How to Choose the Best Soil for Growing Weed Indoors

For people who have done some amount of farming, picking the right kind of soil for whatever plant comes easily. But for newbies trying out their green thumb, this may appear an uphill task. Is soil just soil? What role does soil play in the final outcome of the crop and what you should be looking for when picking the right kind of soil? Before you settle on which soil to buy for your indoor grow, you need to what makes for a good soil for the kind of crop that you are looking to grow.

Cannabis is often regarded as a weed (thus its name) because it pops up and thrives in diverse conditions. However, this does not mean that you should just scatter your seeds in the backyard and hope for the best.

Yes, your marijuana can grow in an array of soils, but to truly flourish and to produce great THC amounts, lots of trichomes, and other beneficial cannabinoids—it needs soil with the right variables.

The variables are:

  • Great water retention – the ability to hold water without getting muddy
  • Proper drainage
  • The right nitrogen to phosphorous ratio
  • Good loose texture
  • The right bacteria to fungus ratio
  • The right soil pH

Factors To Consider When Picking Soil for Indoor Cannabis Growing

Go for Dark, Rich Soil

Sandy soils may be nice to touch and run through your palms, but as you may imagine, they lose water as fast as the sand falls through your fingers. Sandy soil will also hold less moisture and this may result in your plants drying out pretty fast. This also translates to holding fewer nutrients and your plants will be starving in no time. With this, it is better to leave sandy soils for the beaches and opt for dark rich soils such as loamy soils.

Loamy soils on the other hand are able to retain moisture, water and nutrients. The dark color also protects the roots from excessive light and heat, making this soil ideal for an indoor grow.

Touch the Soil if You Can

Do not stop at looking at the soil but go ahead and touch it. The texture should be soft, the temperature moderate and the soil should form a ball when you roll it in your palm. This shows how well the particles come together to retain moisture and nutrients. The best soil is normally fluffy, airy and light.

Making Average Soil Better for Cannabis Growing

You are not doomed if your soil does not meet the optimum requirements since there are a few things you can do to make this better. As long as you have picked the right kind of soil to begin with, you can add the following ingredients to make your indoor soil better.


Should your soil be too condensed and you need to make it lighter and airy you can consider adding perlite to it. Perlites are light airy rocks that add oxygen to the soil and enhance its drainage ability. Depending on your needs, Perlite can be as much as 40% of the total volume. If you are planning to use a lot of nutrients and intend to protect against nutrient burn, use more Perlite.

Coco Coir

Should your soil particles be too spread apart and you are afraid that the soil will not be able to hold water, you can consider adding coco coir.

Coco coir is derived from coconut husks and it improves the water retention capacity of soil without making it heavy. It also decreases the chances of overwatering and enhances root development. When adding to your indoor soil, keep coco coir below 30%.

Worm Casting

As strange as this may sound, adding earth worms to your soil is a possibility. Worms excrete nutrients that are very beneficial to the cannabis plants. They also move through the soil to aerate the soil. Luckily, you can purchase worms or worm poop to add to your soil from most local stores that stock farm nutrients. This will improve your soil’s texture, aeration, retention of moisture, and drainage.

Making Your Own Soil for Cannabis Growing

For newbies, making your own soil can sound a bit strange. But it is a possibility and it may come in handy when you cannot find the right soil.

Pig and cow excrement that has stayed for at least one year is good soil. Actually, it is usually sold as high-quality fertilizer because it contains the nutrients required by cannabis plants. Mix this in a ratio of 50-50 with sand to get amazing yields. Top soil from excavation companies is another great option for indoor soil for weed cultivation.

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