassium.

A common rule of thumb for the growing stage is to have twice as much nitrogen as phosphorus in your soil, and your potassium level should be anywhere from one-third to one-half of the amount of nitrogen.

As you enter the flowering stage, your NPK balance should significantly change, with a drastic decrease in nitrogen, an increase in phosphorous, and a stable amount of potassium.

You can add specialized fertilizers during this stage for added nutrition, but be careful as you don’t want to add excessive nitrogen so choose wisely and use a reduced dose. You will be able to tell that you are over-fertilizing your plant if its leaves start turning yellow.

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